rocksdb/

db_options.rs

// Copyright 2020 Tyler Neely
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::ffi::CStr;
use std::path::Path;
use std::ptr::{null_mut, NonNull};
use std::slice;
use std::sync::Arc;

use libc::{self, c_char, c_double, c_int, c_uchar, c_uint, c_void, size_t};

use crate::column_family::ColumnFamilyTtl;
use crate::statistics::{Histogram, HistogramData, StatsLevel};
use crate::{
    compaction_filter::{self, CompactionFilterCallback, CompactionFilterFn},
    compaction_filter_factory::{self, CompactionFilterFactory},
    comparator::{
        ComparatorCallback, ComparatorWithTsCallback, CompareFn, CompareTsFn, CompareWithoutTsFn,
    },
    db::DBAccess,
    env::Env,
    ffi,
    ffi_util::{from_cstr, to_cpath, CStrLike},
    merge_operator::{
        self, full_merge_callback, partial_merge_callback, MergeFn, MergeOperatorCallback,
    },
    slice_transform::SliceTransform,
    statistics::Ticker,
    ColumnFamilyDescriptor, Error, SnapshotWithThreadMode,
};

pub(crate) struct WriteBufferManagerWrapper {
    pub(crate) inner: NonNull<ffi::rocksdb_write_buffer_manager_t>,
}

impl Drop for WriteBufferManagerWrapper {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_write_buffer_manager_destroy(self.inner.as_ptr());
        }
    }
}

#[derive(Clone)]
pub struct WriteBufferManager(pub(crate) Arc<WriteBufferManagerWrapper>);

impl WriteBufferManager {
    /// <https://github.com/facebook/rocksdb/wiki/Write-Buffer-Manager>
    /// Write buffer manager helps users control the total memory used by memtables across multiple column families and/or DB instances.
    /// Users can enable this control by 2 ways:
    ///
    /// 1- Limit the total memtable usage across multiple column families and DBs under a threshold.
    /// 2- Cost the memtable memory usage to block cache so that memory of RocksDB can be capped by the single limit.
    /// The usage of a write buffer manager is similar to rate_limiter and sst_file_manager.
    /// Users can create one write buffer manager object and pass it to all the options of column families or DBs whose memtable size they want to be controlled by this object.
    ///
    /// A memory limit is given when creating the write buffer manager object. RocksDB will try to limit the total memory to under this limit.
    ///
    /// a flush will be triggered on one column family of the DB you are inserting to,
    ///
    /// If mutable memtable size exceeds about 90% of the limit,
    /// If the total memory is over the limit, more aggressive flush may also be triggered only if the mutable memtable size also exceeds 50% of the limit.
    /// Both checks are needed because if already more than half memory is being flushed, triggering more flush may not help.
    ///
    /// The total memory is counted as total memory allocated in the arena, even if some of that may not yet be used by memtable.
    ///
    /// buffer_size: the memory limit in bytes.
    /// allow_stall: If set true, it will enable stalling of all writers when memory usage exceeds buffer_size (soft limit).
    ///             It will wait for flush to complete and memory usage to drop down
    pub fn new_write_buffer_manager(buffer_size: size_t, allow_stall: bool) -> Self {
        let inner = NonNull::new(unsafe {
            ffi::rocksdb_write_buffer_manager_create(buffer_size, allow_stall)
        })
        .unwrap();
        WriteBufferManager(Arc::new(WriteBufferManagerWrapper { inner }))
    }

    /// Users can set up RocksDB to cost memory used by memtables to block cache.
    /// This can happen no matter whether you enable memtable memory limit or not.
    /// This option is added to manage memory (memtables + block cache) under a single limit.
    ///
    /// buffer_size: the memory limit in bytes.
    /// allow_stall: If set true, it will enable stalling of all writers when memory usage exceeds buffer_size (soft limit).
    ///             It will wait for flush to complete and memory usage to drop down
    /// cache: the block cache instance
    pub fn new_write_buffer_manager_with_cache(
        buffer_size: size_t,
        allow_stall: bool,
        cache: Cache,
    ) -> Self {
        let inner = NonNull::new(unsafe {
            ffi::rocksdb_write_buffer_manager_create_with_cache(
                buffer_size,
                cache.0.inner.as_ptr(),
                allow_stall,
            )
        })
        .unwrap();
        WriteBufferManager(Arc::new(WriteBufferManagerWrapper { inner }))
    }

    /// Returns the WriteBufferManager memory usage in bytes.
    pub fn get_usage(&self) -> usize {
        unsafe { ffi::rocksdb_write_buffer_manager_memory_usage(self.0.inner.as_ptr()) }
    }

    /// Returns the current buffer size in bytes.
    pub fn get_buffer_size(&self) -> usize {
        unsafe { ffi::rocksdb_write_buffer_manager_buffer_size(self.0.inner.as_ptr()) }
    }

    /// Set the buffer size in bytes.
    pub fn set_buffer_size(&self, new_size: usize) {
        unsafe {
            ffi::rocksdb_write_buffer_manager_set_buffer_size(self.0.inner.as_ptr(), new_size);
        }
    }

    /// Returns if WriteBufferManager is enabled.
    pub fn enabled(&self) -> bool {
        unsafe { ffi::rocksdb_write_buffer_manager_enabled(self.0.inner.as_ptr()) }
    }

    /// set the allow_stall flag.
    pub fn set_allow_stall(&self, allow_stall: bool) {
        unsafe {
            ffi::rocksdb_write_buffer_manager_set_allow_stall(self.0.inner.as_ptr(), allow_stall);
        }
    }
}

pub(crate) struct CacheWrapper {
    pub(crate) inner: NonNull<ffi::rocksdb_cache_t>,
}

impl Drop for CacheWrapper {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_cache_destroy(self.inner.as_ptr());
        }
    }
}

#[derive(Clone)]
pub struct Cache(pub(crate) Arc<CacheWrapper>);

impl Cache {
    /// Creates an LRU cache with capacity in bytes.
    pub fn new_lru_cache(capacity: size_t) -> Cache {
        let inner = NonNull::new(unsafe { ffi::rocksdb_cache_create_lru(capacity) }).unwrap();
        Cache(Arc::new(CacheWrapper { inner }))
    }

    /// Creates an LRU cache with custom options.
    pub fn new_lru_cache_opts(opts: &LruCacheOptions) -> Cache {
        let inner =
            NonNull::new(unsafe { ffi::rocksdb_cache_create_lru_opts(opts.inner) }).unwrap();
        Cache(Arc::new(CacheWrapper { inner }))
    }

    /// Creates a HyperClockCache with capacity in bytes.
    ///
    /// `estimated_entry_charge` is an important tuning parameter. The optimal
    /// choice at any given time is
    /// `(cache.get_usage() - 64 * cache.get_table_address_count()) /
    /// cache.get_occupancy_count()`, or approximately `cache.get_usage() /
    /// cache.get_occupancy_count()`.
    ///
    /// However, the value cannot be changed dynamically, so as the cache
    /// composition changes at runtime, the following tradeoffs apply:
    ///
    /// * If the estimate is substantially too high (e.g., 25% higher),
    ///   the cache may have to evict entries to prevent load factors that
    ///   would dramatically affect lookup times.
    /// * If the estimate is substantially too low (e.g., less than half),
    ///   then meta data space overhead is substantially higher.
    ///
    /// The latter is generally preferable, and picking the larger of
    /// block size and meta data block size is a reasonable choice that
    /// errs towards this side.
    pub fn new_hyper_clock_cache(capacity: size_t, estimated_entry_charge: size_t) -> Cache {
        Cache(Arc::new(CacheWrapper {
            inner: NonNull::new(unsafe {
                ffi::rocksdb_cache_create_hyper_clock(capacity, estimated_entry_charge)
            })
            .unwrap(),
        }))
    }

    /// Returns the cache memory usage in bytes.
    pub fn get_usage(&self) -> usize {
        unsafe { ffi::rocksdb_cache_get_usage(self.0.inner.as_ptr()) }
    }

    /// Returns the pinned memory usage in bytes.
    pub fn get_pinned_usage(&self) -> usize {
        unsafe { ffi::rocksdb_cache_get_pinned_usage(self.0.inner.as_ptr()) }
    }

    /// Sets cache capacity in bytes.
    pub fn set_capacity(&mut self, capacity: size_t) {
        unsafe {
            ffi::rocksdb_cache_set_capacity(self.0.inner.as_ptr(), capacity);
        }
    }
}

#[derive(Default)]
pub(crate) struct OptionsMustOutliveDB {
    env: Option<Env>,
    row_cache: Option<Cache>,
    blob_cache: Option<Cache>,
    block_based: Option<BlockBasedOptionsMustOutliveDB>,
    write_buffer_manager: Option<WriteBufferManager>,
    sst_file_manager: Option<crate::SstFileManager>,
}

impl OptionsMustOutliveDB {
    pub(crate) fn clone(&self) -> Self {
        Self {
            env: self.env.clone(),
            row_cache: self.row_cache.clone(),
            blob_cache: self.blob_cache.clone(),
            block_based: self
                .block_based
                .as_ref()
                .map(BlockBasedOptionsMustOutliveDB::clone),
            write_buffer_manager: self.write_buffer_manager.clone(),
            sst_file_manager: self.sst_file_manager.clone(),
        }
    }
}

#[derive(Default)]
struct BlockBasedOptionsMustOutliveDB {
    block_cache: Option<Cache>,
}

impl BlockBasedOptionsMustOutliveDB {
    fn clone(&self) -> Self {
        Self {
            block_cache: self.block_cache.clone(),
        }
    }
}

/// Database-wide options around performance and behavior.
///
/// Please read the official tuning [guide](https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide)
/// and most importantly, measure performance under realistic workloads with realistic hardware.
///
/// # Examples
///
/// ```
/// use rocksdb::{Options, DB};
/// use rocksdb::DBCompactionStyle;
///
/// fn badly_tuned_for_somebody_elses_disk() -> DB {
///    let path = "path/for/rocksdb/storageX";
///    let mut opts = Options::default();
///    opts.create_if_missing(true);
///    opts.set_max_open_files(10000);
///    opts.set_use_fsync(false);
///    opts.set_bytes_per_sync(8388608);
///    opts.optimize_for_point_lookup(1024);
///    opts.set_table_cache_num_shard_bits(6);
///    opts.set_max_write_buffer_number(32);
///    opts.set_write_buffer_size(536870912);
///    opts.set_target_file_size_base(1073741824);
///    opts.set_min_write_buffer_number_to_merge(4);
///    opts.set_level_zero_stop_writes_trigger(2000);
///    opts.set_level_zero_slowdown_writes_trigger(0);
///    opts.set_compaction_style(DBCompactionStyle::Universal);
///    opts.set_disable_auto_compactions(true);
///
///    DB::open(&opts, path).unwrap()
/// }
/// ```
pub struct Options {
    pub(crate) inner: *mut ffi::rocksdb_options_t,
    pub(crate) outlive: OptionsMustOutliveDB,
}

/// Optionally disable WAL or sync for this write.
///
/// # Examples
///
/// Making an unsafe write of a batch:
///
/// ```
/// use rocksdb::{DB, Options, WriteBatch, WriteOptions};
///
/// let tempdir = tempfile::Builder::new()
///     .prefix("_path_for_rocksdb_storageY1")
///     .tempdir()
///     .expect("Failed to create temporary path for the _path_for_rocksdb_storageY1");
/// let path = tempdir.path();
/// {
///     let db = DB::open_default(path).unwrap();
///     let mut batch = WriteBatch::default();
///     batch.put(b"my key", b"my value");
///     batch.put(b"key2", b"value2");
///     batch.put(b"key3", b"value3");
///
///     let mut write_options = WriteOptions::default();
///     write_options.set_sync(false);
///     write_options.disable_wal(true);
///
///     db.write_opt(batch, &write_options);
/// }
/// let _ = DB::destroy(&Options::default(), path);
/// ```
pub struct WriteOptions {
    pub(crate) inner: *mut ffi::rocksdb_writeoptions_t,
}

pub struct LruCacheOptions {
    pub(crate) inner: *mut ffi::rocksdb_lru_cache_options_t,
}

/// Optionally wait for the memtable flush to be performed.
///
/// # Examples
///
/// Manually flushing the memtable:
///
/// ```
/// use rocksdb::{DB, Options, FlushOptions};
///
/// let tempdir = tempfile::Builder::new()
///     .prefix("_path_for_rocksdb_storageY2")
///     .tempdir()
///     .expect("Failed to create temporary path for the _path_for_rocksdb_storageY2");
/// let path = tempdir.path();
/// {
///     let db = DB::open_default(path).unwrap();
///
///     let mut flush_options = FlushOptions::default();
///     flush_options.set_wait(true);
///
///     db.flush_opt(&flush_options);
/// }
/// let _ = DB::destroy(&Options::default(), path);
/// ```
pub struct FlushOptions {
    pub(crate) inner: *mut ffi::rocksdb_flushoptions_t,
}

/// For configuring block-based file storage.
pub struct BlockBasedOptions {
    pub(crate) inner: *mut ffi::rocksdb_block_based_table_options_t,
    outlive: BlockBasedOptionsMustOutliveDB,
}

pub struct ReadOptions {
    pub(crate) inner: *mut ffi::rocksdb_readoptions_t,
    // The `ReadOptions` owns a copy of the timestamp and iteration bounds.
    // This is necessary to ensure the pointers we pass over the FFI live as
    // long as the `ReadOptions`. This way, when performing the read operation,
    // the pointers are guaranteed to be valid.
    timestamp: Option<Vec<u8>>,
    iter_start_ts: Option<Vec<u8>>,
    iterate_upper_bound: Option<Vec<u8>>,
    iterate_lower_bound: Option<Vec<u8>>,
}

/// Configuration of cuckoo-based storage.
pub struct CuckooTableOptions {
    pub(crate) inner: *mut ffi::rocksdb_cuckoo_table_options_t,
}

/// For configuring external files ingestion.
///
/// # Examples
///
/// Move files instead of copying them:
///
/// ```
/// use rocksdb::{DB, IngestExternalFileOptions, SstFileWriter, Options};
///
/// let writer_opts = Options::default();
/// let mut writer = SstFileWriter::create(&writer_opts);
/// let tempdir = tempfile::Builder::new()
///     .tempdir()
///     .expect("Failed to create temporary folder for the _path_for_sst_file");
/// let path1 = tempdir.path().join("_path_for_sst_file");
/// writer.open(path1.clone()).unwrap();
/// writer.put(b"k1", b"v1").unwrap();
/// writer.finish().unwrap();
///
/// let tempdir2 = tempfile::Builder::new()
///     .prefix("_path_for_rocksdb_storageY3")
///     .tempdir()
///     .expect("Failed to create temporary path for the _path_for_rocksdb_storageY3");
/// let path2 = tempdir2.path();
/// {
///   let db = DB::open_default(&path2).unwrap();
///   let mut ingest_opts = IngestExternalFileOptions::default();
///   ingest_opts.set_move_files(true);
///   db.ingest_external_file_opts(&ingest_opts, vec![path1]).unwrap();
/// }
/// let _ = DB::destroy(&Options::default(), path2);
/// ```
pub struct IngestExternalFileOptions {
    pub(crate) inner: *mut ffi::rocksdb_ingestexternalfileoptions_t,
}

// Safety note: auto-implementing Send on most db-related types is prevented by the inner FFI
// pointer. In most cases, however, this pointer is Send-safe because it is never aliased and
// rocksdb internally does not rely on thread-local information for its user-exposed types.
unsafe impl Send for Options {}
unsafe impl Send for WriteOptions {}
unsafe impl Send for LruCacheOptions {}
unsafe impl Send for FlushOptions {}
unsafe impl Send for BlockBasedOptions {}
unsafe impl Send for CuckooTableOptions {}
unsafe impl Send for ReadOptions {}
unsafe impl Send for IngestExternalFileOptions {}
unsafe impl Send for CacheWrapper {}
unsafe impl Send for CompactOptions {}
unsafe impl Send for WriteBufferManagerWrapper {}

// Sync is similarly safe for many types because they do not expose interior mutability, and their
// use within the rocksdb library is generally behind a const reference
unsafe impl Sync for Options {}
unsafe impl Sync for WriteOptions {}
unsafe impl Sync for LruCacheOptions {}
unsafe impl Sync for FlushOptions {}
unsafe impl Sync for BlockBasedOptions {}
unsafe impl Sync for CuckooTableOptions {}
unsafe impl Sync for ReadOptions {}
unsafe impl Sync for IngestExternalFileOptions {}
unsafe impl Sync for CacheWrapper {}
unsafe impl Sync for CompactOptions {}
unsafe impl Sync for WriteBufferManagerWrapper {}

impl Drop for Options {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_options_destroy(self.inner);
        }
    }
}

impl Clone for Options {
    fn clone(&self) -> Self {
        let inner = unsafe { ffi::rocksdb_options_create_copy(self.inner) };
        assert!(!inner.is_null(), "Could not copy RocksDB options");

        Self {
            inner,
            outlive: self.outlive.clone(),
        }
    }
}

impl Drop for BlockBasedOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_block_based_options_destroy(self.inner);
        }
    }
}

impl Drop for CuckooTableOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_cuckoo_options_destroy(self.inner);
        }
    }
}

impl Drop for FlushOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_flushoptions_destroy(self.inner);
        }
    }
}

impl Drop for WriteOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_writeoptions_destroy(self.inner);
        }
    }
}

impl Drop for LruCacheOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_lru_cache_options_destroy(self.inner);
        }
    }
}

impl Drop for ReadOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_readoptions_destroy(self.inner);
        }
    }
}

impl Drop for IngestExternalFileOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_destroy(self.inner);
        }
    }
}

impl BlockBasedOptions {
    /// Approximate size of user data packed per block. Note that the
    /// block size specified here corresponds to uncompressed data. The
    /// actual size of the unit read from disk may be smaller if
    /// compression is enabled. This parameter can be changed dynamically.
    pub fn set_block_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_block_based_options_set_block_size(self.inner, size);
        }
    }

    /// Block size for partitioned metadata. Currently applied to indexes when
    /// kTwoLevelIndexSearch is used and to filters when partition_filters is used.
    /// Note: Since in the current implementation the filters and index partitions
    /// are aligned, an index/filter block is created when either index or filter
    /// block size reaches the specified limit.
    ///
    /// Note: this limit is currently applied to only index blocks; a filter
    /// partition is cut right after an index block is cut.
    pub fn set_metadata_block_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_block_based_options_set_metadata_block_size(self.inner, size as u64);
        }
    }

    /// Note: currently this option requires kTwoLevelIndexSearch to be set as
    /// well.
    ///
    /// Use partitioned full filters for each SST file. This option is
    /// incompatible with block-based filters.
    pub fn set_partition_filters(&mut self, size: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_partition_filters(self.inner, c_uchar::from(size));
        }
    }

