rust_rocksdb/

db.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::cell::RefCell;
use std::collections::{BTreeMap, HashMap};
use std::ffi::{CStr, CString};
use std::fmt;
use std::fs;
use std::iter;
use std::path::Path;
use std::path::PathBuf;
use std::ptr;
use std::slice;
use std::str;
use std::sync::Arc;
use std::time::Duration;

use crate::column_family::ColumnFamilyTtl;
use crate::ffi_util::CSlice;
use crate::{
    ColumnFamily, ColumnFamilyDescriptor, CompactOptions, DBIteratorWithThreadMode,
    DBPinnableSlice, DBRawIteratorWithThreadMode, DBWALIterator, DEFAULT_COLUMN_FAMILY_NAME,
    Direction, Error, FlushOptions, IngestExternalFileOptions, IteratorMode, Options, ReadOptions,
    SnapshotWithThreadMode, WaitForCompactOptions, WriteBatch, WriteBatchWithIndex, WriteOptions,
    column_family::{AsColumnFamilyRef, BoundColumnFamily, UnboundColumnFamily},
    db_options::{ImportColumnFamilyOptions, OptionsMustOutliveDB},
    ffi,
    ffi_util::{
        CStrLike, convert_rocksdb_error, from_cstr_and_free, from_cstr_without_free,
        opt_bytes_to_ptr, raw_data, to_cpath,
    },
};
use rust_librocksdb_sys::{
    rocksdb_livefile_destroy, rocksdb_livefile_t, rocksdb_livefiles_destroy, rocksdb_livefiles_t,
};

use libc::{self, c_char, c_int, c_uchar, c_void, size_t};
use parking_lot::RwLock;

// Default options are kept per-thread to avoid re-allocating on every call while
// also preventing cross-thread sharing. Some RocksDB option wrappers hold
// pointers into internal buffers and are not safe to share across threads.
// Using thread_local allows cheap reuse in the common "default options" path
// without synchronization overhead. Callers who need non-defaults must pass
// explicit options.
thread_local! { static DEFAULT_READ_OPTS: ReadOptions = ReadOptions::default(); }
thread_local! { static DEFAULT_WRITE_OPTS: WriteOptions = WriteOptions::default(); }
thread_local! { static DEFAULT_FLUSH_OPTS: FlushOptions = FlushOptions::default(); }
// Thread-local ReadOptions for hot prefix probes; preconfigured for prefix scans.
thread_local! { static PREFIX_READ_OPTS: RefCell<ReadOptions> = RefCell::new({ let mut o = ReadOptions::default(); o.set_prefix_same_as_start(true); o }); }

/// A range of keys, `start_key` is included, but not `end_key`.
///
/// You should make sure `end_key` is not less than `start_key`.
pub struct Range<'a> {
    start_key: &'a [u8],
    end_key: &'a [u8],
}

impl<'a> Range<'a> {
    pub fn new(start_key: &'a [u8], end_key: &'a [u8]) -> Range<'a> {
        Range { start_key, end_key }
    }
}

/// Result of a [`get_into_buffer`](DBCommon::get_into_buffer) operation.
///
/// This enum represents the outcome of attempting to read a value directly
/// into a caller-provided buffer, avoiding memory allocation. This is the most
/// efficient way to read values when you have a pre-allocated buffer available.
///
/// # Performance
///
/// Using `get_into_buffer` with a reusable buffer can significantly reduce
/// allocation overhead in hot paths compared to [`get`](DBCommon::get) or even
/// [`get_pinned`](DBCommon::get_pinned):
///
/// - [`get`](DBCommon::get): Allocates a new `Vec<u8>` for each call
/// - [`get_pinned`](DBCommon::get_pinned): Pins memory in RocksDB's block cache
/// - `get_into_buffer`: Zero allocation when buffer is large enough
///
/// # Example
///
/// ```
/// use rust_rocksdb::{DB, GetIntoBufferResult};
///
/// # let tempdir = tempfile::Builder::new().prefix("ex").tempdir().unwrap();
/// let db = DB::open_default(tempdir.path()).unwrap();
/// db.put(b"key", b"value").unwrap();
///
/// let mut buffer = [0u8; 1024];
/// match db.get_into_buffer(b"key", &mut buffer).unwrap() {
///     GetIntoBufferResult::Found(len) => {
///         println!("Value: {:?}", &buffer[..len]);
///     }
///     GetIntoBufferResult::NotFound => {
///         println!("Key not found");
///     }
///     GetIntoBufferResult::BufferTooSmall(needed) => {
///         println!("Need a buffer of at least {} bytes", needed);
///     }
/// }
/// ```
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum GetIntoBufferResult {
    /// The key was not found in the database.
    NotFound,
    /// The value was found and successfully copied into the buffer.
    /// The `usize` contains the actual size of the value (number of bytes written).
    Found(usize),
    /// The value was found but the provided buffer was too small to hold it.
    /// The `usize` contains the actual size of the value, allowing the caller
    /// to allocate a larger buffer and retry.
    ///
    /// Note: When this variant is returned, no data is written to the buffer.
    BufferTooSmall(usize),
}

impl GetIntoBufferResult {
    /// Returns `true` if the key was found (regardless of buffer size).
    #[inline]
    pub fn is_found(&self) -> bool {
        matches!(self, Self::Found(_) | Self::BufferTooSmall(_))
    }