    /// Sets global cache for blocks (user data is stored in a set of blocks, and
    /// a block is the unit of reading from disk).
    ///
    /// If set, use the specified cache for blocks.
    /// By default, rocksdb will automatically create and use an 8MB internal cache.
    pub fn set_block_cache(&mut self, cache: &Cache) {
        unsafe {
            ffi::rocksdb_block_based_options_set_block_cache(self.inner, cache.0.inner.as_ptr());
        }
        self.outlive.block_cache = Some(cache.clone());
    }

    /// Disable block cache
    pub fn disable_cache(&mut self) {
        unsafe {
            ffi::rocksdb_block_based_options_set_no_block_cache(self.inner, c_uchar::from(true));
        }
    }

    /// Sets a [Bloom filter](https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter)
    /// policy to reduce disk reads.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::BlockBasedOptions;
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_bloom_filter(10.0, true);
    /// ```
    pub fn set_bloom_filter(&mut self, bits_per_key: c_double, block_based: bool) {
        unsafe {
            let bloom = if block_based {
                ffi::rocksdb_filterpolicy_create_bloom(bits_per_key as _)
            } else {
                ffi::rocksdb_filterpolicy_create_bloom_full(bits_per_key as _)
            };

            ffi::rocksdb_block_based_options_set_filter_policy(self.inner, bloom);
        }
    }

    /// Sets a [Ribbon filter](http://rocksdb.org/blog/2021/12/29/ribbon-filter.html)
    /// policy to reduce disk reads.
    ///
    /// Ribbon filters use less memory in exchange for slightly more CPU usage
    /// compared to an equivalent bloom filter.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::BlockBasedOptions;
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_ribbon_filter(10.0);
    /// ```
    pub fn set_ribbon_filter(&mut self, bloom_equivalent_bits_per_key: c_double) {
        unsafe {
            let ribbon = ffi::rocksdb_filterpolicy_create_ribbon(bloom_equivalent_bits_per_key);
            ffi::rocksdb_block_based_options_set_filter_policy(self.inner, ribbon);
        }
    }

    /// Sets a hybrid [Ribbon filter](http://rocksdb.org/blog/2021/12/29/ribbon-filter.html)
    /// policy to reduce disk reads.
    ///
    /// Uses Bloom filters before the given level, and Ribbon filters for all
    /// other levels. This combines the memory savings from Ribbon filters
    /// with the lower CPU usage of Bloom filters.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::BlockBasedOptions;
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_hybrid_ribbon_filter(10.0, 2);
    /// ```
    pub fn set_hybrid_ribbon_filter(
        &mut self,
        bloom_equivalent_bits_per_key: c_double,
        bloom_before_level: c_int,
    ) {
        unsafe {
            let ribbon = ffi::rocksdb_filterpolicy_create_ribbon_hybrid(
                bloom_equivalent_bits_per_key,
                bloom_before_level,
            );
            ffi::rocksdb_block_based_options_set_filter_policy(self.inner, ribbon);
        }
    }

    /// If cache_index_and_filter_blocks is enabled, cache index and filter blocks with high priority.
    /// If set to true, depending on implementation of block cache,
    /// index and filter blocks may be less likely to be evicted than data blocks.
    pub fn set_cache_index_and_filter_blocks(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_cache_index_and_filter_blocks(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// Defines the index type to be used for SS-table lookups.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{BlockBasedOptions, BlockBasedIndexType, Options};
    ///
    /// let mut opts = Options::default();
    /// let mut block_opts = BlockBasedOptions::default();
    /// block_opts.set_index_type(BlockBasedIndexType::HashSearch);
    /// ```
    pub fn set_index_type(&mut self, index_type: BlockBasedIndexType) {
        let index = index_type as i32;
        unsafe {
            ffi::rocksdb_block_based_options_set_index_type(self.inner, index);
        }
    }

    /// If cache_index_and_filter_blocks is true and the below is true, then
    /// filter and index blocks are stored in the cache, but a reference is
    /// held in the "table reader" object so the blocks are pinned and only
    /// evicted from cache when the table reader is freed.
    ///
    /// Default: false.
    pub fn set_pin_l0_filter_and_index_blocks_in_cache(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_pin_l0_filter_and_index_blocks_in_cache(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// If cache_index_and_filter_blocks is true and the below is true, then
    /// the top-level index of partitioned filter and index blocks are stored in
    /// the cache, but a reference is held in the "table reader" object so the
    /// blocks are pinned and only evicted from cache when the table reader is
    /// freed. This is not limited to l0 in LSM tree.
    ///
    /// Default: false.
    pub fn set_pin_top_level_index_and_filter(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_pin_top_level_index_and_filter(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// Format version, reserved for backward compatibility.
    ///
    /// See full [list](https://github.com/facebook/rocksdb/blob/v8.6.7/include/rocksdb/table.h#L493-L521)
    /// of the supported versions.
    ///
    /// Default: 5.
    pub fn set_format_version(&mut self, version: i32) {
        unsafe {
            ffi::rocksdb_block_based_options_set_format_version(self.inner, version);
        }
    }

    /// Number of keys between restart points for delta encoding of keys.
    /// This parameter can be changed dynamically. Most clients should
    /// leave this parameter alone. The minimum value allowed is 1. Any smaller
    /// value will be silently overwritten with 1.
    ///
    /// Default: 16.
    pub fn set_block_restart_interval(&mut self, interval: i32) {
        unsafe {
            ffi::rocksdb_block_based_options_set_block_restart_interval(self.inner, interval);
        }
    }

    /// Same as block_restart_interval but used for the index block.
    /// If you don't plan to run RocksDB before version 5.16 and you are
    /// using `index_block_restart_interval` > 1, you should
    /// probably set the `format_version` to >= 4 as it would reduce the index size.
    ///
    /// Default: 1.
    pub fn set_index_block_restart_interval(&mut self, interval: i32) {
        unsafe {
            ffi::rocksdb_block_based_options_set_index_block_restart_interval(self.inner, interval);
        }
    }

    /// Set the data block index type for point lookups:
    ///  `DataBlockIndexType::BinarySearch` to use binary search within the data block.
    ///  `DataBlockIndexType::BinaryAndHash` to use the data block hash index in combination with
    ///  the normal binary search.
    ///
    /// The hash table utilization ratio is adjustable using [`set_data_block_hash_ratio`](#method.set_data_block_hash_ratio), which is
    /// valid only when using `DataBlockIndexType::BinaryAndHash`.
    ///
    /// Default: `BinarySearch`
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{BlockBasedOptions, DataBlockIndexType, Options};
    ///
    /// let mut opts = Options::default();
    /// let mut block_opts = BlockBasedOptions::default();
    /// block_opts.set_data_block_index_type(DataBlockIndexType::BinaryAndHash);
    /// block_opts.set_data_block_hash_ratio(0.85);
    /// ```
    pub fn set_data_block_index_type(&mut self, index_type: DataBlockIndexType) {
        let index_t = index_type as i32;
        unsafe {
            ffi::rocksdb_block_based_options_set_data_block_index_type(self.inner, index_t);
        }
    }

    /// Set the data block hash index utilization ratio.
    ///
    /// The smaller the utilization ratio, the less hash collisions happen, and so reduce the risk for a
    /// point lookup to fall back to binary search due to the collisions. A small ratio means faster
    /// lookup at the price of more space overhead.
    ///
    /// Default: 0.75
    pub fn set_data_block_hash_ratio(&mut self, ratio: f64) {
        unsafe {
            ffi::rocksdb_block_based_options_set_data_block_hash_ratio(self.inner, ratio);
        }
    }

    /// If false, place only prefixes in the filter, not whole keys.
    ///
    /// Defaults to true.
    pub fn set_whole_key_filtering(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_whole_key_filtering(self.inner, c_uchar::from(v));
        }
    }

    /// Use the specified checksum type.
    /// Newly created table files will be protected with this checksum type.
    /// Old table files will still be readable, even though they have different checksum type.
    pub fn set_checksum_type(&mut self, checksum_type: ChecksumType) {
        unsafe {
            ffi::rocksdb_block_based_options_set_checksum(self.inner, checksum_type as c_char);
        }
    }

    /// If true, generate Bloom/Ribbon filters that minimize memory internal
    /// fragmentation.
    /// See official [wiki](
    /// https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter#reducing-internal-fragmentation)
    /// for more information.
    ///
    /// Defaults to false.
    /// # Examples
    ///
    /// ```
    /// use rocksdb::BlockBasedOptions;
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_bloom_filter(10.0, true);
    /// opts.set_optimize_filters_for_memory(true);
    /// ```
    pub fn set_optimize_filters_for_memory(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_block_based_options_set_optimize_filters_for_memory(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// Set the top-level index pinning tier.
    ///
    /// Controls when top-level index blocks are pinned in block cache memory.
    /// This affects memory usage and lookup performance for large databases with
    /// multiple levels.
    ///
    /// Default: `BlockBasedTablePinningTier::Fallback`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{BlockBasedOptions, BlockBasedTablePinningTier};
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_top_level_index_pinning_tier(BlockBasedTablePinningTier::FlushAndSimilar);
    /// ```
    pub fn set_top_level_index_pinning_tier(&mut self, pinning_tier: BlockBasedTablePinningTier) {
        unsafe {
            ffi::rocksdb_block_based_options_set_top_level_index_pinning_tier(
                self.inner,
                pinning_tier as c_int,
            );
        }
    }

    /// Set the partition pinning tier.
    ///
    /// Controls when partition blocks (used in partitioned indexes and filters)
    /// are pinned in block cache memory. This affects performance for databases
    /// using partitioned metadata.
    ///
    /// Default: `BlockBasedTablePinningTier::Fallback`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{BlockBasedOptions, BlockBasedTablePinningTier};
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_partition_pinning_tier(BlockBasedTablePinningTier::All);
    /// ```
    pub fn set_partition_pinning_tier(&mut self, pinning_tier: BlockBasedTablePinningTier) {
        unsafe {
            ffi::rocksdb_block_based_options_set_partition_pinning_tier(
                self.inner,
                pinning_tier as c_int,
            );
        }
    }

    /// Set the unpartitioned pinning tier.
    ///
    /// Controls when unpartitioned metadata blocks (index and filter blocks that
    /// are not partitioned) are pinned in block cache memory.
    ///
    /// Default: `BlockBasedTablePinningTier::Fallback`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{BlockBasedOptions, BlockBasedTablePinningTier};
    ///
    /// let mut opts = BlockBasedOptions::default();
    /// opts.set_unpartitioned_pinning_tier(BlockBasedTablePinningTier::None);
    /// ```
    pub fn set_unpartitioned_pinning_tier(&mut self, pinning_tier: BlockBasedTablePinningTier) {
        unsafe {
            ffi::rocksdb_block_based_options_set_unpartitioned_pinning_tier(
                self.inner,
                pinning_tier as c_int,
            );
        }
    }
}

impl Default for BlockBasedOptions {
    fn default() -> Self {
        let block_opts = unsafe { ffi::rocksdb_block_based_options_create() };
        assert!(
            !block_opts.is_null(),
            "Could not create RocksDB block based options"
        );

        Self {
            inner: block_opts,
            outlive: BlockBasedOptionsMustOutliveDB::default(),
        }
    }
}

impl CuckooTableOptions {
    /// Determines the utilization of hash tables. Smaller values
    /// result in larger hash tables with fewer collisions.
    /// Default: 0.9
    pub fn set_hash_ratio(&mut self, ratio: f64) {
        unsafe {
            ffi::rocksdb_cuckoo_options_set_hash_ratio(self.inner, ratio);
        }
    }

    /// A property used by builder to determine the depth to go to
    /// to search for a path to displace elements in case of
    /// collision. See Builder.MakeSpaceForKey method. Higher
    /// values result in more efficient hash tables with fewer
    /// lookups but take more time to build.
    /// Default: 100
    pub fn set_max_search_depth(&mut self, depth: u32) {
        unsafe {
            ffi::rocksdb_cuckoo_options_set_max_search_depth(self.inner, depth);
        }
    }

    /// In case of collision while inserting, the builder
    /// attempts to insert in the next cuckoo_block_size
    /// locations before skipping over to the next Cuckoo hash
    /// function. This makes lookups more cache friendly in case
    /// of collisions.
    /// Default: 5
    pub fn set_cuckoo_block_size(&mut self, size: u32) {
        unsafe {
            ffi::rocksdb_cuckoo_options_set_cuckoo_block_size(self.inner, size);
        }
    }

    /// If this option is enabled, user key is treated as uint64_t and its value
    /// is used as hash value directly. This option changes builder's behavior.
    /// Reader ignore this option and behave according to what specified in
    /// table property.
    /// Default: false
    pub fn set_identity_as_first_hash(&mut self, flag: bool) {
        unsafe {
            ffi::rocksdb_cuckoo_options_set_identity_as_first_hash(self.inner, c_uchar::from(flag));
        }
    }

    /// If this option is set to true, module is used during hash calculation.
    /// This often yields better space efficiency at the cost of performance.
    /// If this option is set to false, # of entries in table is constrained to
    /// be power of two, and bit and is used to calculate hash, which is faster in general.
    /// Default: true
    pub fn set_use_module_hash(&mut self, flag: bool) {
        unsafe {
            ffi::rocksdb_cuckoo_options_set_use_module_hash(self.inner, c_uchar::from(flag));
        }
    }
}

impl Default for CuckooTableOptions {
    fn default() -> Self {
        let opts = unsafe { ffi::rocksdb_cuckoo_options_create() };
        assert!(!opts.is_null(), "Could not create RocksDB cuckoo options");

        Self { inner: opts }
    }
}

// Verbosity of the LOG.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[repr(i32)]
pub enum LogLevel {
    Debug = 0,
    Info,
    Warn,
    Error,
    Fatal,
    Header,
}

impl Options {
    /// Constructs the DBOptions and ColumnFamilyDescriptors by loading the
    /// latest RocksDB options file stored in the specified rocksdb database.
    ///
    /// *IMPORTANT*:
    /// ROCKSDB DOES NOT STORE cf ttl in the options file. If you have set it via
    /// [`ColumnFamilyDescriptor::new_with_ttl`] then you need to set it again after loading the options file.
    /// Tll will be set to [`ColumnFamilyTtl::Disabled`] for all column families for your safety.
    pub fn load_latest<P: AsRef<Path>>(
        path: P,
        env: Env,
        ignore_unknown_options: bool,
        cache: Cache,
    ) -> Result<(Options, Vec<ColumnFamilyDescriptor>), Error> {
        let path = to_cpath(path)?;
        let mut db_options: *mut ffi::rocksdb_options_t = null_mut();
        let mut num_column_families: usize = 0;
        let mut column_family_names: *mut *mut c_char = null_mut();
        let mut column_family_options: *mut *mut ffi::rocksdb_options_t = null_mut();
        unsafe {
            ffi_try!(ffi::rocksdb_load_latest_options(
                path.as_ptr(),
                env.0.inner,
                ignore_unknown_options,
                cache.0.inner.as_ptr(),
                &mut db_options,
                &mut num_column_families,
                &mut column_family_names,
                &mut column_family_options,
            ));
        }
        let options = Options {
            inner: db_options,
            outlive: OptionsMustOutliveDB::default(),
        };
        let column_families = unsafe {
            Options::read_column_descriptors(
                num_column_families,
                column_family_names,
                column_family_options,
            )
        };
        Ok((options, column_families))
    }

    /// read column descriptors from c pointers
    #[inline]
    unsafe fn read_column_descriptors(
        num_column_families: usize,
        column_family_names: *mut *mut c_char,
        column_family_options: *mut *mut ffi::rocksdb_options_t,
    ) -> Vec<ColumnFamilyDescriptor> {
        let column_family_names_iter = unsafe {
            slice::from_raw_parts(column_family_names, num_column_families)
                .iter()
                .map(|ptr| from_cstr(*ptr))
        };
        let column_family_options_iter = unsafe {
            slice::from_raw_parts(column_family_options, num_column_families)
                .iter()
                .map(|ptr| Options {
                    inner: *ptr,
                    outlive: OptionsMustOutliveDB::default(),
                })
        };
        let column_descriptors = column_family_names_iter
            .zip(column_family_options_iter)
            .map(|(name, options)| ColumnFamilyDescriptor {
                name,
                options,
                ttl: ColumnFamilyTtl::Disabled,
            })
            .collect::<Vec<_>>();

        // free pointers
        unsafe {
            slice::from_raw_parts(column_family_names, num_column_families)
                .iter()
                .for_each(|ptr| ffi::rocksdb_free(*ptr as *mut c_void));
            ffi::rocksdb_free(column_family_names as *mut c_void);
            ffi::rocksdb_free(column_family_options as *mut c_void);
        };

        column_descriptors
    }

    /// By default, RocksDB uses only one background thread for flush and
    /// compaction. Calling this function will set it up such that total of
    /// `total_threads` is used. Good value for `total_threads` is the number of
    /// cores. You almost definitely want to call this function if your system is
    /// bottlenecked by RocksDB.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.increase_parallelism(3);
    /// ```
    pub fn increase_parallelism(&mut self, parallelism: i32) {
        unsafe {
            ffi::rocksdb_options_increase_parallelism(self.inner, parallelism);
        }
    }

    /// Optimize level style compaction.
    ///
    /// Default values for some parameters in `Options` are not optimized for heavy
    /// workloads and big datasets, which means you might observe write stalls under
    /// some conditions.
    ///
    /// This can be used as one of the starting points for tuning RocksDB options in
    /// such cases.
    ///
    /// Internally, it sets `write_buffer_size`, `min_write_buffer_number_to_merge`,
    /// `max_write_buffer_number`, `level0_file_num_compaction_trigger`,
    /// `target_file_size_base`, `max_bytes_for_level_base`, so it can override if those
    /// parameters were set before.
    ///
    /// It sets buffer sizes so that memory consumption would be constrained by
    /// `memtable_memory_budget`.
    pub fn optimize_level_style_compaction(&mut self, memtable_memory_budget: usize) {
        unsafe {
            ffi::rocksdb_options_optimize_level_style_compaction(
                self.inner,
                memtable_memory_budget as u64,
            );
        }
    }

    /// Optimize universal style compaction.
    ///
    /// Default values for some parameters in `Options` are not optimized for heavy
    /// workloads and big datasets, which means you might observe write stalls under
    /// some conditions.
    ///
    /// This can be used as one of the starting points for tuning RocksDB options in
    /// such cases.
    ///
    /// Internally, it sets `write_buffer_size`, `min_write_buffer_number_to_merge`,
    /// `max_write_buffer_number`, `level0_file_num_compaction_trigger`,
    /// `target_file_size_base`, `max_bytes_for_level_base`, so it can override if those
    /// parameters were set before.
    ///
    /// It sets buffer sizes so that memory consumption would be constrained by
    /// `memtable_memory_budget`.
    pub fn optimize_universal_style_compaction(&mut self, memtable_memory_budget: usize) {
        unsafe {
            ffi::rocksdb_options_optimize_universal_style_compaction(
                self.inner,
                memtable_memory_budget as u64,
            );
        }
    }

    /// If true, the database will be created if it is missing.
    ///
    /// Default: `false`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.create_if_missing(true);
    /// ```
    pub fn create_if_missing(&mut self, create_if_missing: bool) {
        unsafe {
            ffi::rocksdb_options_set_create_if_missing(
                self.inner,
                c_uchar::from(create_if_missing),
            );
        }
    }

    /// If true, any column families that didn't exist when opening the database
    /// will be created.
    ///
    /// Default: `false`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.create_missing_column_families(true);
    /// ```
    pub fn create_missing_column_families(&mut self, create_missing_cfs: bool) {
        unsafe {
            ffi::rocksdb_options_set_create_missing_column_families(
                self.inner,
                c_uchar::from(create_missing_cfs),
            );
        }
    }

    /// Specifies whether an error should be raised if the database already exists.
    ///
    /// Default: false
    pub fn set_error_if_exists(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_error_if_exists(self.inner, c_uchar::from(enabled));
        }
    }

    /// Enable/disable paranoid checks.
    ///
    /// If true, the implementation will do aggressive checking of the
    /// data it is processing and will stop early if it detects any
    /// errors. This may have unforeseen ramifications: for example, a
    /// corruption of one DB entry may cause a large number of entries to
    /// become unreadable or for the entire DB to become unopenable.
    /// If any of the  writes to the database fails (Put, Delete, Merge, Write),
    /// the database will switch to read-only mode and fail all other
    /// Write operations.
    ///
    /// Default: false
    pub fn set_paranoid_checks(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_paranoid_checks(self.inner, c_uchar::from(enabled));
        }
    }

    /// A list of paths where SST files can be put into, with its target size.
    /// Newer data is placed into paths specified earlier in the vector while
    /// older data gradually moves to paths specified later in the vector.
    ///
    /// For example, you have a flash device with 10GB allocated for the DB,
    /// as well as a hard drive of 2TB, you should config it to be:
    ///   [{"/flash_path", 10GB}, {"/hard_drive", 2TB}]
    ///
    /// The system will try to guarantee data under each path is close to but
    /// not larger than the target size. But current and future file sizes used
    /// by determining where to place a file are based on best-effort estimation,
    /// which means there is a chance that the actual size under the directory
    /// is slightly more than target size under some workloads. User should give
    /// some buffer room for those cases.
    ///
    /// If none of the paths has sufficient room to place a file, the file will
    /// be placed to the last path anyway, despite to the target size.
    ///
    /// Placing newer data to earlier paths is also best-efforts. User should
    /// expect user files to be placed in higher levels in some extreme cases.
    ///
    /// If left empty, only one path will be used, which is `path` passed when
    /// opening the DB.
    ///
    /// Default: empty
    pub fn set_db_paths(&mut self, paths: &[DBPath]) {
        let mut paths: Vec<_> = paths.iter().map(|path| path.inner.cast_const()).collect();
        let num_paths = paths.len();
        unsafe {
            ffi::rocksdb_options_set_db_paths(self.inner, paths.as_mut_ptr(), num_paths);
        }
    }

    /// Use the specified object to interact with the environment,
    /// e.g. to read/write files, schedule background work, etc. In the near
    /// future, support for doing storage operations such as read/write files
    /// through env will be deprecated in favor of file_system.
    ///
    /// Default: Env::default()
    pub fn set_env(&mut self, env: &Env) {
        unsafe {
            ffi::rocksdb_options_set_env(self.inner, env.0.inner);
        }
        self.outlive.env = Some(env.clone());
    }

    /// Sets the SstFileManager to use for tracking SST files and controlling
    /// their deletion rate.
    ///
    /// The SstFileManager can be used to:
    /// * Limit the total size of SST files
    /// * Control the deletion rate of obsolete files
    /// * Track the total size of SST files and trash files
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Env, Options, SstFileManager};
    ///
    /// let env = Env::new().unwrap();
    /// let mut sst_file_manager = SstFileManager::new(&env).unwrap();
    ///
    /// // Set a maximum space limit of 10GB
    /// sst_file_manager.set_max_allowed_space_usage(10 * 1024 * 1024 * 1024);
    ///
    /// // Limit deletion rate to 64MB/s
    /// sst_file_manager.set_delete_rate_bytes_per_second(64 * 1024 * 1024);
    ///
    /// let mut opts = Options::default();
    /// opts.set_sst_file_manager(&sst_file_manager);
    /// ```
    pub fn set_sst_file_manager(&mut self, sst_file_manager: &crate::SstFileManager) {
        unsafe {
            ffi::rocksdb_options_set_sst_file_manager(self.inner, sst_file_manager.0.inner);
        }
        self.outlive.sst_file_manager = Some(sst_file_manager.clone());
    }

    /// Sets the compression algorithm that will be used for compressing blocks.
    ///
    /// Default: `DBCompressionType::Snappy` (`DBCompressionType::None` if
    /// snappy feature is not enabled).
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compression_type(DBCompressionType::Snappy);
    /// ```
    pub fn set_compression_type(&mut self, t: DBCompressionType) {
        unsafe {
            ffi::rocksdb_options_set_compression(self.inner, t as c_int);
        }
    }

    /// Number of threads for parallel compression.
    /// Parallel compression is enabled only if threads > 1.
    /// THE FEATURE IS STILL EXPERIMENTAL
    ///
    /// See [code](https://github.com/facebook/rocksdb/blob/v8.6.7/include/rocksdb/advanced_options.h#L116-L127)
    /// for more information.
    ///
    /// Default: 1
    ///
    /// Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compression_type(DBCompressionType::Zstd);
    /// opts.set_compression_options_parallel_threads(3);
    /// ```
    pub fn set_compression_options_parallel_threads(&mut self, num: i32) {
        unsafe {
            ffi::rocksdb_options_set_compression_options_parallel_threads(self.inner, num);
        }
    }

    /// Sets the compression algorithm that will be used for compressing WAL.
    ///
    /// At present, only ZSTD compression is supported!
    ///
    /// Default: `DBCompressionType::None`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_wal_compression_type(DBCompressionType::Zstd);
    /// // Or None to disable it
    /// opts.set_wal_compression_type(DBCompressionType::None);
    /// ```
    pub fn set_wal_compression_type(&mut self, t: DBCompressionType) {
        match t {
            DBCompressionType::None | DBCompressionType::Zstd => unsafe {
                ffi::rocksdb_options_set_wal_compression(self.inner, t as c_int);
            },
            other => unimplemented!("{:?} is not supported for WAL compression", other),
        }
    }

    /// Sets the bottom-most compression algorithm that will be used for
    /// compressing blocks at the bottom-most level.
    ///
    /// Note that to actually enable bottom-most compression configuration after
    /// setting the compression type, it needs to be enabled by calling
    /// [`set_bottommost_compression_options`](#method.set_bottommost_compression_options) or
    /// [`set_bottommost_zstd_max_train_bytes`](#method.set_bottommost_zstd_max_train_bytes) method with `enabled` argument
    /// set to `true`.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_bottommost_compression_type(DBCompressionType::Zstd);
    /// opts.set_bottommost_zstd_max_train_bytes(0, true);
    /// ```
    pub fn set_bottommost_compression_type(&mut self, t: DBCompressionType) {
        unsafe {
            ffi::rocksdb_options_set_bottommost_compression(self.inner, t as c_int);
        }
    }

    /// Different levels can have different compression policies. There
    /// are cases where most lower levels would like to use quick compression
    /// algorithms while the higher levels (which have more data) use
    /// compression algorithms that have better compression but could
    /// be slower. This array, if non-empty, should have an entry for
    /// each level of the database; these override the value specified in
    /// the previous field 'compression'.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compression_per_level(&[
    ///     DBCompressionType::None,
    ///     DBCompressionType::None,
    ///     DBCompressionType::Snappy,
    ///     DBCompressionType::Snappy,
    ///     DBCompressionType::Snappy
    /// ]);
    /// ```
    pub fn set_compression_per_level(&mut self, level_types: &[DBCompressionType]) {
        unsafe {
            let mut level_types: Vec<_> = level_types.iter().map(|&t| t as c_int).collect();
            ffi::rocksdb_options_set_compression_per_level(
                self.inner,
                level_types.as_mut_ptr(),
                level_types.len() as size_t,
            );
        }
    }

    /// Maximum size of dictionaries used to prime the compression library.
    /// Enabling dictionary can improve compression ratios when there are
    /// repetitions across data blocks.
    ///
    /// The dictionary is created by sampling the SST file data. If
    /// `zstd_max_train_bytes` is nonzero, the samples are passed through zstd's
    /// dictionary generator. Otherwise, the random samples are used directly as
    /// the dictionary.
    ///
    /// When compression dictionary is disabled, we compress and write each block
    /// before buffering data for the next one. When compression dictionary is
    /// enabled, we buffer all SST file data in-memory so we can sample it, as data
    /// can only be compressed and written after the dictionary has been finalized.
    /// So users of this feature may see increased memory usage.
    ///
    /// Default: `0`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_compression_options(4, 5, 6, 7);
    /// ```
    pub fn set_compression_options(
        &mut self,
        w_bits: c_int,
        level: c_int,
        strategy: c_int,
        max_dict_bytes: c_int,
    ) {
        unsafe {
            ffi::rocksdb_options_set_compression_options(
                self.inner,
                w_bits,
                level,
                strategy,
                max_dict_bytes,
            );
        }
    }

    /// Sets compression options for blocks at the bottom-most level.  Meaning
    /// of all settings is the same as in [`set_compression_options`](#method.set_compression_options) method but
    /// affect only the bottom-most compression which is set using
    /// [`set_bottommost_compression_type`](#method.set_bottommost_compression_type) method.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_bottommost_compression_type(DBCompressionType::Zstd);
    /// opts.set_bottommost_compression_options(4, 5, 6, 7, true);
    /// ```
    pub fn set_bottommost_compression_options(
        &mut self,
        w_bits: c_int,
        level: c_int,
        strategy: c_int,
        max_dict_bytes: c_int,
        enabled: bool,
    ) {
        unsafe {
            ffi::rocksdb_options_set_bottommost_compression_options(
                self.inner,
                w_bits,
                level,
                strategy,
                max_dict_bytes,
                c_uchar::from(enabled),
            );
        }
    }

    /// Sets maximum size of training data passed to zstd's dictionary trainer. Using zstd's
    /// dictionary trainer can achieve even better compression ratio improvements than using
    /// `max_dict_bytes` alone.
    ///
    /// The training data will be used to generate a dictionary of max_dict_bytes.
    ///
    /// Default: 0.
    pub fn set_zstd_max_train_bytes(&mut self, value: c_int) {
        unsafe {
            ffi::rocksdb_options_set_compression_options_zstd_max_train_bytes(self.inner, value);
        }
    }

    /// Sets maximum size of training data passed to zstd's dictionary trainer
    /// when compressing the bottom-most level. Using zstd's dictionary trainer
    /// can achieve even better compression ratio improvements than using
    /// `max_dict_bytes` alone.
    ///
    /// The training data will be used to generate a dictionary of
    /// `max_dict_bytes`.
    ///
    /// Default: 0.
    pub fn set_bottommost_zstd_max_train_bytes(&mut self, value: c_int, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_bottommost_compression_options_zstd_max_train_bytes(
                self.inner,
                value,
                c_uchar::from(enabled),
            );
        }
    }

    /// If non-zero, we perform bigger reads when doing compaction. If you're
    /// running RocksDB on spinning disks, you should set this to at least 2MB.
    /// That way RocksDB's compaction is doing sequential instead of random reads.
    ///
    /// Default: 2 * 1024 * 1024 (2 MB)
    pub fn set_compaction_readahead_size(&mut self, compaction_readahead_size: usize) {
        unsafe {
            ffi::rocksdb_options_compaction_readahead_size(self.inner, compaction_readahead_size);
        }
    }

    /// Allow RocksDB to pick dynamic base of bytes for levels.
    /// With this feature turned on, RocksDB will automatically adjust max bytes for each level.
    /// The goal of this feature is to have lower bound on size amplification.
    ///
    /// Default: false.
    pub fn set_level_compaction_dynamic_level_bytes(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_options_set_level_compaction_dynamic_level_bytes(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// This option has different meanings for different compaction styles:
    ///
    /// Leveled: files older than `periodic_compaction_seconds` will be picked up
    /// for compaction and will be re-written to the same level as they were
    /// before.
    ///
    /// FIFO: not supported. Setting this option has no effect for FIFO compaction.
    ///
    /// Universal: when there are files older than `periodic_compaction_seconds`,
    /// rocksdb will try to do as large a compaction as possible including the
    /// last level. Such compaction is only skipped if only last level is to
    /// be compacted and no file in last level is older than
    /// `periodic_compaction_seconds`. See more in
    /// UniversalCompactionBuilder::PickPeriodicCompaction().
    /// For backward compatibility, the effective value of this option takes
    /// into account the value of option `ttl`. The logic is as follows:
    ///
    /// - both options are set to 30 days if they have the default value.
    /// - if both options are zero, zero is picked. Otherwise, we take the min
    ///   value among non-zero options values (i.e. takes the stricter limit).
    ///
    /// One main use of the feature is to make sure a file goes through compaction
    /// filters periodically. Users can also use the feature to clear up SST
    /// files using old format.
    ///
    /// A file's age is computed by looking at file_creation_time or creation_time
    /// table properties in order, if they have valid non-zero values; if not, the
    /// age is based on the file's last modified time (given by the underlying
    /// Env).
    ///
    /// This option only supports block based table format for any compaction
    /// style.
    ///
    /// unit: seconds. Ex: 7 days = 7 * 24 * 60 * 60
    ///
    /// Values:
    /// 0: Turn off Periodic compactions.
    /// UINT64_MAX - 1 (0xfffffffffffffffe) is special flag to allow RocksDB to
    /// pick default.
    ///
    /// Default: 30 days if using block based table format + compaction filter +
    /// leveled compaction or block based table format + universal compaction.
    /// 0 (disabled) otherwise.
    ///
    pub fn set_periodic_compaction_seconds(&mut self, secs: u64) {
        unsafe {
            ffi::rocksdb_options_set_periodic_compaction_seconds(self.inner, secs);
        }
    }

    pub fn set_merge_operator_associative<F: MergeFn + Clone>(
        &mut self,
        name: impl CStrLike,
        full_merge_fn: F,
    ) {
        let cb = Box::new(MergeOperatorCallback {
            name: name.into_c_string().unwrap(),
            full_merge_fn: full_merge_fn.clone(),
            partial_merge_fn: full_merge_fn,
        });

        unsafe {
            let mo = ffi::rocksdb_mergeoperator_create(
                Box::into_raw(cb).cast::<c_void>(),
                Some(merge_operator::destructor_callback::<F, F>),
                Some(full_merge_callback::<F, F>),
                Some(partial_merge_callback::<F, F>),
                Some(merge_operator::delete_callback),
                Some(merge_operator::name_callback::<F, F>),
            );
            ffi::rocksdb_options_set_merge_operator(self.inner, mo);
        }
    }

    pub fn set_merge_operator<F: MergeFn, PF: MergeFn>(
        &mut self,
        name: impl CStrLike,
        full_merge_fn: F,
        partial_merge_fn: PF,
    ) {
        let cb = Box::new(MergeOperatorCallback {
            name: name.into_c_string().unwrap(),
            full_merge_fn,
            partial_merge_fn,
        });

        unsafe {
            let mo = ffi::rocksdb_mergeoperator_create(
                Box::into_raw(cb).cast::<c_void>(),
                Some(merge_operator::destructor_callback::<F, PF>),
                Some(full_merge_callback::<F, PF>),
                Some(partial_merge_callback::<F, PF>),
                Some(merge_operator::delete_callback),
                Some(merge_operator::name_callback::<F, PF>),
            );
            ffi::rocksdb_options_set_merge_operator(self.inner, mo);
        }
    }

    #[deprecated(
        since = "0.5.0",
        note = "add_merge_operator has been renamed to set_merge_operator"
    )]
    pub fn add_merge_operator<F: MergeFn + Clone>(&mut self, name: &str, merge_fn: F) {
        self.set_merge_operator_associative(name, merge_fn);
    }

    /// Sets a compaction filter used to determine if entries should be kept, changed,
    /// or removed during compaction.
    ///
    /// An example use case is to remove entries with an expired TTL.
    ///
    /// If you take a snapshot of the database, only values written since the last
    /// snapshot will be passed through the compaction filter.
    ///
    /// If multi-threaded compaction is used, `filter_fn` may be called multiple times
    /// simultaneously.
    pub fn set_compaction_filter<F>(&mut self, name: impl CStrLike, filter_fn: F)
    where
        F: CompactionFilterFn + Send + 'static,
    {
        let cb = Box::new(CompactionFilterCallback {
            name: name.into_c_string().unwrap(),
            filter_fn,
        });

        unsafe {
            let cf = ffi::rocksdb_compactionfilter_create(
                Box::into_raw(cb).cast::<c_void>(),
                Some(compaction_filter::destructor_callback::<CompactionFilterCallback<F>>),
                Some(compaction_filter::filter_callback::<CompactionFilterCallback<F>>),
                Some(compaction_filter::name_callback::<CompactionFilterCallback<F>>),
            );
            ffi::rocksdb_options_set_compaction_filter(self.inner, cf);
        }
    }

    /// This is a factory that provides compaction filter objects which allow
    /// an application to modify/delete a key-value during background compaction.
    ///
    /// A new filter will be created on each compaction run.  If multithreaded
    /// compaction is being used, each created CompactionFilter will only be used
    /// from a single thread and so does not need to be thread-safe.
    ///
    /// Default: nullptr
    pub fn set_compaction_filter_factory<F>(&mut self, factory: F)
    where
        F: CompactionFilterFactory + 'static,
    {
        let factory = Box::new(factory);

        unsafe {
            let cff = ffi::rocksdb_compactionfilterfactory_create(
                Box::into_raw(factory).cast::<c_void>(),
                Some(compaction_filter_factory::destructor_callback::<F>),
                Some(compaction_filter_factory::create_compaction_filter_callback::<F>),
                Some(compaction_filter_factory::name_callback::<F>),
            );

            ffi::rocksdb_options_set_compaction_filter_factory(self.inner, cff);
        }
    }

    /// Sets the comparator used to define the order of keys in the table.
    /// Default: a comparator that uses lexicographic byte-wise ordering
    ///
    /// The client must ensure that the comparator supplied here has the same
    /// name and orders keys *exactly* the same as the comparator provided to
    /// previous open calls on the same DB.
    pub fn set_comparator(&mut self, name: impl CStrLike, compare_fn: Box<CompareFn>) {
        let cb = Box::new(ComparatorCallback {
            name: name.into_c_string().unwrap(),
            compare_fn,
        });

        unsafe {
            let cmp = ffi::rocksdb_comparator_create(
                Box::into_raw(cb).cast::<c_void>(),
                Some(ComparatorCallback::destructor_callback),
                Some(ComparatorCallback::compare_callback),
                Some(ComparatorCallback::name_callback),
            );
            ffi::rocksdb_options_set_comparator(self.inner, cmp);
        }
    }