    /// Returns `true` if the key was not found.
    #[inline]
    pub fn is_not_found(&self) -> bool {
        matches!(self, Self::NotFound)
    }

    /// Returns the value size if the key was found, `None` otherwise.
    #[inline]
    pub fn value_size(&self) -> Option<usize> {
        match self {
            Self::Found(size) | Self::BufferTooSmall(size) => Some(*size),
            Self::NotFound => None,
        }
    }
}

/// A reusable prefix probe that avoids per-call iterator creation/destruction.
///
/// Use this when performing many prefix existence checks in a tight loop.
pub struct PrefixProber<'a, D: DBAccess> {
    raw: DBRawIteratorWithThreadMode<'a, D>,
}

impl<D: DBAccess> PrefixProber<'_, D> {
    /// Returns true if any key exists with the given prefix.
    /// This performs a seek to the prefix and checks the current key.
    pub fn exists(&mut self, prefix: &[u8]) -> Result<bool, Error> {
        self.raw.seek(prefix);
        if self.raw.valid()
            && let Some(k) = self.raw.key()
        {
            return Ok(k.starts_with(prefix));
        }
        self.raw.status()?;
        Ok(false)
    }
}

/// Marker trait to specify single or multi threaded column family alternations for
/// [`DBWithThreadMode<T>`]
///
/// This arrangement makes differences in self mutability and return type in
/// some of `DBWithThreadMode` methods.
///
/// While being a marker trait to be generic over `DBWithThreadMode`, this trait
/// also has a minimum set of not-encapsulated internal methods between
/// [`SingleThreaded`] and [`MultiThreaded`].  These methods aren't expected to be
/// called and defined externally.
pub trait ThreadMode {
    /// Internal implementation for storing column family handles
    fn new_cf_map_internal(
        cf_map: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
    ) -> Self;
    /// Internal implementation for dropping column family handles
    fn drop_all_cfs_internal(&mut self);
}

/// Actual marker type for the marker trait `ThreadMode`, which holds
/// a collection of column families without synchronization primitive, providing
/// no overhead for the single-threaded column family alternations. The other
/// mode is [`MultiThreaded`].
///
/// See [`DB`] for more details, including performance implications for each mode
pub struct SingleThreaded {
    pub(crate) cfs: HashMap<String, ColumnFamily>,
}

/// Actual marker type for the marker trait `ThreadMode`, which holds
/// a collection of column families wrapped in a RwLock to be mutated
/// concurrently. The other mode is [`SingleThreaded`].
///
/// See [`DB`] for more details, including performance implications for each mode
pub struct MultiThreaded {
    pub(crate) cfs: RwLock<HashMap<String, Arc<UnboundColumnFamily>>>,
}

impl ThreadMode for SingleThreaded {
    fn new_cf_map_internal(
        cfs: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
    ) -> Self {
        Self {
            cfs: cfs
                .into_iter()
                .map(|(n, c)| (n, ColumnFamily { inner: c }))
                .collect(),
        }
    }

    fn drop_all_cfs_internal(&mut self) {
        // Cause all ColumnFamily objects to be Drop::drop()-ed.
        self.cfs.clear();
    }
}

impl ThreadMode for MultiThreaded {
    fn new_cf_map_internal(
        cfs: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
    ) -> Self {
        Self {
            cfs: RwLock::new(
                cfs.into_iter()
                    .map(|(n, c)| (n, Arc::new(UnboundColumnFamily { inner: c })))
                    .collect(),
            ),
        }
    }

    fn drop_all_cfs_internal(&mut self) {
        // Cause all UnboundColumnFamily objects to be Drop::drop()-ed.
        self.cfs.write().clear();
    }
}

/// Get underlying `rocksdb_t`.
pub trait DBInner {
    fn inner(&self) -> *mut ffi::rocksdb_t;
}

/// A helper type to implement some common methods for [`DBWithThreadMode`]
/// and [`OptimisticTransactionDB`].
///
/// [`OptimisticTransactionDB`]: crate::OptimisticTransactionDB
///
/// When using [`SingleThreaded`] mode, `create_cf` requires `&mut self`,
/// preventing multiple immutable references from calling it concurrently:
///
/// ```compile_fail,E0596
/// use rust_rocksdb::{DBWithThreadMode, Options, SingleThreaded};
///
/// let db = DBWithThreadMode::<SingleThreaded>::open_default("/path/to/dummy").unwrap();
/// let db_ref1 = &db;
/// let db_ref2 = &db;
/// let opts = Options::default();
/// db_ref1.create_cf("cf1", &opts).unwrap();
/// db_ref2.create_cf("cf2", &opts).unwrap();
/// ```
///
/// [`SingleThreaded`]: crate::SingleThreaded
pub struct DBCommon<T: ThreadMode, D: DBInner> {
    pub(crate) inner: D,
    cfs: T, // Column families are held differently depending on thread mode
    path: PathBuf,
    _outlive: Vec<OptionsMustOutliveDB>,
}