    /// Sets the comparator that are timestamp-aware, used to define the order of keys in the table,
    /// taking timestamp into consideration.
    /// Find more information on timestamp-aware comparator on [here](https://github.com/facebook/rocksdb/wiki/User-defined-Timestamp)
    ///
    /// The client must ensure that the comparator supplied here has the same
    /// name and orders keys *exactly* the same as the comparator provided to
    /// previous open calls on the same DB.
    pub fn set_comparator_with_ts(
        &mut self,
        name: impl CStrLike,
        timestamp_size: usize,
        compare_fn: Box<CompareFn>,
        compare_ts_fn: Box<CompareTsFn>,
        compare_without_ts_fn: Box<CompareWithoutTsFn>,
    ) {
        let cb = Box::new(ComparatorWithTsCallback {
            name: name.into_c_string().unwrap(),
            compare_fn,
            compare_ts_fn,
            compare_without_ts_fn,
        });

        unsafe {
            let cmp = ffi::rocksdb_comparator_with_ts_create(
                Box::into_raw(cb).cast::<c_void>(),
                Some(ComparatorWithTsCallback::destructor_callback),
                Some(ComparatorWithTsCallback::compare_callback),
                Some(ComparatorWithTsCallback::compare_ts_callback),
                Some(ComparatorWithTsCallback::compare_without_ts_callback),
                Some(ComparatorWithTsCallback::name_callback),
                timestamp_size,
            );
            ffi::rocksdb_options_set_comparator(self.inner, cmp);
        }
    }

    pub fn set_prefix_extractor(&mut self, prefix_extractor: SliceTransform) {
        unsafe {
            ffi::rocksdb_options_set_prefix_extractor(self.inner, prefix_extractor.inner);
        }
    }

    // Use this if you don't need to keep the data sorted, i.e. you'll never use
    // an iterator, only Put() and Get() API calls
    //
    pub fn optimize_for_point_lookup(&mut self, block_cache_size_mb: u64) {
        unsafe {
            ffi::rocksdb_options_optimize_for_point_lookup(self.inner, block_cache_size_mb);
        }
    }

    /// Sets the optimize_filters_for_hits flag
    ///
    /// Default: `false`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_optimize_filters_for_hits(true);
    /// ```
    pub fn set_optimize_filters_for_hits(&mut self, optimize_for_hits: bool) {
        unsafe {
            ffi::rocksdb_options_set_optimize_filters_for_hits(
                self.inner,
                c_int::from(optimize_for_hits),
            );
        }
    }

    /// Sets the periodicity when obsolete files get deleted.
    ///
    /// The files that get out of scope by compaction
    /// process will still get automatically delete on every compaction,
    /// regardless of this setting.
    ///
    /// Default: 6 hours
    pub fn set_delete_obsolete_files_period_micros(&mut self, micros: u64) {
        unsafe {
            ffi::rocksdb_options_set_delete_obsolete_files_period_micros(self.inner, micros);
        }
    }

    /// Prepare the DB for bulk loading.
    ///
    /// All data will be in level 0 without any automatic compaction.
    /// It's recommended to manually call CompactRange(NULL, NULL) before reading
    /// from the database, because otherwise the read can be very slow.
    pub fn prepare_for_bulk_load(&mut self) {
        unsafe {
            ffi::rocksdb_options_prepare_for_bulk_load(self.inner);
        }
    }

    /// Sets the number of open files that can be used by the DB. You may need to
    /// increase this if your database has a large working set. Value `-1` means
    /// files opened are always kept open. You can estimate number of files based
    /// on target_file_size_base and target_file_size_multiplier for level-based
    /// compaction. For universal-style compaction, you can usually set it to `-1`.
    ///
    /// Default: `-1`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_max_open_files(10);
    /// ```
    pub fn set_max_open_files(&mut self, nfiles: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_open_files(self.inner, nfiles);
        }
    }

    /// If max_open_files is -1, DB will open all files on DB::Open(). You can
    /// use this option to increase the number of threads used to open the files.
    /// Default: 16
    pub fn set_max_file_opening_threads(&mut self, nthreads: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_file_opening_threads(self.inner, nthreads);
        }
    }

    /// By default, writes to stable storage use fdatasync (on platforms
    /// where this function is available). If this option is true,
    /// fsync is used instead.
    ///
    /// fsync and fdatasync are equally safe for our purposes and fdatasync is
    /// faster, so it is rarely necessary to set this option. It is provided
    /// as a workaround for kernel/filesystem bugs, such as one that affected
    /// fdatasync with ext4 in kernel versions prior to 3.7.
    ///
    /// Default: `false`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_use_fsync(true);
    /// ```
    pub fn set_use_fsync(&mut self, useit: bool) {
        unsafe {
            ffi::rocksdb_options_set_use_fsync(self.inner, c_int::from(useit));
        }
    }

    /// Returns the value of the `use_fsync` option.
    pub fn get_use_fsync(&self) -> bool {
        let val = unsafe { ffi::rocksdb_options_get_use_fsync(self.inner) };
        val != 0
    }

    /// Specifies the absolute info LOG dir.
    ///
    /// If it is empty, the log files will be in the same dir as data.
    /// If it is non empty, the log files will be in the specified dir,
    /// and the db data dir's absolute path will be used as the log file
    /// name's prefix.
    ///
    /// Default: empty
    pub fn set_db_log_dir<P: AsRef<Path>>(&mut self, path: P) {
        let p = to_cpath(path).unwrap();
        unsafe {
            ffi::rocksdb_options_set_db_log_dir(self.inner, p.as_ptr());
        }
    }

    /// Specifies the log level.
    /// Consider the `LogLevel` enum for a list of possible levels.
    ///
    /// Default: Info
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, LogLevel};
    ///
    /// let mut opts = Options::default();
    /// opts.set_log_level(LogLevel::Warn);
    /// ```
    pub fn set_log_level(&mut self, level: LogLevel) {
        unsafe {
            ffi::rocksdb_options_set_info_log_level(self.inner, level as c_int);
        }
    }

    /// Allows OS to incrementally sync files to disk while they are being
    /// written, asynchronously, in the background. This operation can be used
    /// to smooth out write I/Os over time. Users shouldn't rely on it for
    /// persistency guarantee.
    /// Issue one request for every bytes_per_sync written. `0` turns it off.
    ///
    /// Default: `0`
    ///
    /// You may consider using rate_limiter to regulate write rate to device.
    /// When rate limiter is enabled, it automatically enables bytes_per_sync
    /// to 1MB.
    ///
    /// This option applies to table files
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_bytes_per_sync(1024 * 1024);
    /// ```
    pub fn set_bytes_per_sync(&mut self, nbytes: u64) {
        unsafe {
            ffi::rocksdb_options_set_bytes_per_sync(self.inner, nbytes);
        }
    }

    /// Same as bytes_per_sync, but applies to WAL files.
    ///
    /// Default: 0, turned off
    ///
    /// Dynamically changeable through SetDBOptions() API.
    pub fn set_wal_bytes_per_sync(&mut self, nbytes: u64) {
        unsafe {
            ffi::rocksdb_options_set_wal_bytes_per_sync(self.inner, nbytes);
        }
    }

    /// Sets the maximum buffer size that is used by WritableFileWriter.
    ///
    /// On Windows, we need to maintain an aligned buffer for writes.
    /// We allow the buffer to grow until it's size hits the limit in buffered
    /// IO and fix the buffer size when using direct IO to ensure alignment of
    /// write requests if the logical sector size is unusual
    ///
    /// Default: 1024 * 1024 (1 MB)
    ///
    /// Dynamically changeable through SetDBOptions() API.
    pub fn set_writable_file_max_buffer_size(&mut self, nbytes: u64) {
        unsafe {
            ffi::rocksdb_options_set_writable_file_max_buffer_size(self.inner, nbytes);
        }
    }

    /// If true, allow multi-writers to update mem tables in parallel.
    /// Only some memtable_factory-s support concurrent writes; currently it
    /// is implemented only for SkipListFactory.  Concurrent memtable writes
    /// are not compatible with inplace_update_support or filter_deletes.
    /// It is strongly recommended to set enable_write_thread_adaptive_yield
    /// if you are going to use this feature.
    ///
    /// Default: true
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_allow_concurrent_memtable_write(false);
    /// ```
    pub fn set_allow_concurrent_memtable_write(&mut self, allow: bool) {
        unsafe {
            ffi::rocksdb_options_set_allow_concurrent_memtable_write(
                self.inner,
                c_uchar::from(allow),
            );
        }
    }

    /// If true, threads synchronizing with the write batch group leader will wait for up to
    /// write_thread_max_yield_usec before blocking on a mutex. This can substantially improve
    /// throughput for concurrent workloads, regardless of whether allow_concurrent_memtable_write
    /// is enabled.
    ///
    /// Default: true
    pub fn set_enable_write_thread_adaptive_yield(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_enable_write_thread_adaptive_yield(
                self.inner,
                c_uchar::from(enabled),
            );
        }
    }

    /// Specifies whether an iteration->Next() sequentially skips over keys with the same user-key or not.
    ///
    /// This number specifies the number of keys (with the same userkey)
    /// that will be sequentially skipped before a reseek is issued.
    ///
    /// Default: 8
    pub fn set_max_sequential_skip_in_iterations(&mut self, num: u64) {
        unsafe {
            ffi::rocksdb_options_set_max_sequential_skip_in_iterations(self.inner, num);
        }
    }

    /// Enable direct I/O mode for reading
    /// they may or may not improve performance depending on the use case
    ///
    /// Files will be opened in "direct I/O" mode
    /// which means that data read from the disk will not be cached or
    /// buffered. The hardware buffer of the devices may however still
    /// be used. Memory mapped files are not impacted by these parameters.
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_use_direct_reads(true);
    /// ```
    pub fn set_use_direct_reads(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_use_direct_reads(self.inner, c_uchar::from(enabled));
        }
    }

    /// Enable direct I/O mode for flush and compaction
    ///
    /// Files will be opened in "direct I/O" mode
    /// which means that data written to the disk will not be cached or
    /// buffered. The hardware buffer of the devices may however still
    /// be used. Memory mapped files are not impacted by these parameters.
    /// they may or may not improve performance depending on the use case
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_use_direct_io_for_flush_and_compaction(true);
    /// ```
    pub fn set_use_direct_io_for_flush_and_compaction(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_use_direct_io_for_flush_and_compaction(
                self.inner,
                c_uchar::from(enabled),
            );
        }
    }

    /// Enable/disable child process inherit open files.
    ///
    /// Default: true
    pub fn set_is_fd_close_on_exec(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_is_fd_close_on_exec(self.inner, c_uchar::from(enabled));
        }
    }

    /// Hints to the OS that it should not buffer disk I/O. Enabling this
    /// parameter may improve performance but increases pressure on the
    /// system cache.
    ///
    /// The exact behavior of this parameter is platform dependent.
    ///
    /// On POSIX systems, after RocksDB reads data from disk it will
    /// mark the pages as "unneeded". The operating system may or may not
    /// evict these pages from memory, reducing pressure on the system
    /// cache. If the disk block is requested again this can result in
    /// additional disk I/O.
    ///
    /// On WINDOWS systems, files will be opened in "unbuffered I/O" mode
    /// which means that data read from the disk will not be cached or
    /// bufferized. The hardware buffer of the devices may however still
    /// be used. Memory mapped files are not impacted by this parameter.
    ///
    /// Default: true
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// #[allow(deprecated)]
    /// opts.set_allow_os_buffer(false);
    /// ```
    #[deprecated(
        since = "0.7.0",
        note = "replaced with set_use_direct_reads/set_use_direct_io_for_flush_and_compaction methods"
    )]
    pub fn set_allow_os_buffer(&mut self, is_allow: bool) {
        self.set_use_direct_reads(!is_allow);
        self.set_use_direct_io_for_flush_and_compaction(!is_allow);
    }

    /// Sets the number of shards used for table cache.
    ///
    /// Default: `6`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_table_cache_num_shard_bits(4);
    /// ```
    pub fn set_table_cache_num_shard_bits(&mut self, nbits: c_int) {
        unsafe {
            ffi::rocksdb_options_set_table_cache_numshardbits(self.inner, nbits);
        }
    }

    /// By default target_file_size_multiplier is 1, which means
    /// by default files in different levels will have similar size.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_target_file_size_multiplier(&mut self, multiplier: i32) {
        unsafe {
            ffi::rocksdb_options_set_target_file_size_multiplier(self.inner, multiplier as c_int);
        }
    }

    /// Sets the minimum number of write buffers that will be merged
    /// before writing to storage.  If set to `1`, then
    /// all write buffers are flushed to L0 as individual files and this increases
    /// read amplification because a get request has to check in all of these
    /// files. Also, an in-memory merge may result in writing lesser
    /// data to storage if there are duplicate records in each of these
    /// individual write buffers.
    ///
    /// Default: `1`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_min_write_buffer_number(2);
    /// ```
    pub fn set_min_write_buffer_number(&mut self, nbuf: c_int) {
        unsafe {
            ffi::rocksdb_options_set_min_write_buffer_number_to_merge(self.inner, nbuf);
        }
    }

    /// Sets the maximum number of write buffers that are built up in memory.
    /// The default and the minimum number is 2, so that when 1 write buffer
    /// is being flushed to storage, new writes can continue to the other
    /// write buffer.
    /// If max_write_buffer_number > 3, writing will be slowed down to
    /// options.delayed_write_rate if we are writing to the last write buffer
    /// allowed.
    ///
    /// Default: `2`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_max_write_buffer_number(4);
    /// ```
    pub fn set_max_write_buffer_number(&mut self, nbuf: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_write_buffer_number(self.inner, nbuf);
        }
    }

    /// Sets the amount of data to build up in memory (backed by an unsorted log
    /// on disk) before converting to a sorted on-disk file.
    ///
    /// Larger values increase performance, especially during bulk loads.
    /// Up to max_write_buffer_number write buffers may be held in memory
    /// at the same time,
    /// so you may wish to adjust this parameter to control memory usage.
    /// Also, a larger write buffer will result in a longer recovery time
    /// the next time the database is opened.
    ///
    /// Note that write_buffer_size is enforced per column family.
    /// See db_write_buffer_size for sharing memory across column families.
    ///
    /// Default: `0x4000000` (64MiB)
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_write_buffer_size(128 * 1024 * 1024);
    /// ```
    pub fn set_write_buffer_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_write_buffer_size(self.inner, size);
        }
    }

    /// Amount of data to build up in memtables across all column
    /// families before writing to disk.
    ///
    /// This is distinct from write_buffer_size, which enforces a limit
    /// for a single memtable.
    ///
    /// This feature is disabled by default. Specify a non-zero value
    /// to enable it.
    ///
    /// Default: 0 (disabled)
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_db_write_buffer_size(128 * 1024 * 1024);
    /// ```
    pub fn set_db_write_buffer_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_db_write_buffer_size(self.inner, size);
        }
    }

    /// Control maximum total data size for a level.
    /// max_bytes_for_level_base is the max total for level-1.
    /// Maximum number of bytes for level L can be calculated as
    /// (max_bytes_for_level_base) * (max_bytes_for_level_multiplier ^ (L-1))
    /// For example, if max_bytes_for_level_base is 200MB, and if
    /// max_bytes_for_level_multiplier is 10, total data size for level-1
    /// will be 200MB, total file size for level-2 will be 2GB,
    /// and total file size for level-3 will be 20GB.
    ///
    /// Default: `0x10000000` (256MiB).
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_max_bytes_for_level_base(512 * 1024 * 1024);
    /// ```
    pub fn set_max_bytes_for_level_base(&mut self, size: u64) {
        unsafe {
            ffi::rocksdb_options_set_max_bytes_for_level_base(self.inner, size);
        }
    }

    /// Default: `10`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_max_bytes_for_level_multiplier(4.0);
    /// ```
    pub fn set_max_bytes_for_level_multiplier(&mut self, mul: f64) {
        unsafe {
            ffi::rocksdb_options_set_max_bytes_for_level_multiplier(self.inner, mul);
        }
    }

    /// The manifest file is rolled over on reaching this limit.
    /// The older manifest file be deleted.
    /// The default value is MAX_INT so that roll-over does not take place.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_max_manifest_file_size(20 * 1024 * 1024);
    /// ```
    pub fn set_max_manifest_file_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_max_manifest_file_size(self.inner, size);
        }
    }

    /// Sets the target file size for compaction.
    /// target_file_size_base is per-file size for level-1.
    /// Target file size for level L can be calculated by
    /// target_file_size_base * (target_file_size_multiplier ^ (L-1))
    /// For example, if target_file_size_base is 2MB and
    /// target_file_size_multiplier is 10, then each file on level-1 will
    /// be 2MB, and each file on level 2 will be 20MB,
    /// and each file on level-3 will be 200MB.
    ///
    /// Default: `0x4000000` (64MiB)
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_target_file_size_base(128 * 1024 * 1024);
    /// ```
    pub fn set_target_file_size_base(&mut self, size: u64) {
        unsafe {
            ffi::rocksdb_options_set_target_file_size_base(self.inner, size);
        }
    }

    /// Sets the minimum number of write buffers that will be merged together
    /// before writing to storage.  If set to `1`, then
    /// all write buffers are flushed to L0 as individual files and this increases
    /// read amplification because a get request has to check in all of these
    /// files. Also, an in-memory merge may result in writing lesser
    /// data to storage if there are duplicate records in each of these
    /// individual write buffers.
    ///
    /// Default: `1`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_min_write_buffer_number_to_merge(2);
    /// ```
    pub fn set_min_write_buffer_number_to_merge(&mut self, to_merge: c_int) {
        unsafe {
            ffi::rocksdb_options_set_min_write_buffer_number_to_merge(self.inner, to_merge);
        }
    }

    /// Sets the number of files to trigger level-0 compaction. A value < `0` means that
    /// level-0 compaction will not be triggered by number of files at all.
    ///
    /// Default: `4`
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_level_zero_file_num_compaction_trigger(8);
    /// ```
    pub fn set_level_zero_file_num_compaction_trigger(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_level0_file_num_compaction_trigger(self.inner, n);
        }
    }

    /// Sets the compaction priority. When multiple files are picked for compaction from a level,
    /// this option determines which files to pick first.
    ///
    /// Default: `CompactionPri::ByCompensatedSize`
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// See [rocksdb post](https://github.com/facebook/rocksdb/blob/f20d12adc85ece3e75fb238872959c702c0e5535/docs/_posts/2016-01-29-compaction_pri.markdown) for more details.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, CompactionPri};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compaction_pri(CompactionPri::MinOverlappingRatio);
    /// ```
    pub fn set_compaction_pri(&mut self, pri: CompactionPri) {
        unsafe {
            ffi::rocksdb_options_set_compaction_pri(self.inner, pri as i32);
        }
    }

    /// Sets the soft limit on number of level-0 files. We start slowing down writes at this
    /// point. A value < `0` means that no writing slowdown will be triggered by
    /// number of files in level-0.
    ///
    /// Default: `20`
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_level_zero_slowdown_writes_trigger(10);
    /// ```
    pub fn set_level_zero_slowdown_writes_trigger(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_level0_slowdown_writes_trigger(self.inner, n);
        }
    }

    /// Sets the maximum number of level-0 files.  We stop writes at this point.
    ///
    /// Default: `24`
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_level_zero_stop_writes_trigger(48);
    /// ```
    pub fn set_level_zero_stop_writes_trigger(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_level0_stop_writes_trigger(self.inner, n);
        }
    }

    /// Sets the compaction style.
    ///
    /// Default: DBCompactionStyle::Level
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompactionStyle};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compaction_style(DBCompactionStyle::Universal);
    /// ```
    pub fn set_compaction_style(&mut self, style: DBCompactionStyle) {
        unsafe {
            ffi::rocksdb_options_set_compaction_style(self.inner, style as c_int);
        }
    }

    /// Sets the options needed to support Universal Style compactions.
    pub fn set_universal_compaction_options(&mut self, uco: &UniversalCompactOptions) {
        unsafe {
            ffi::rocksdb_options_set_universal_compaction_options(self.inner, uco.inner);
        }
    }

    /// Sets the options for FIFO compaction style.
    pub fn set_fifo_compaction_options(&mut self, fco: &FifoCompactOptions) {
        unsafe {
            ffi::rocksdb_options_set_fifo_compaction_options(self.inner, fco.inner);
        }
    }

    /// Sets unordered_write to true trades higher write throughput with
    /// relaxing the immutability guarantee of snapshots. This violates the
    /// repeatability one expects from ::Get from a snapshot, as well as
    /// ::MultiGet and Iterator's consistent-point-in-time view property.
    /// If the application cannot tolerate the relaxed guarantees, it can implement
    /// its own mechanisms to work around that and yet benefit from the higher
    /// throughput. Using TransactionDB with WRITE_PREPARED write policy and
    /// two_write_queues=true is one way to achieve immutable snapshots despite
    /// unordered_write.
    ///
    /// By default, i.e., when it is false, rocksdb does not advance the sequence
    /// number for new snapshots unless all the writes with lower sequence numbers
    /// are already finished. This provides the immutability that we expect from
    /// snapshots. Moreover, since Iterator and MultiGet internally depend on
    /// snapshots, the snapshot immutability results into Iterator and MultiGet
    /// offering consistent-point-in-time view. If set to true, although
    /// Read-Your-Own-Write property is still provided, the snapshot immutability
    /// property is relaxed: the writes issued after the snapshot is obtained (with
    /// larger sequence numbers) will be still not visible to the reads from that
    /// snapshot, however, there still might be pending writes (with lower sequence
    /// number) that will change the state visible to the snapshot after they are
    /// landed to the memtable.
    ///
    /// Default: false
    pub fn set_unordered_write(&mut self, unordered: bool) {
        unsafe {
            ffi::rocksdb_options_set_unordered_write(self.inner, c_uchar::from(unordered));
        }
    }

    /// Sets maximum number of threads that will
    /// concurrently perform a compaction job by breaking it into multiple,
    /// smaller ones that are run simultaneously.
    ///
    /// Default: 1 (i.e. no subcompactions)
    pub fn set_max_subcompactions(&mut self, num: u32) {
        unsafe {
            ffi::rocksdb_options_set_max_subcompactions(self.inner, num);
        }
    }

    /// Sets maximum number of concurrent background jobs
    /// (compactions and flushes).
    ///
    /// Default: 2
    ///
    /// Dynamically changeable through SetDBOptions() API.
    pub fn set_max_background_jobs(&mut self, jobs: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_background_jobs(self.inner, jobs);
        }
    }

    /// Sets the maximum number of concurrent background compaction jobs, submitted to
    /// the default LOW priority thread pool.
    /// We first try to schedule compactions based on
    /// `base_background_compactions`. If the compaction cannot catch up , we
    /// will increase number of compaction threads up to
    /// `max_background_compactions`.
    ///
    /// If you're increasing this, also consider increasing number of threads in
    /// LOW priority thread pool. For more information, see
    /// Env::SetBackgroundThreads
    ///
    /// Default: `1`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// #[allow(deprecated)]
    /// opts.set_max_background_compactions(2);
    /// ```
    #[deprecated(
        since = "0.15.0",
        note = "RocksDB automatically decides this based on the value of max_background_jobs"
    )]
    pub fn set_max_background_compactions(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_background_compactions(self.inner, n);
        }
    }

    /// Sets the maximum number of concurrent background memtable flush jobs, submitted to
    /// the HIGH priority thread pool.
    ///
    /// By default, all background jobs (major compaction and memtable flush) go
    /// to the LOW priority pool. If this option is set to a positive number,
    /// memtable flush jobs will be submitted to the HIGH priority pool.
    /// It is important when the same Env is shared by multiple db instances.
    /// Without a separate pool, long running major compaction jobs could
    /// potentially block memtable flush jobs of other db instances, leading to
    /// unnecessary Put stalls.
    ///
    /// If you're increasing this, also consider increasing number of threads in
    /// HIGH priority thread pool. For more information, see
    /// Env::SetBackgroundThreads
    ///
    /// Default: `1`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// #[allow(deprecated)]
    /// opts.set_max_background_flushes(2);
    /// ```
    #[deprecated(
        since = "0.15.0",
        note = "RocksDB automatically decides this based on the value of max_background_jobs"
    )]
    pub fn set_max_background_flushes(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_max_background_flushes(self.inner, n);
        }
    }

    /// Disables automatic compactions. Manual compactions can still
    /// be issued on this column family
    ///
    /// Default: `false`
    ///
    /// Dynamically changeable through SetOptions() API
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_disable_auto_compactions(true);
    /// ```
    pub fn set_disable_auto_compactions(&mut self, disable: bool) {
        unsafe {
            ffi::rocksdb_options_set_disable_auto_compactions(self.inner, c_int::from(disable));
        }
    }

    /// SetMemtableHugePageSize sets the page size for huge page for
    /// arena used by the memtable.
    /// If <=0, it won't allocate from huge page but from malloc.
    /// Users are responsible to reserve huge pages for it to be allocated. For
    /// example:
    ///      sysctl -w vm.nr_hugepages=20
    /// See linux doc Documentation/vm/hugetlbpage.txt
    /// If there isn't enough free huge page available, it will fall back to
    /// malloc.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_memtable_huge_page_size(&mut self, size: size_t) {
        unsafe {
            ffi::rocksdb_options_set_memtable_huge_page_size(self.inner, size);
        }
    }

    /// Sets the maximum number of successive merge operations on a key in the memtable.
    ///
    /// When a merge operation is added to the memtable and the maximum number of
    /// successive merges is reached, the value of the key will be calculated and
    /// inserted into the memtable instead of the merge operation. This will
    /// ensure that there are never more than max_successive_merges merge
    /// operations in the memtable.
    ///
    /// Default: 0 (disabled)
    pub fn set_max_successive_merges(&mut self, num: usize) {
        unsafe {
            ffi::rocksdb_options_set_max_successive_merges(self.inner, num);
        }
    }

    /// Control locality of bloom filter probes to improve cache miss rate.
    /// This option only applies to memtable prefix bloom and plaintable
    /// prefix bloom. It essentially limits the max number of cache lines each
    /// bloom filter check can touch.
    ///
    /// This optimization is turned off when set to 0. The number should never
    /// be greater than number of probes. This option can boost performance
    /// for in-memory workload but should use with care since it can cause
    /// higher false positive rate.
    ///
    /// Default: 0
    pub fn set_bloom_locality(&mut self, v: u32) {
        unsafe {
            ffi::rocksdb_options_set_bloom_locality(self.inner, v);
        }
    }

    /// Enable/disable thread-safe inplace updates.
    ///
    /// Requires updates if
    /// * key exists in current memtable
    /// * new sizeof(new_value) <= sizeof(old_value)
    /// * old_value for that key is a put i.e. kTypeValue
    ///
    /// Default: false.
    pub fn set_inplace_update_support(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_inplace_update_support(self.inner, c_uchar::from(enabled));
        }
    }

    /// Sets the number of locks used for inplace update.
    ///
    /// Default: 10000 when inplace_update_support = true, otherwise 0.
    pub fn set_inplace_update_locks(&mut self, num: usize) {
        unsafe {
            ffi::rocksdb_options_set_inplace_update_num_locks(self.inner, num);
        }
    }

    /// Different max-size multipliers for different levels.
    /// These are multiplied by max_bytes_for_level_multiplier to arrive
    /// at the max-size of each level.
    ///
    /// Default: 1
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_max_bytes_for_level_multiplier_additional(&mut self, level_values: &[i32]) {
        let count = level_values.len();
        unsafe {
            ffi::rocksdb_options_set_max_bytes_for_level_multiplier_additional(
                self.inner,
                level_values.as_ptr().cast_mut(),
                count,
            );
        }
    }

    /// If true, then DB::Open() will not fetch and check sizes of all sst files.
    /// This may significantly speed up startup if there are many sst files,
    /// especially when using non-default Env with expensive GetFileSize().
    /// We'll still check that all required sst files exist.
    /// If paranoid_checks is false, this option is ignored, and sst files are
    /// not checked at all.
    ///
    /// Default: false
    #[deprecated(note = "RocksDB >= 10.5: option is ignored: checking done with a thread pool")]
    pub fn set_skip_checking_sst_file_sizes_on_db_open(&mut self, value: bool) {
        unsafe {
            ffi::rocksdb_options_set_skip_checking_sst_file_sizes_on_db_open(
                self.inner,
                c_uchar::from(value),
            );
        }
    }

    /// The total maximum size(bytes) of write buffers to maintain in memory
    /// including copies of buffers that have already been flushed. This parameter
    /// only affects trimming of flushed buffers and does not affect flushing.
    /// This controls the maximum amount of write history that will be available
    /// in memory for conflict checking when Transactions are used. The actual
    /// size of write history (flushed Memtables) might be higher than this limit
    /// if further trimming will reduce write history total size below this
    /// limit. For example, if max_write_buffer_size_to_maintain is set to 64MB,
    /// and there are three flushed Memtables, with sizes of 32MB, 20MB, 20MB.
    /// Because trimming the next Memtable of size 20MB will reduce total memory
    /// usage to 52MB which is below the limit, RocksDB will stop trimming.
    ///
    /// When using an OptimisticTransactionDB:
    /// If this value is too low, some transactions may fail at commit time due
    /// to not being able to determine whether there were any write conflicts.
    ///
    /// When using a TransactionDB:
    /// If Transaction::SetSnapshot is used, TransactionDB will read either
    /// in-memory write buffers or SST files to do write-conflict checking.
    /// Increasing this value can reduce the number of reads to SST files
    /// done for conflict detection.
    ///
    /// Setting this value to 0 will cause write buffers to be freed immediately
    /// after they are flushed. If this value is set to -1,
    /// 'max_write_buffer_number * write_buffer_size' will be used.
    ///
    /// Default:
    /// If using a TransactionDB/OptimisticTransactionDB, the default value will
    /// be set to the value of 'max_write_buffer_number * write_buffer_size'
    /// if it is not explicitly set by the user.  Otherwise, the default is 0.
    pub fn set_max_write_buffer_size_to_maintain(&mut self, size: i64) {
        unsafe {
            ffi::rocksdb_options_set_max_write_buffer_size_to_maintain(self.inner, size);
        }
    }

    /// By default, a single write thread queue is maintained. The thread gets
    /// to the head of the queue becomes write batch group leader and responsible
    /// for writing to WAL and memtable for the batch group.
    ///
    /// If enable_pipelined_write is true, separate write thread queue is
    /// maintained for WAL write and memtable write. A write thread first enter WAL
    /// writer queue and then memtable writer queue. Pending thread on the WAL
    /// writer queue thus only have to wait for previous writers to finish their
    /// WAL writing but not the memtable writing. Enabling the feature may improve
    /// write throughput and reduce latency of the prepare phase of two-phase
    /// commit.
    ///
    /// Default: false
    pub fn set_enable_pipelined_write(&mut self, value: bool) {
        unsafe {
            ffi::rocksdb_options_set_enable_pipelined_write(self.inner, c_uchar::from(value));
        }
    }

    /// Defines the underlying memtable implementation.
    /// See official [wiki](https://github.com/facebook/rocksdb/wiki/MemTable) for more information.
    /// Defaults to using a skiplist.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, MemtableFactory};
    /// let mut opts = Options::default();
    /// let factory = MemtableFactory::HashSkipList {
    ///     bucket_count: 1_000_000,
    ///     height: 4,
    ///     branching_factor: 4,
    /// };
    ///
    /// opts.set_allow_concurrent_memtable_write(false);
    /// opts.set_memtable_factory(factory);
    /// ```
    pub fn set_memtable_factory(&mut self, factory: MemtableFactory) {
        match factory {
            MemtableFactory::Vector => unsafe {
                ffi::rocksdb_options_set_memtable_vector_rep(self.inner);
            },
            MemtableFactory::HashSkipList {
                bucket_count,
                height,
                branching_factor,
            } => unsafe {
                ffi::rocksdb_options_set_hash_skip_list_rep(
                    self.inner,
                    bucket_count,
                    height,
                    branching_factor,
                );
            },
            MemtableFactory::HashLinkList { bucket_count } => unsafe {
                ffi::rocksdb_options_set_hash_link_list_rep(self.inner, bucket_count);
            },
        }
    }

    pub fn set_block_based_table_factory(&mut self, factory: &BlockBasedOptions) {
        unsafe {
            ffi::rocksdb_options_set_block_based_table_factory(self.inner, factory.inner);
        }
        self.outlive.block_based = Some(factory.outlive.clone());
    }

    /// Sets the table factory to a CuckooTableFactory (the default table
    /// factory is a block-based table factory that provides a default
    /// implementation of TableBuilder and TableReader with default
    /// BlockBasedTableOptions).
    /// See official [wiki](https://github.com/facebook/rocksdb/wiki/CuckooTable-Format) for more information on this table format.
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, CuckooTableOptions};
    ///
    /// let mut opts = Options::default();
    /// let mut factory_opts = CuckooTableOptions::default();
    /// factory_opts.set_hash_ratio(0.8);
    /// factory_opts.set_max_search_depth(20);
    /// factory_opts.set_cuckoo_block_size(10);
    /// factory_opts.set_identity_as_first_hash(true);
    /// factory_opts.set_use_module_hash(false);
    ///
    /// opts.set_cuckoo_table_factory(&factory_opts);
    /// ```
    pub fn set_cuckoo_table_factory(&mut self, factory: &CuckooTableOptions) {
        unsafe {
            ffi::rocksdb_options_set_cuckoo_table_factory(self.inner, factory.inner);
        }
    }

    // This is a factory that provides TableFactory objects.
    // Default: a block-based table factory that provides a default
    // implementation of TableBuilder and TableReader with default
    // BlockBasedTableOptions.
    /// Sets the factory as plain table.
    /// See official [wiki](https://github.com/facebook/rocksdb/wiki/PlainTable-Format) for more
    /// information.
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{KeyEncodingType, Options, PlainTableFactoryOptions};
    ///
    /// let mut opts = Options::default();
    /// let factory_opts = PlainTableFactoryOptions {
    ///   user_key_length: 0,
    ///   bloom_bits_per_key: 20,
    ///   hash_table_ratio: 0.75,
    ///   index_sparseness: 16,
    ///   huge_page_tlb_size: 0,
    ///   encoding_type: KeyEncodingType::Plain,
    ///   full_scan_mode: false,
    ///   store_index_in_file: false,
    /// };
    ///
    /// opts.set_plain_table_factory(&factory_opts);
    /// ```
    pub fn set_plain_table_factory(&mut self, options: &PlainTableFactoryOptions) {
        unsafe {
            ffi::rocksdb_options_set_plain_table_factory(
                self.inner,
                options.user_key_length,
                options.bloom_bits_per_key,
                options.hash_table_ratio,
                options.index_sparseness,
                options.huge_page_tlb_size,
                options.encoding_type as c_char,
                c_uchar::from(options.full_scan_mode),
                c_uchar::from(options.store_index_in_file),
            );
        }
    }

    /// Sets the start level to use compression.
    pub fn set_min_level_to_compress(&mut self, lvl: c_int) {
        unsafe {
            ffi::rocksdb_options_set_min_level_to_compress(self.inner, lvl);
        }
    }

    /// Measure IO stats in compactions and flushes, if `true`.
    ///
    /// Default: `false`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_report_bg_io_stats(true);
    /// ```
    pub fn set_report_bg_io_stats(&mut self, enable: bool) {
        unsafe {
            ffi::rocksdb_options_set_report_bg_io_stats(self.inner, c_int::from(enable));
        }
    }

    /// Once write-ahead logs exceed this size, we will start forcing the flush of
    /// column families whose memtables are backed by the oldest live WAL file
    /// (i.e. the ones that are causing all the space amplification).
    ///
    /// Default: `0`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// // Set max total wal size to 1G.
    /// opts.set_max_total_wal_size(1 << 30);
    /// ```
    pub fn set_max_total_wal_size(&mut self, size: u64) {
        unsafe {
            ffi::rocksdb_options_set_max_total_wal_size(self.inner, size);
        }
    }

    /// Recovery mode to control the consistency while replaying WAL.
    ///
    /// Default: DBRecoveryMode::PointInTime
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBRecoveryMode};
    ///
    /// let mut opts = Options::default();
    /// opts.set_wal_recovery_mode(DBRecoveryMode::AbsoluteConsistency);
    /// ```
    pub fn set_wal_recovery_mode(&mut self, mode: DBRecoveryMode) {
        unsafe {
            ffi::rocksdb_options_set_wal_recovery_mode(self.inner, mode as c_int);
        }
    }

    pub fn enable_statistics(&mut self) {
        unsafe {
            ffi::rocksdb_options_enable_statistics(self.inner);
        }
    }

    pub fn get_statistics(&self) -> Option<String> {
        unsafe {
            let value = ffi::rocksdb_options_statistics_get_string(self.inner);
            if value.is_null() {
                return None;
            }

            // Must have valid UTF-8 format.
            let s = CStr::from_ptr(value).to_str().unwrap().to_owned();
            ffi::rocksdb_free(value as *mut c_void);
            Some(s)
        }
    }

    /// StatsLevel can be used to reduce statistics overhead by skipping certain
    /// types of stats in the stats collection process.
    pub fn set_statistics_level(&self, level: StatsLevel) {
        unsafe { ffi::rocksdb_options_set_statistics_level(self.inner, level as c_int) }
    }

    /// Returns the value of cumulative db counters if stat collection is enabled.
    pub fn get_ticker_count(&self, ticker: Ticker) -> u64 {
        unsafe { ffi::rocksdb_options_statistics_get_ticker_count(self.inner, ticker as u32) }
    }

    /// Gets Histogram data from collected db stats. Requires stats to be enabled.
    pub fn get_histogram_data(&self, histogram: Histogram) -> HistogramData {
        unsafe {
            let data = HistogramData::default();
            ffi::rocksdb_options_statistics_get_histogram_data(
                self.inner,
                histogram as u32,
                data.inner,
            );
            data
        }
    }

    /// If not zero, dump `rocksdb.stats` to LOG every `stats_dump_period_sec`.
    ///
    /// Default: `600` (10 mins)
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_stats_dump_period_sec(300);
    /// ```
    pub fn set_stats_dump_period_sec(&mut self, period: c_uint) {
        unsafe {
            ffi::rocksdb_options_set_stats_dump_period_sec(self.inner, period);
        }
    }

    /// If not zero, dump rocksdb.stats to RocksDB to LOG every `stats_persist_period_sec`.
    ///
    /// Default: `600` (10 mins)
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_stats_persist_period_sec(5);
    /// ```
    pub fn set_stats_persist_period_sec(&mut self, period: c_uint) {
        unsafe {
            ffi::rocksdb_options_set_stats_persist_period_sec(self.inner, period);
        }
    }

    /// When set to true, reading SST files will opt out of the filesystem's
    /// readahead. Setting this to false may improve sequential iteration
    /// performance.
    ///
    /// Default: `true`
    pub fn set_advise_random_on_open(&mut self, advise: bool) {
        unsafe {
            ffi::rocksdb_options_set_advise_random_on_open(self.inner, c_uchar::from(advise));
        }
    }

    /// Enable/disable adaptive mutex, which spins in the user space before resorting to kernel.
    ///
    /// This could reduce context switch when the mutex is not
    /// heavily contended. However, if the mutex is hot, we could end up
    /// wasting spin time.
    ///
    /// Default: false
    pub fn set_use_adaptive_mutex(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_use_adaptive_mutex(self.inner, c_uchar::from(enabled));
        }
    }

    /// Sets the number of levels for this database.
    pub fn set_num_levels(&mut self, n: c_int) {
        unsafe {
            ffi::rocksdb_options_set_num_levels(self.inner, n);
        }
    }

    /// When a `prefix_extractor` is defined through `opts.set_prefix_extractor` this
    /// creates a prefix bloom filter for each memtable with the size of
    /// `write_buffer_size * memtable_prefix_bloom_ratio` (capped at 0.25).
    ///
    /// Default: `0`
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, SliceTransform};
    ///
    /// let mut opts = Options::default();
    /// let transform = SliceTransform::create_fixed_prefix(10);
    /// opts.set_prefix_extractor(transform);
    /// opts.set_memtable_prefix_bloom_ratio(0.2);
    /// ```
    pub fn set_memtable_prefix_bloom_ratio(&mut self, ratio: f64) {
        unsafe {
            ffi::rocksdb_options_set_memtable_prefix_bloom_size_ratio(self.inner, ratio);
        }
    }

    /// Sets the maximum number of bytes in all compacted files.
    /// We try to limit number of bytes in one compaction to be lower than this
    /// threshold. But it's not guaranteed.
    ///
    /// Value 0 will be sanitized.
    ///
    /// Default: target_file_size_base * 25
    pub fn set_max_compaction_bytes(&mut self, nbytes: u64) {
        unsafe {
            ffi::rocksdb_options_set_max_compaction_bytes(self.inner, nbytes);
        }
    }

    /// Specifies the absolute path of the directory the
    /// write-ahead log (WAL) should be written to.
    ///
    /// Default: same directory as the database
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut opts = Options::default();
    /// opts.set_wal_dir("/path/to/dir");
    /// ```
    pub fn set_wal_dir<P: AsRef<Path>>(&mut self, path: P) {
        let p = to_cpath(path).unwrap();
        unsafe {
            ffi::rocksdb_options_set_wal_dir(self.inner, p.as_ptr());
        }
    }

    /// Sets the WAL ttl in seconds.
    ///
    /// The following two options affect how archived logs will be deleted.
    /// 1. If both set to 0, logs will be deleted asap and will not get into
    ///    the archive.
    /// 2. If wal_ttl_seconds is 0 and wal_size_limit_mb is not 0,
    ///    WAL files will be checked every 10 min and if total size is greater
    ///    then wal_size_limit_mb, they will be deleted starting with the
    ///    earliest until size_limit is met. All empty files will be deleted.
    /// 3. If wal_ttl_seconds is not 0 and wall_size_limit_mb is 0, then
    ///    WAL files will be checked every wal_ttl_seconds / 2 and those that
    ///    are older than wal_ttl_seconds will be deleted.
    /// 4. If both are not 0, WAL files will be checked every 10 min and both
    ///    checks will be performed with ttl being first.
    ///
    /// Default: 0
    pub fn set_wal_ttl_seconds(&mut self, secs: u64) {
        unsafe {
            ffi::rocksdb_options_set_WAL_ttl_seconds(self.inner, secs);
        }
    }

    /// Sets the WAL size limit in MB.
    ///
    /// If total size of WAL files is greater then wal_size_limit_mb,
    /// they will be deleted starting with the earliest until size_limit is met.
    ///
    /// Default: 0
    pub fn set_wal_size_limit_mb(&mut self, size: u64) {
        unsafe {
            ffi::rocksdb_options_set_WAL_size_limit_MB(self.inner, size);
        }
    }

    /// Sets the number of bytes to preallocate (via fallocate) the manifest files.
    ///
    /// Default is 4MB, which is reasonable to reduce random IO
    /// as well as prevent overallocation for mounts that preallocate
    /// large amounts of data (such as xfs's allocsize option).
    pub fn set_manifest_preallocation_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_manifest_preallocation_size(self.inner, size);
        }
    }

    /// If true, then DB::Open() will not update the statistics used to optimize
    /// compaction decision by loading table properties from many files.
    /// Turning off this feature will improve DBOpen time especially in disk environment.
    ///
    /// Default: false
    pub fn set_skip_stats_update_on_db_open(&mut self, skip: bool) {
        unsafe {
            ffi::rocksdb_options_set_skip_stats_update_on_db_open(self.inner, c_uchar::from(skip));
        }
    }

    /// Specify the maximal number of info log files to be kept.
    ///
    /// Default: 1000
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_keep_log_file_num(100);
    /// ```
    pub fn set_keep_log_file_num(&mut self, nfiles: usize) {
        unsafe {
            ffi::rocksdb_options_set_keep_log_file_num(self.inner, nfiles);
        }
    }

    /// Allow the OS to mmap file for writing.
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_allow_mmap_writes(true);
    /// ```
    pub fn set_allow_mmap_writes(&mut self, is_enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_allow_mmap_writes(self.inner, c_uchar::from(is_enabled));
        }
    }

    /// Allow the OS to mmap file for reading sst tables.
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_allow_mmap_reads(true);
    /// ```
    pub fn set_allow_mmap_reads(&mut self, is_enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_allow_mmap_reads(self.inner, c_uchar::from(is_enabled));
        }
    }

    /// If enabled, WAL is not flushed automatically after each write. Instead it
    /// relies on manual invocation of `DB::flush_wal()` to write the WAL buffer
    /// to its file.
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_manual_wal_flush(true);
    /// ```
    pub fn set_manual_wal_flush(&mut self, is_enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_manual_wal_flush(self.inner, c_uchar::from(is_enabled));
        }
    }

    /// Guarantee that all column families are flushed together atomically.
    /// This option applies to both manual flushes (`db.flush()`) and automatic
    /// background flushes caused when memtables are filled.
    ///
    /// Note that this is only useful when the WAL is disabled. When using the
    /// WAL, writes are always consistent across column families.
    ///
    /// Default: false
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_atomic_flush(true);
    /// ```
    pub fn set_atomic_flush(&mut self, atomic_flush: bool) {
        unsafe {
            ffi::rocksdb_options_set_atomic_flush(self.inner, c_uchar::from(atomic_flush));
        }
    }

    /// Sets global cache for table-level rows.
    ///
    /// Default: null (disabled)
    /// Not supported in ROCKSDB_LITE mode!
    pub fn set_row_cache(&mut self, cache: &Cache) {
        unsafe {
            ffi::rocksdb_options_set_row_cache(self.inner, cache.0.inner.as_ptr());
        }
        self.outlive.row_cache = Some(cache.clone());
    }

    /// Use to control write rate of flush and compaction. Flush has higher
    /// priority than compaction.
    /// If rate limiter is enabled, bytes_per_sync is set to 1MB by default.
    ///
    /// Default: disable
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_ratelimiter(1024 * 1024, 100 * 1000, 10);
    /// ```
    pub fn set_ratelimiter(
        &mut self,
        rate_bytes_per_sec: i64,
        refill_period_us: i64,
        fairness: i32,
    ) {
        unsafe {
            let ratelimiter =
                ffi::rocksdb_ratelimiter_create(rate_bytes_per_sec, refill_period_us, fairness);
            ffi::rocksdb_options_set_ratelimiter(self.inner, ratelimiter);
            ffi::rocksdb_ratelimiter_destroy(ratelimiter);
        }
    }

    /// Use to control write rate of flush and compaction. Flush has higher
    /// priority than compaction.
    /// If rate limiter is enabled, bytes_per_sync is set to 1MB by default.
    ///
    /// Default: disable
    pub fn set_auto_tuned_ratelimiter(
        &mut self,
        rate_bytes_per_sec: i64,
        refill_period_us: i64,
        fairness: i32,
    ) {
        unsafe {
            let ratelimiter = ffi::rocksdb_ratelimiter_create_auto_tuned(
                rate_bytes_per_sec,
                refill_period_us,
                fairness,
            );
            ffi::rocksdb_options_set_ratelimiter(self.inner, ratelimiter);
            ffi::rocksdb_ratelimiter_destroy(ratelimiter);
        }
    }

    /// Sets the maximal size of the info log file.
    ///
    /// If the log file is larger than `max_log_file_size`, a new info log file
    /// will be created. If `max_log_file_size` is equal to zero, all logs will
    /// be written to one log file.
    ///
    /// Default: 0
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_max_log_file_size(0);
    /// ```
    pub fn set_max_log_file_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_max_log_file_size(self.inner, size);
        }
    }

    /// Sets the time for the info log file to roll (in seconds).
    ///
    /// If specified with non-zero value, log file will be rolled
    /// if it has been active longer than `log_file_time_to_roll`.
    /// Default: 0 (disabled)
    pub fn set_log_file_time_to_roll(&mut self, secs: usize) {
        unsafe {
            ffi::rocksdb_options_set_log_file_time_to_roll(self.inner, secs);
        }
    }

    /// Controls the recycling of log files.
    ///
    /// If non-zero, previously written log files will be reused for new logs,
    /// overwriting the old data. The value indicates how many such files we will
    /// keep around at any point in time for later use. This is more efficient
    /// because the blocks are already allocated and fdatasync does not need to
    /// update the inode after each write.
    ///
    /// Default: 0
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::Options;
    ///
    /// let mut options = Options::default();
    /// options.set_recycle_log_file_num(5);
    /// ```
    pub fn set_recycle_log_file_num(&mut self, num: usize) {
        unsafe {
            ffi::rocksdb_options_set_recycle_log_file_num(self.inner, num);
        }
    }

    /// Sets the threshold at which all writes will be slowed down to at least delayed_write_rate if estimated
    /// bytes needed to be compaction exceed this threshold.
    ///
    /// Default: 64GB
    pub fn set_soft_pending_compaction_bytes_limit(&mut self, limit: usize) {
        unsafe {
            ffi::rocksdb_options_set_soft_pending_compaction_bytes_limit(self.inner, limit);
        }
    }

    /// Sets the bytes threshold at which all writes are stopped if estimated bytes needed to be compaction exceed
    /// this threshold.
    ///
    /// Default: 256GB
    pub fn set_hard_pending_compaction_bytes_limit(&mut self, limit: usize) {
        unsafe {
            ffi::rocksdb_options_set_hard_pending_compaction_bytes_limit(self.inner, limit);
        }
    }

    /// Sets the size of one block in arena memory allocation.
    ///
    /// If <= 0, a proper value is automatically calculated (usually 1/10 of
    /// writer_buffer_size).
    ///
    /// Default: 0
    pub fn set_arena_block_size(&mut self, size: usize) {
        unsafe {
            ffi::rocksdb_options_set_arena_block_size(self.inner, size);
        }
    }

    /// If true, then print malloc stats together with rocksdb.stats when printing to LOG.
    ///
    /// Default: false
    pub fn set_dump_malloc_stats(&mut self, enabled: bool) {
        unsafe {
            ffi::rocksdb_options_set_dump_malloc_stats(self.inner, c_uchar::from(enabled));
        }
    }

    /// Enable whole key bloom filter in memtable. Note this will only take effect
    /// if memtable_prefix_bloom_size_ratio is not 0. Enabling whole key filtering
    /// can potentially reduce CPU usage for point-look-ups.
    ///
    /// Default: false (disable)
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_memtable_whole_key_filtering(&mut self, whole_key_filter: bool) {
        unsafe {
            ffi::rocksdb_options_set_memtable_whole_key_filtering(
                self.inner,
                c_uchar::from(whole_key_filter),
            );
        }
    }

    /// Enable the use of key-value separation.
    ///
    /// More details can be found here: [Integrated BlobDB](http://rocksdb.org/blog/2021/05/26/integrated-blob-db.html).
    ///
    /// Default: false (disable)
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_enable_blob_files(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_enable_blob_files(self.inner, u8::from(val));
        }
    }

    /// Sets the minimum threshold value at or above which will be written
    /// to blob files during flush or compaction.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_min_blob_size(&mut self, val: u64) {
        unsafe {
            ffi::rocksdb_options_set_min_blob_size(self.inner, val);
        }
    }

    /// Sets the size limit for blob files.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_blob_file_size(&mut self, val: u64) {
        unsafe {
            ffi::rocksdb_options_set_blob_file_size(self.inner, val);
        }
    }

    /// Sets the blob compression type. All blob files use the same
    /// compression type.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_blob_compression_type(&mut self, val: DBCompressionType) {
        unsafe {
            ffi::rocksdb_options_set_blob_compression_type(self.inner, val as _);
        }
    }

    /// If this is set to true RocksDB will actively relocate valid blobs from the oldest blob files
    /// as they are encountered during compaction.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_enable_blob_gc(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_enable_blob_gc(self.inner, u8::from(val));
        }
    }

    /// Sets the threshold that the GC logic uses to determine which blob files should be considered “old.”
    ///
    /// For example, the default value of 0.25 signals to RocksDB that blobs residing in the
    /// oldest 25% of blob files should be relocated by GC. This parameter can be tuned to adjust
    /// the trade-off between write amplification and space amplification.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_blob_gc_age_cutoff(&mut self, val: c_double) {
        unsafe {
            ffi::rocksdb_options_set_blob_gc_age_cutoff(self.inner, val);
        }
    }

    /// Sets the blob GC force threshold.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_blob_gc_force_threshold(&mut self, val: c_double) {
        unsafe {
            ffi::rocksdb_options_set_blob_gc_force_threshold(self.inner, val);
        }
    }

    /// Sets the blob compaction read ahead size.
    ///
    /// Dynamically changeable through SetOptions() API
    pub fn set_blob_compaction_readahead_size(&mut self, val: u64) {
        unsafe {
            ffi::rocksdb_options_set_blob_compaction_readahead_size(self.inner, val);
        }
    }

    /// Sets the blob cache.
    ///
    /// Using a dedicated object for blobs and using the same object for the block and blob caches
    /// are both supported. In the latter case, note that blobs are less valuable from a caching
    /// perspective than SST blocks, and some cache implementations have configuration options that
    /// can be used to prioritize items accordingly (see Cache::Priority and
    /// LRUCacheOptions::{high,low}_pri_pool_ratio).
    ///
    /// Default: disabled
    pub fn set_blob_cache(&mut self, cache: &Cache) {
        unsafe {
            ffi::rocksdb_options_set_blob_cache(self.inner, cache.0.inner.as_ptr());
        }
        self.outlive.blob_cache = Some(cache.clone());
    }

    /// Set this option to true during creation of database if you want
    /// to be able to ingest behind (call IngestExternalFile() skipping keys
    /// that already exist, rather than overwriting matching keys).
    /// Setting this option to true has the following effects:
    ///
    /// 1. Disable some internal optimizations around SST file compression.
    /// 2. Reserve the last level for ingested files only.
    /// 3. Compaction will not include any file from the last level.
    ///
    /// Note that only Universal Compaction supports allow_ingest_behind.
    /// `num_levels` should be >= 3 if this option is turned on.
    ///
    /// DEFAULT: false
    /// Immutable.
    pub fn set_allow_ingest_behind(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_allow_ingest_behind(self.inner, c_uchar::from(val));
        }
    }

    // A factory of a table property collector that marks an SST
    // file as need-compaction when it observe at least "D" deletion
    // entries in any "N" consecutive entries, or the ratio of tombstone
    // entries >= deletion_ratio.
    //
    // `window_size`: is the sliding window size "N"
    // `num_dels_trigger`: is the deletion trigger "D"
    // `deletion_ratio`: if <= 0 or > 1, disable triggering compaction based on
    // deletion ratio.
    pub fn add_compact_on_deletion_collector_factory(
        &mut self,
        window_size: size_t,
        num_dels_trigger: size_t,
        deletion_ratio: f64,
    ) {
        unsafe {
            ffi::rocksdb_options_add_compact_on_deletion_collector_factory_del_ratio(
                self.inner,
                window_size,
                num_dels_trigger,
                deletion_ratio,
            );
        }
    }

    /// <https://github.com/facebook/rocksdb/wiki/Write-Buffer-Manager>
    /// Write buffer manager helps users control the total memory used by memtables across multiple column families and/or DB instances.
    /// Users can enable this control by 2 ways:
    ///
    /// 1- Limit the total memtable usage across multiple column families and DBs under a threshold.
    /// 2- Cost the memtable memory usage to block cache so that memory of RocksDB can be capped by the single limit.
    /// The usage of a write buffer manager is similar to rate_limiter and sst_file_manager.
    /// Users can create one write buffer manager object and pass it to all the options of column families or DBs whose memtable size they want to be controlled by this object.
    pub fn set_write_buffer_manager(&mut self, write_buffer_manager: &WriteBufferManager) {
        unsafe {
            ffi::rocksdb_options_set_write_buffer_manager(
                self.inner,
                write_buffer_manager.0.inner.as_ptr(),
            );
        }
        self.outlive.write_buffer_manager = Some(write_buffer_manager.clone());
    }

    /// If true, working thread may avoid doing unnecessary and long-latency
    /// operation (such as deleting obsolete files directly or deleting memtable)
    /// and will instead schedule a background job to do it.
    ///
    /// Use it if you're latency-sensitive.
    ///
    /// Default: false (disabled)
    pub fn set_avoid_unnecessary_blocking_io(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_avoid_unnecessary_blocking_io(self.inner, u8::from(val));
        }
    }

    /// If true, the log numbers and sizes of the synced WALs are tracked
    /// in MANIFEST. During DB recovery, if a synced WAL is missing
    /// from disk, or the WAL's size does not match the recorded size in
    /// MANIFEST, an error will be reported and the recovery will be aborted.
    ///
    /// This is one additional protection against WAL corruption besides the
    /// per-WAL-entry checksum.
    ///
    /// Note that this option does not work with secondary instance.
    /// Currently, only syncing closed WALs are tracked. Calling `DB::SyncWAL()`,
    /// etc. or writing with `WriteOptions::sync=true` to sync the live WAL is not
    /// tracked for performance/efficiency reasons.
    ///
    /// See: <https://github.com/facebook/rocksdb/wiki/Track-WAL-in-MANIFEST>
    ///
    /// Default: false (disabled)
    pub fn set_track_and_verify_wals_in_manifest(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_track_and_verify_wals_in_manifest(self.inner, u8::from(val));
        }
    }

    /// Returns the value of the `track_and_verify_wals_in_manifest` option.
    pub fn get_track_and_verify_wals_in_manifest(&self) -> bool {
        let val_u8 =
            unsafe { ffi::rocksdb_options_get_track_and_verify_wals_in_manifest(self.inner) };
        val_u8 != 0
    }

    /// The DB unique ID can be saved in the DB manifest (preferred, this option)
    /// or an IDENTITY file (historical, deprecated), or both. If this option is
    /// set to false (old behavior), then `write_identity_file` must be set to true.
    /// The manifest is preferred because
    ///
    /// 1. The IDENTITY file is not checksummed, so it is not as safe against
    ///    corruption.
    /// 2. The IDENTITY file may or may not be copied with the DB (e.g. not
    ///    copied by BackupEngine), so is not reliable for the provenance of a DB.
    ///
    /// This option might eventually be obsolete and removed as Identity files
    /// are phased out.
    ///
    /// Default: true (enabled)
    pub fn set_write_dbid_to_manifest(&mut self, val: bool) {
        unsafe {
            ffi::rocksdb_options_set_write_dbid_to_manifest(self.inner, u8::from(val));
        }
    }

    /// Returns the value of the `write_dbid_to_manifest` option.
    pub fn get_write_dbid_to_manifest(&self) -> bool {
        let val_u8 = unsafe { ffi::rocksdb_options_get_write_dbid_to_manifest(self.inner) };
        val_u8 != 0
    }
}

impl Default for Options {
    fn default() -> Self {
        unsafe {
            let opts = ffi::rocksdb_options_create();
            assert!(!opts.is_null(), "Could not create RocksDB options");

            Self {
                inner: opts,
                outlive: OptionsMustOutliveDB::default(),
            }
        }
    }
}

impl FlushOptions {
    pub fn new() -> FlushOptions {
        FlushOptions::default()
    }

    /// Waits until the flush is done.
    ///
    /// Default: true
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::FlushOptions;
    ///
    /// let mut options = FlushOptions::default();
    /// options.set_wait(false);
    /// ```
    pub fn set_wait(&mut self, wait: bool) {
        unsafe {
            ffi::rocksdb_flushoptions_set_wait(self.inner, c_uchar::from(wait));
        }
    }
}

impl Default for FlushOptions {
    fn default() -> Self {
        let flush_opts = unsafe { ffi::rocksdb_flushoptions_create() };
        assert!(
            !flush_opts.is_null(),
            "Could not create RocksDB flush options"
        );

        Self { inner: flush_opts }
    }
}

impl WriteOptions {
    pub fn new() -> WriteOptions {
        WriteOptions::default()
    }

    /// Sets the sync mode. If true, the write will be flushed
    /// from the operating system buffer cache before the write is considered complete.
    /// If this flag is true, writes will be slower.
    ///
    /// Default: false
    pub fn set_sync(&mut self, sync: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_set_sync(self.inner, c_uchar::from(sync));
        }
    }

    /// Sets whether WAL should be active or not.
    /// If true, writes will not first go to the write ahead log,
    /// and the write may got lost after a crash.
    ///
    /// Default: false
    pub fn disable_wal(&mut self, disable: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_disable_WAL(self.inner, c_int::from(disable));
        }
    }

    /// If true and if user is trying to write to column families that don't exist (they were dropped),
    /// ignore the write (don't return an error). If there are multiple writes in a WriteBatch,
    /// other writes will succeed.
    ///
    /// Default: false
    pub fn set_ignore_missing_column_families(&mut self, ignore: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_set_ignore_missing_column_families(
                self.inner,
                c_uchar::from(ignore),
            );
        }
    }

    /// If true and we need to wait or sleep for the write request, fails
    /// immediately with Status::Incomplete().
    ///
    /// Default: false
    pub fn set_no_slowdown(&mut self, no_slowdown: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_set_no_slowdown(self.inner, c_uchar::from(no_slowdown));
        }
    }

    /// If true, this write request is of lower priority if compaction is
    /// behind. In this case, no_slowdown = true, the request will be cancelled
    /// immediately with Status::Incomplete() returned. Otherwise, it will be
    /// slowed down. The slowdown value is determined by RocksDB to guarantee
    /// it introduces minimum impacts to high priority writes.
    ///
    /// Default: false
    pub fn set_low_pri(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_set_low_pri(self.inner, c_uchar::from(v));
        }
    }

    /// If true, writebatch will maintain the last insert positions of each
    /// memtable as hints in concurrent write. It can improve write performance
    /// in concurrent writes if keys in one writebatch are sequential. In
    /// non-concurrent writes (when concurrent_memtable_writes is false) this
    /// option will be ignored.
    ///
    /// Default: false
    pub fn set_memtable_insert_hint_per_batch(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_writeoptions_set_memtable_insert_hint_per_batch(
                self.inner,
                c_uchar::from(v),
            );
        }
    }
}

impl Default for WriteOptions {
    fn default() -> Self {
        let write_opts = unsafe { ffi::rocksdb_writeoptions_create() };
        assert!(
            !write_opts.is_null(),
            "Could not create RocksDB write options"
        );

        Self { inner: write_opts }
    }
}

impl LruCacheOptions {
    /// Capacity of the cache, in the same units as the `charge` of each entry.
    /// This is typically measured in bytes, but can be a different unit if using
    /// kDontChargeCacheMetadata.
    pub fn set_capacity(&mut self, cap: usize) {
        unsafe {
            ffi::rocksdb_lru_cache_options_set_capacity(self.inner, cap);
        }
    }

    /// Cache is sharded into 2^num_shard_bits shards, by hash of key.
    /// If < 0, a good default is chosen based on the capacity and the
    /// implementation. (Mutex-based implementations are much more reliant
    /// on many shards for parallel scalability.)
    pub fn set_num_shard_bits(&mut self, val: c_int) {
        unsafe {
            ffi::rocksdb_lru_cache_options_set_num_shard_bits(self.inner, val);
        }
    }
}

impl Default for LruCacheOptions {
    fn default() -> Self {
        let inner = unsafe { ffi::rocksdb_lru_cache_options_create() };
        assert!(
            !inner.is_null(),
            "Could not create RocksDB LRU cache options"
        );

        Self { inner }
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
#[repr(i32)]
pub enum ReadTier {
    /// Reads data in memtable, block cache, OS cache or storage.
    All = 0,
    /// Reads data in memtable or block cache.
    BlockCache,
    /// Reads persisted data. When WAL is disabled, this option will skip data in memtable.
    Persisted,
    /// Reads data in memtable. Used for memtable only iterators.
    Memtable,
}

#[repr(i32)]
pub enum CompactionPri {
    /// Slightly prioritize larger files by size compensated by #deletes
    ByCompensatedSize = 0,
    /// First compact files whose data's latest update time is oldest.
    /// Try this if you only update some hot keys in small ranges.
    OldestLargestSeqFirst = 1,
    /// First compact files whose range hasn't been compacted to the next level
    /// for the longest. If your updates are random across the key space,
    /// write amplification is slightly better with this option.
    OldestSmallestSeqFirst = 2,
    /// First compact files whose ratio between overlapping size in next level
    /// and its size is the smallest. It in many cases can optimize write amplification.
    MinOverlappingRatio = 3,
    /// Keeps a cursor(s) of the successor of the file (key range) was/were
    /// compacted before, and always picks the next files (key range) in that
    /// level. The file picking process will cycle through all the files in a
    /// round-robin manner.
    RoundRobin = 4,
}

impl ReadOptions {
    // TODO add snapshot setting here
    // TODO add snapshot wrapper structs with proper destructors;
    // that struct needs an "iterator" impl too.

    /// Specify whether the "data block"/"index block"/"filter block"
    /// read for this iteration should be cached in memory?
    /// Callers may wish to set this field to false for bulk scans.
    ///
    /// Default: true
    pub fn fill_cache(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_fill_cache(self.inner, c_uchar::from(v));
        }
    }

    /// Sets the snapshot which should be used for the read.
    /// The snapshot must belong to the DB that is being read and must
    /// not have been released.
    pub fn set_snapshot<D: DBAccess>(&mut self, snapshot: &SnapshotWithThreadMode<D>) {
        unsafe {
            ffi::rocksdb_readoptions_set_snapshot(self.inner, snapshot.inner);
        }
    }

    /// Sets the lower bound for an iterator.
    pub fn set_iterate_lower_bound<K: Into<Vec<u8>>>(&mut self, key: K) {
        self.set_lower_bound_impl(Some(key.into()));
    }

    /// Sets the upper bound for an iterator.
    /// The upper bound itself is not included on the iteration result.
    pub fn set_iterate_upper_bound<K: Into<Vec<u8>>>(&mut self, key: K) {
        self.set_upper_bound_impl(Some(key.into()));
    }

    /// Sets lower and upper bounds based on the provided range.  This is
    /// similar to setting lower and upper bounds separately except that it also
    /// allows either bound to be reset.
    ///
    /// The argument can be a regular Rust range, e.g. `lower..upper`.  However,
    /// since RocksDB upper bound is always excluded (i.e. range can never be
    /// fully closed) inclusive ranges (`lower..=upper` and `..=upper`) are not
    /// supported.  For example:
    ///
    /// ```
    /// let mut options = rocksdb::ReadOptions::default();
    /// options.set_iterate_range("xy".as_bytes().."xz".as_bytes());
    /// ```
    ///
    /// In addition, [`crate::PrefixRange`] can be used to specify a range of
    /// keys with a given prefix.  In particular, the above example is
    /// equivalent to:
    ///
    /// ```
    /// let mut options = rocksdb::ReadOptions::default();
    /// options.set_iterate_range(rocksdb::PrefixRange("xy".as_bytes()));
    /// ```
    ///
    /// Note that setting range using this method is separate to using prefix
    /// iterators.  Prefix iterators use prefix extractor configured for
    /// a column family.  Setting bounds via [`crate::PrefixRange`] is more akin
    /// to using manual prefix.
    ///
    /// Using this method clears any previously set bounds.  In other words, the
    /// bounds can be reset by setting the range to `..` as in:
    ///
    /// ```
    /// let mut options = rocksdb::ReadOptions::default();
    /// options.set_iterate_range(..);
    /// ```
    pub fn set_iterate_range(&mut self, range: impl crate::IterateBounds) {
        let (lower, upper) = range.into_bounds();
        self.set_lower_bound_impl(lower);
        self.set_upper_bound_impl(upper);
    }

    fn set_lower_bound_impl(&mut self, bound: Option<Vec<u8>>) {
        let (ptr, len) = if let Some(ref bound) = bound {
            (bound.as_ptr() as *const c_char, bound.len())
        } else if self.iterate_lower_bound.is_some() {
            (std::ptr::null(), 0)
        } else {
            return;
        };
        self.iterate_lower_bound = bound;
        unsafe {
            ffi::rocksdb_readoptions_set_iterate_lower_bound(self.inner, ptr, len);
        }
    }

    fn set_upper_bound_impl(&mut self, bound: Option<Vec<u8>>) {
        let (ptr, len) = if let Some(ref bound) = bound {
            (bound.as_ptr() as *const c_char, bound.len())
        } else if self.iterate_upper_bound.is_some() {
            (std::ptr::null(), 0)
        } else {
            return;
        };
        self.iterate_upper_bound = bound;
        unsafe {
            ffi::rocksdb_readoptions_set_iterate_upper_bound(self.inner, ptr, len);
        }
    }

    /// Specify if this read request should process data that ALREADY
    /// resides on a particular cache. If the required data is not
    /// found at the specified cache, then Status::Incomplete is returned.
    ///
    /// Default: ::All
    pub fn set_read_tier(&mut self, tier: ReadTier) {
        unsafe {
            ffi::rocksdb_readoptions_set_read_tier(self.inner, tier as c_int);
        }
    }

    /// Enforce that the iterator only iterates over the same
    /// prefix as the seek.
    /// This option is effective only for prefix seeks, i.e. prefix_extractor is
    /// non-null for the column family and total_order_seek is false.  Unlike
    /// iterate_upper_bound, prefix_same_as_start only works within a prefix
    /// but in both directions.
    ///
    /// Default: false
    pub fn set_prefix_same_as_start(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_prefix_same_as_start(self.inner, c_uchar::from(v));
        }
    }

    /// Enable a total order seek regardless of index format (e.g. hash index)
    /// used in the table. Some table format (e.g. plain table) may not support
    /// this option.
    ///
    /// If true when calling Get(), we also skip prefix bloom when reading from
    /// block based table. It provides a way to read existing data after
    /// changing implementation of prefix extractor.
    pub fn set_total_order_seek(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_total_order_seek(self.inner, c_uchar::from(v));
        }
    }

    /// Sets a threshold for the number of keys that can be skipped
    /// before failing an iterator seek as incomplete. The default value of 0 should be used to
    /// never fail a request as incomplete, even on skipping too many keys.
    ///
    /// Default: 0
    pub fn set_max_skippable_internal_keys(&mut self, num: u64) {
        unsafe {
            ffi::rocksdb_readoptions_set_max_skippable_internal_keys(self.inner, num);
        }
    }

    /// If true, when PurgeObsoleteFile is called in CleanupIteratorState, we schedule a background job
    /// in the flush job queue and delete obsolete files in background.
    ///
    /// Default: false
    pub fn set_background_purge_on_iterator_cleanup(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_background_purge_on_iterator_cleanup(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// If true, keys deleted using the DeleteRange() API will be visible to
    /// readers until they are naturally deleted during compaction.
    ///
    /// Default: false
    #[deprecated(
        note = "deprecated in RocksDB 10.2.1: no performance impact if DeleteRange is not used"
    )]
    pub fn set_ignore_range_deletions(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_ignore_range_deletions(self.inner, c_uchar::from(v));
        }
    }

    /// If true, all data read from underlying storage will be
    /// verified against corresponding checksums.
    ///
    /// Default: true
    pub fn set_verify_checksums(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_verify_checksums(self.inner, c_uchar::from(v));
        }
    }

    /// If non-zero, an iterator will create a new table reader which
    /// performs reads of the given size. Using a large size (> 2MB) can
    /// improve the performance of forward iteration on spinning disks.
    /// Default: 0
    ///
    /// ```
    /// use rocksdb::{ReadOptions};
    ///
    /// let mut opts = ReadOptions::default();
    /// opts.set_readahead_size(4_194_304); // 4mb
    /// ```
    pub fn set_readahead_size(&mut self, v: usize) {
        unsafe {
            ffi::rocksdb_readoptions_set_readahead_size(self.inner, v as size_t);
        }
    }

    /// If auto_readahead_size is set to true, it will auto tune the readahead_size
    /// during scans internally.
    /// For this feature to be enabled, iterate_upper_bound must also be specified.
    ///
    /// NOTE: - Recommended for forward Scans only.
    ///       - If there is a backward scans, this option will be
    ///         disabled internally and won't be enabled again if the forward scan
    ///         is issued again.
    ///
    /// Default: true
    pub fn set_auto_readahead_size(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_auto_readahead_size(self.inner, c_uchar::from(v));
        }
    }

    /// If true, create a tailing iterator. Note that tailing iterators
    /// only support moving in the forward direction. Iterating in reverse
    /// or seek_to_last are not supported.
    pub fn set_tailing(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_tailing(self.inner, c_uchar::from(v));
        }
    }

    /// Specifies the value of "pin_data". If true, it keeps the blocks
    /// loaded by the iterator pinned in memory as long as the iterator is not deleted,
    /// If used when reading from tables created with
    /// BlockBasedTableOptions::use_delta_encoding = false,
    /// Iterator's property "rocksdb.iterator.is-key-pinned" is guaranteed to
    /// return 1.
    ///
    /// Default: false
    pub fn set_pin_data(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_pin_data(self.inner, c_uchar::from(v));
        }
    }

    /// Asynchronously prefetch some data.
    ///
    /// Used for sequential reads and internal automatic prefetching.
    ///
    /// Default: `false`
    pub fn set_async_io(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_readoptions_set_async_io(self.inner, c_uchar::from(v));
        }
    }

    /// Timestamp of operation. Read should return the latest data visible to the
    /// specified timestamp. All timestamps of the same database must be of the
    /// same length and format. The user is responsible for providing a customized
    /// compare function via Comparator to order <key, timestamp> tuples.
    /// For iterator, iter_start_ts is the lower bound (older) and timestamp
    /// serves as the upper bound. Versions of the same record that fall in
    /// the timestamp range will be returned. If iter_start_ts is nullptr,
    /// only the most recent version visible to timestamp is returned.
    /// The user-specified timestamp feature is still under active development,
    /// and the API is subject to change.
    pub fn set_timestamp<S: Into<Vec<u8>>>(&mut self, ts: S) {
        self.set_timestamp_impl(Some(ts.into()));
    }

    fn set_timestamp_impl(&mut self, ts: Option<Vec<u8>>) {
        let (ptr, len) = if let Some(ref ts) = ts {
            (ts.as_ptr() as *const c_char, ts.len())
        } else if self.timestamp.is_some() {
            // The stored timestamp is a `Some` but we're updating it to a `None`.
            // This means to cancel a previously set timestamp.
            // To do this, use a null pointer and zero length.
            (std::ptr::null(), 0)
        } else {
            return;
        };
        self.timestamp = ts;
        unsafe {
            ffi::rocksdb_readoptions_set_timestamp(self.inner, ptr, len);
        }
    }

    /// See `set_timestamp`
    pub fn set_iter_start_ts<S: Into<Vec<u8>>>(&mut self, ts: S) {
        self.set_iter_start_ts_impl(Some(ts.into()));
    }

    fn set_iter_start_ts_impl(&mut self, ts: Option<Vec<u8>>) {
        let (ptr, len) = if let Some(ref ts) = ts {
            (ts.as_ptr() as *const c_char, ts.len())
        } else if self.timestamp.is_some() {
            (std::ptr::null(), 0)
        } else {
            return;
        };
        self.iter_start_ts = ts;
        unsafe {
            ffi::rocksdb_readoptions_set_iter_start_ts(self.inner, ptr, len);
        }
    }
}

impl Default for ReadOptions {
    fn default() -> Self {
        unsafe {
            Self {
                inner: ffi::rocksdb_readoptions_create(),
                timestamp: None,
                iter_start_ts: None,
                iterate_upper_bound: None,
                iterate_lower_bound: None,
            }
        }
    }
}

impl IngestExternalFileOptions {
    /// Can be set to true to move the files instead of copying them.
    pub fn set_move_files(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_set_move_files(self.inner, c_uchar::from(v));
        }
    }

    /// If set to false, an ingested file keys could appear in existing snapshots
    /// that where created before the file was ingested.
    pub fn set_snapshot_consistency(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_set_snapshot_consistency(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// If set to false, IngestExternalFile() will fail if the file key range
    /// overlaps with existing keys or tombstones in the DB.
    pub fn set_allow_global_seqno(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_set_allow_global_seqno(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// If set to false and the file key range overlaps with the memtable key range
    /// (memtable flush required), IngestExternalFile will fail.
    pub fn set_allow_blocking_flush(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_set_allow_blocking_flush(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// Set to true if you would like duplicate keys in the file being ingested
    /// to be skipped rather than overwriting existing data under that key.
    /// Usecase: back-fill of some historical data in the database without
    /// over-writing existing newer version of data.
    /// This option could only be used if the DB has been running
    /// with allow_ingest_behind=true since the dawn of time.
    /// All files will be ingested at the bottommost level with seqno=0.
    pub fn set_ingest_behind(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_ingestexternalfileoptions_set_ingest_behind(self.inner, c_uchar::from(v));
        }
    }
}

impl Default for IngestExternalFileOptions {
    fn default() -> Self {
        unsafe {
            Self {
                inner: ffi::rocksdb_ingestexternalfileoptions_create(),
            }
        }
    }
}

/// Used by BlockBasedOptions::set_index_type.
pub enum BlockBasedIndexType {
    /// A space efficient index block that is optimized for
    /// binary-search-based index.
    BinarySearch,

    /// The hash index, if enabled, will perform a hash lookup if
    /// a prefix extractor has been provided through Options::set_prefix_extractor.
    HashSearch,

    /// A two-level index implementation. Both levels are binary search indexes.
    TwoLevelIndexSearch,
}

/// Used by BlockBasedOptions::set_data_block_index_type.
#[repr(C)]
pub enum DataBlockIndexType {
    /// Use binary search when performing point lookup for keys in data blocks.
    /// This is the default.
    BinarySearch = 0,

    /// Appends a compact hash table to the end of the data block for efficient indexing. Backwards
    /// compatible with databases created without this feature. Once turned on, existing data will
    /// be gradually converted to the hash index format.
    BinaryAndHash = 1,
}

/// Used by BlockBasedOptions for setting metadata cache pinning tiers.
/// Controls how metadata blocks (index, filter, etc.) are pinned in block cache.
#[repr(C)]
pub enum BlockBasedTablePinningTier {
    /// Use fallback pinning tier (context-dependent)
    Fallback = ffi::rocksdb_block_based_k_fallback_pinning_tier as isize,
    /// No pinning - blocks can be evicted at any time
    None = ffi::rocksdb_block_based_k_none_pinning_tier as isize,
    /// Pin blocks for flushed files and similar scenarios
    FlushAndSimilar = ffi::rocksdb_block_based_k_flush_and_similar_pinning_tier as isize,
    /// Pin all blocks (highest priority)
    All = ffi::rocksdb_block_based_k_all_pinning_tier as isize,
}

/// Defines the underlying memtable implementation.
/// See official [wiki](https://github.com/facebook/rocksdb/wiki/MemTable) for more information.
pub enum MemtableFactory {
    Vector,
    HashSkipList {
        bucket_count: usize,
        height: i32,
        branching_factor: i32,
    },
    HashLinkList {
        bucket_count: usize,
    },
}

/// Used by BlockBasedOptions::set_checksum_type.
pub enum ChecksumType {
    NoChecksum = 0,
    CRC32c = 1,
    XXHash = 2,
    XXHash64 = 3,
    XXH3 = 4, // Supported since RocksDB 6.27
}

/// Used in [`PlainTableFactoryOptions`].
#[derive(Debug, Copy, Clone, PartialEq, Eq, Default)]
pub enum KeyEncodingType {
    /// Always write full keys.
    #[default]
    Plain = 0,
    /// Find opportunities to write the same prefix for multiple rows.
    Prefix = 1,
}

/// Used with DBOptions::set_plain_table_factory.
/// See official [wiki](https://github.com/facebook/rocksdb/wiki/PlainTable-Format) for more
/// information.
///
/// Defaults:
///  user_key_length: 0 (variable length)
///  bloom_bits_per_key: 10
///  hash_table_ratio: 0.75
///  index_sparseness: 16
///  huge_page_tlb_size: 0
///  encoding_type: KeyEncodingType::Plain
///  full_scan_mode: false
///  store_index_in_file: false
pub struct PlainTableFactoryOptions {
    pub user_key_length: u32,
    pub bloom_bits_per_key: i32,
    pub hash_table_ratio: f64,
    pub index_sparseness: usize,
    pub huge_page_tlb_size: usize,
    pub encoding_type: KeyEncodingType,
    pub full_scan_mode: bool,
    pub store_index_in_file: bool,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
pub enum DBCompressionType {
    None = ffi::rocksdb_no_compression as isize,
    Snappy = ffi::rocksdb_snappy_compression as isize,
    Zlib = ffi::rocksdb_zlib_compression as isize,
    Bz2 = ffi::rocksdb_bz2_compression as isize,
    Lz4 = ffi::rocksdb_lz4_compression as isize,
    Lz4hc = ffi::rocksdb_lz4hc_compression as isize,
    Zstd = ffi::rocksdb_zstd_compression as isize,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
pub enum DBCompactionStyle {
    Level = ffi::rocksdb_level_compaction as isize,
    Universal = ffi::rocksdb_universal_compaction as isize,
    Fifo = ffi::rocksdb_fifo_compaction as isize,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
pub enum DBRecoveryMode {
    TolerateCorruptedTailRecords = ffi::rocksdb_tolerate_corrupted_tail_records_recovery as isize,
    AbsoluteConsistency = ffi::rocksdb_absolute_consistency_recovery as isize,
    PointInTime = ffi::rocksdb_point_in_time_recovery as isize,
    SkipAnyCorruptedRecord = ffi::rocksdb_skip_any_corrupted_records_recovery as isize,
}

pub struct FifoCompactOptions {
    pub(crate) inner: *mut ffi::rocksdb_fifo_compaction_options_t,
}

impl Default for FifoCompactOptions {
    fn default() -> Self {
        let opts = unsafe { ffi::rocksdb_fifo_compaction_options_create() };
        assert!(
            !opts.is_null(),
            "Could not create RocksDB Fifo Compaction Options"
        );

        Self { inner: opts }
    }
}

impl Drop for FifoCompactOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_fifo_compaction_options_destroy(self.inner);
        }
    }
}

impl FifoCompactOptions {
    /// Sets the max table file size.
    ///
    /// Once the total sum of table files reaches this, we will delete the oldest
    /// table file
    ///
    /// Default: 1GB
    pub fn set_max_table_files_size(&mut self, nbytes: u64) {
        unsafe {
            ffi::rocksdb_fifo_compaction_options_set_max_table_files_size(self.inner, nbytes);
        }
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
pub enum UniversalCompactionStopStyle {
    Similar = ffi::rocksdb_similar_size_compaction_stop_style as isize,
    Total = ffi::rocksdb_total_size_compaction_stop_style as isize,
}

pub struct UniversalCompactOptions {
    pub(crate) inner: *mut ffi::rocksdb_universal_compaction_options_t,
}

impl Default for UniversalCompactOptions {
    fn default() -> Self {
        let opts = unsafe { ffi::rocksdb_universal_compaction_options_create() };
        assert!(
            !opts.is_null(),
            "Could not create RocksDB Universal Compaction Options"
        );

        Self { inner: opts }
    }
}

impl Drop for UniversalCompactOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_destroy(self.inner);
        }
    }
}

impl UniversalCompactOptions {
    /// Sets the percentage flexibility while comparing file size.
    /// If the candidate file(s) size is 1% smaller than the next file's size,
    /// then include next file into this candidate set.
    ///
    /// Default: 1
    pub fn set_size_ratio(&mut self, ratio: c_int) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_size_ratio(self.inner, ratio);
        }
    }

    /// Sets the minimum number of files in a single compaction run.
    ///
    /// Default: 2
    pub fn set_min_merge_width(&mut self, num: c_int) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_min_merge_width(self.inner, num);
        }
    }

    /// Sets the maximum number of files in a single compaction run.
    ///
    /// Default: UINT_MAX
    pub fn set_max_merge_width(&mut self, num: c_int) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_max_merge_width(self.inner, num);
        }
    }

    /// sets the size amplification.
    ///
    /// It is defined as the amount (in percentage) of
    /// additional storage needed to store a single byte of data in the database.
    /// For example, a size amplification of 2% means that a database that
    /// contains 100 bytes of user-data may occupy upto 102 bytes of
    /// physical storage. By this definition, a fully compacted database has
    /// a size amplification of 0%. Rocksdb uses the following heuristic
    /// to calculate size amplification: it assumes that all files excluding
    /// the earliest file contribute to the size amplification.
    ///
    /// Default: 200, which means that a 100 byte database could require upto 300 bytes of storage.
    pub fn set_max_size_amplification_percent(&mut self, v: c_int) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_max_size_amplification_percent(
                self.inner, v,
            );
        }
    }

    /// Sets the percentage of compression size.
    ///
    /// If this option is set to be -1, all the output files
    /// will follow compression type specified.
    ///
    /// If this option is not negative, we will try to make sure compressed
    /// size is just above this value. In normal cases, at least this percentage
    /// of data will be compressed.
    /// When we are compacting to a new file, here is the criteria whether
    /// it needs to be compressed: assuming here are the list of files sorted
    /// by generation time:
    ///    A1...An B1...Bm C1...Ct
    /// where A1 is the newest and Ct is the oldest, and we are going to compact
    /// B1...Bm, we calculate the total size of all the files as total_size, as
    /// well as  the total size of C1...Ct as total_C, the compaction output file
    /// will be compressed iff
    ///   total_C / total_size < this percentage
    ///
    /// Default: -1
    pub fn set_compression_size_percent(&mut self, v: c_int) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_compression_size_percent(self.inner, v);
        }
    }

    /// Sets the algorithm used to stop picking files into a single compaction run.
    ///
    /// Default: ::Total
    pub fn set_stop_style(&mut self, style: UniversalCompactionStopStyle) {
        unsafe {
            ffi::rocksdb_universal_compaction_options_set_stop_style(self.inner, style as c_int);
        }
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
#[repr(u8)]
pub enum BottommostLevelCompaction {
    /// Skip bottommost level compaction
    Skip = 0,
    /// Only compact bottommost level if there is a compaction filter
    /// This is the default option
    IfHaveCompactionFilter,
    /// Always compact bottommost level
    Force,
    /// Always compact bottommost level but in bottommost level avoid
    /// double-compacting files created in the same compaction
    ForceOptimized,
}

pub struct CompactOptions {
    pub(crate) inner: *mut ffi::rocksdb_compactoptions_t,
    full_history_ts_low: Option<Vec<u8>>,
}

impl Default for CompactOptions {
    fn default() -> Self {
        let opts = unsafe { ffi::rocksdb_compactoptions_create() };
        assert!(!opts.is_null(), "Could not create RocksDB Compact Options");

        Self {
            inner: opts,
            full_history_ts_low: None,
        }
    }
}

impl Drop for CompactOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_compactoptions_destroy(self.inner);
        }
    }
}

impl CompactOptions {
    /// If more than one thread calls manual compaction,
    /// only one will actually schedule it while the other threads will simply wait
    /// for the scheduled manual compaction to complete. If exclusive_manual_compaction
    /// is set to true, the call will disable scheduling of automatic compaction jobs
    /// and wait for existing automatic compaction jobs to finish.
    pub fn set_exclusive_manual_compaction(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_compactoptions_set_exclusive_manual_compaction(
                self.inner,
                c_uchar::from(v),
            );
        }
    }

    /// Sets bottommost level compaction.
    pub fn set_bottommost_level_compaction(&mut self, lvl: BottommostLevelCompaction) {
        unsafe {
            ffi::rocksdb_compactoptions_set_bottommost_level_compaction(self.inner, lvl as c_uchar);
        }
    }

    /// If true, compacted files will be moved to the minimum level capable
    /// of holding the data or given level (specified non-negative target_level).
    pub fn set_change_level(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_compactoptions_set_change_level(self.inner, c_uchar::from(v));
        }
    }

    /// If change_level is true and target_level have non-negative value, compacted
    /// files will be moved to target_level.
    pub fn set_target_level(&mut self, lvl: c_int) {
        unsafe {
            ffi::rocksdb_compactoptions_set_target_level(self.inner, lvl);
        }
    }

    /// Set user-defined timestamp low bound, the data with older timestamp than
    /// low bound maybe GCed by compaction. Default: nullptr
    pub fn set_full_history_ts_low<S: Into<Vec<u8>>>(&mut self, ts: S) {
        self.set_full_history_ts_low_impl(Some(ts.into()));
    }

    fn set_full_history_ts_low_impl(&mut self, ts: Option<Vec<u8>>) {
        let (ptr, len) = if let Some(ref ts) = ts {
            (ts.as_ptr() as *mut c_char, ts.len())
        } else if self.full_history_ts_low.is_some() {
            (std::ptr::null::<Vec<u8>>() as *mut c_char, 0)
        } else {
            return;
        };
        self.full_history_ts_low = ts;
        unsafe {
            ffi::rocksdb_compactoptions_set_full_history_ts_low(self.inner, ptr, len);
        }
    }
}

pub struct WaitForCompactOptions {
    pub(crate) inner: *mut ffi::rocksdb_wait_for_compact_options_t,
}

impl Default for WaitForCompactOptions {
    fn default() -> Self {
        let opts = unsafe { ffi::rocksdb_wait_for_compact_options_create() };
        assert!(
            !opts.is_null(),
            "Could not create RocksDB Wait For Compact Options"
        );

        Self { inner: opts }
    }
}

impl Drop for WaitForCompactOptions {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_wait_for_compact_options_destroy(self.inner);
        }
    }
}

impl WaitForCompactOptions {
    /// If true, abort waiting if background jobs are paused. If false,
    /// ContinueBackgroundWork() must be called to resume the background jobs.
    /// Otherwise, jobs that were queued, but not scheduled yet may never finish
    /// and WaitForCompact() may wait indefinitely (if timeout is set, it will
    /// abort after the timeout).
    ///
    /// Default: false
    pub fn set_abort_on_pause(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_wait_for_compact_options_set_abort_on_pause(self.inner, c_uchar::from(v));
        }
    }

    /// If true, flush all column families before starting to wait.
    ///
    /// Default: false
    pub fn set_flush(&mut self, v: bool) {
        unsafe {
            ffi::rocksdb_wait_for_compact_options_set_flush(self.inner, c_uchar::from(v));
        }
    }

    /// Timeout in microseconds for waiting for compaction to complete.
    /// when timeout == 0, WaitForCompact() will wait as long as there's background
    /// work to finish.
    ///
    /// Default: 0
    pub fn set_timeout(&mut self, microseconds: u64) {
        unsafe {
            ffi::rocksdb_wait_for_compact_options_set_timeout(self.inner, microseconds);
        }
    }
}

/// Represents a path where sst files can be put into
pub struct DBPath {
    pub(crate) inner: *mut ffi::rocksdb_dbpath_t,
}

impl DBPath {
    /// Create a new path
    pub fn new<P: AsRef<Path>>(path: P, target_size: u64) -> Result<Self, Error> {
        let p = to_cpath(path.as_ref()).unwrap();
        let dbpath = unsafe { ffi::rocksdb_dbpath_create(p.as_ptr(), target_size) };
        if dbpath.is_null() {
            Err(Error::new(format!(
                "Could not create path for storing sst files at location: {}",
                path.as_ref().display()
            )))
        } else {
            Ok(DBPath { inner: dbpath })
        }
    }
}

impl Drop for DBPath {
    fn drop(&mut self) {
        unsafe {
            ffi::rocksdb_dbpath_destroy(self.inner);
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::db_options::WriteBufferManager;
    use crate::{Cache, CompactionPri, MemtableFactory, Options};

    #[test]
    fn test_enable_statistics() {
        let mut opts = Options::default();
        opts.enable_statistics();
        opts.set_stats_dump_period_sec(60);
        assert!(opts.get_statistics().is_some());

        let opts = Options::default();
        assert!(opts.get_statistics().is_none());
    }

    #[test]
    fn test_set_memtable_factory() {
        let mut opts = Options::default();
        opts.set_memtable_factory(MemtableFactory::Vector);
        opts.set_memtable_factory(MemtableFactory::HashLinkList { bucket_count: 100 });
        opts.set_memtable_factory(MemtableFactory::HashSkipList {
            bucket_count: 100,
            height: 4,
            branching_factor: 4,
        });
    }

    #[test]
    fn test_use_fsync() {
        let mut opts = Options::default();
        assert!(!opts.get_use_fsync());
        opts.set_use_fsync(true);
        assert!(opts.get_use_fsync());
    }

    #[test]
    fn test_set_stats_persist_period_sec() {
        let mut opts = Options::default();
        opts.enable_statistics();
        opts.set_stats_persist_period_sec(5);
        assert!(opts.get_statistics().is_some());

        let opts = Options::default();
        assert!(opts.get_statistics().is_none());
    }

    #[test]
    fn test_set_write_buffer_manager() {
        let mut opts = Options::default();
        let lrucache = Cache::new_lru_cache(100);
        let write_buffer_manager =
            WriteBufferManager::new_write_buffer_manager_with_cache(100, false, lrucache);
        assert_eq!(write_buffer_manager.get_buffer_size(), 100);
        assert_eq!(write_buffer_manager.get_usage(), 0);
        assert!(write_buffer_manager.enabled());

        opts.set_write_buffer_manager(&write_buffer_manager);
        drop(opts);

        // WriteBufferManager outlives options
        assert!(write_buffer_manager.enabled());
    }

    #[test]
    fn compaction_pri() {
        let mut opts = Options::default();
        opts.set_compaction_pri(CompactionPri::RoundRobin);
        opts.create_if_missing(true);
        let tmp = tempfile::tempdir().unwrap();
        let _db = crate::DB::open(&opts, tmp.path()).unwrap();

        let options = std::fs::read_dir(tmp.path())
            .unwrap()
            .find_map(|x| {
                let x = x.ok()?;
                x.file_name()
                    .into_string()
                    .unwrap()
                    .contains("OPTIONS")
                    .then_some(x.path())
            })
            .map(std::fs::read_to_string)
            .unwrap()
            .unwrap();

        assert!(options.contains("compaction_pri=kRoundRobin"));
    }
}