/// Minimal set of DB-related methods, intended to be generic over
/// `DBWithThreadMode<T>`. Mainly used internally
pub trait DBAccess {
    unsafe fn create_snapshot(&self) -> *const ffi::rocksdb_snapshot_t;

    unsafe fn release_snapshot(&self, snapshot: *const ffi::rocksdb_snapshot_t);

    unsafe fn create_iterator(&self, readopts: &ReadOptions) -> *mut ffi::rocksdb_iterator_t;

    unsafe fn create_iterator_cf(
        &self,
        cf_handle: *mut ffi::rocksdb_column_family_handle_t,
        readopts: &ReadOptions,
    ) -> *mut ffi::rocksdb_iterator_t;

    fn get_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error>;

    fn get_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error>;

    fn get_pinned_opt<K: AsRef<[u8]>>(
        &'_ self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error>;

    fn get_pinned_cf_opt<K: AsRef<[u8]>>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error>;

    fn multi_get_opt<K, I>(
        &self,
        keys: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = K>;

    fn multi_get_cf_opt<'b, K, I, W>(
        &self,
        keys_cf: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = (&'b W, K)>,
        W: AsColumnFamilyRef + 'b;
}

impl<T: ThreadMode, D: DBInner> DBAccess for DBCommon<T, D> {
    unsafe fn create_snapshot(&self) -> *const ffi::rocksdb_snapshot_t {
        unsafe { ffi::rocksdb_create_snapshot(self.inner.inner()) }
    }

    unsafe fn release_snapshot(&self, snapshot: *const ffi::rocksdb_snapshot_t) {
        unsafe {
            ffi::rocksdb_release_snapshot(self.inner.inner(), snapshot);
        }
    }

    unsafe fn create_iterator(&self, readopts: &ReadOptions) -> *mut ffi::rocksdb_iterator_t {
        unsafe { ffi::rocksdb_create_iterator(self.inner.inner(), readopts.inner) }
    }

    unsafe fn create_iterator_cf(
        &self,
        cf_handle: *mut ffi::rocksdb_column_family_handle_t,
        readopts: &ReadOptions,
    ) -> *mut ffi::rocksdb_iterator_t {
        unsafe { ffi::rocksdb_create_iterator_cf(self.inner.inner(), readopts.inner, cf_handle) }
    }

    fn get_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error> {
        self.get_opt(key, readopts)
    }

    fn get_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error> {
        self.get_cf_opt(cf, key, readopts)
    }

    fn get_pinned_opt<K: AsRef<[u8]>>(
        &'_ self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        self.get_pinned_opt(key, readopts)
    }

    fn get_pinned_cf_opt<K: AsRef<[u8]>>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        self.get_pinned_cf_opt(cf, key, readopts)
    }

    fn multi_get_opt<K, Iter>(
        &self,
        keys: Iter,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        Iter: IntoIterator<Item = K>,
    {
        self.multi_get_opt(keys, readopts)
    }

    fn multi_get_cf_opt<'b, K, Iter, W>(
        &self,
        keys_cf: Iter,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        Iter: IntoIterator<Item = (&'b W, K)>,
        W: AsColumnFamilyRef + 'b,
    {
        self.multi_get_cf_opt(keys_cf, readopts)
    }
}

pub struct DBWithThreadModeInner {
    inner: *mut ffi::rocksdb_t,
}

impl DBInner for DBWithThreadModeInner {
    fn inner(&self) -> *mut ffi::rocksdb_t {
        self.inner
    }
}

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

/// A type alias to RocksDB database.
///
/// See crate level documentation for a simple usage example.
/// See [`DBCommon`] for full list of methods.
pub type DBWithThreadMode<T> = DBCommon<T, DBWithThreadModeInner>;

/// A type alias to DB instance type with the single-threaded column family
/// creations/deletions
///
/// # Compatibility and multi-threaded mode
///
/// Previously, [`DB`] was defined as a direct `struct`. Now, it's type-aliased for
/// compatibility. Use `DBCommon<MultiThreaded>` for multi-threaded
/// column family alternations.
///
/// # Limited performance implication for single-threaded mode
///
/// Even with [`SingleThreaded`], almost all of RocksDB operations is
/// multi-threaded unless the underlying RocksDB instance is
/// specifically configured otherwise. `SingleThreaded` only forces
/// serialization of column family alternations by requiring `&mut self` of DB
/// instance due to its wrapper implementation details.
///
/// # Multi-threaded mode
///
/// [`MultiThreaded`] can be appropriate for the situation of multi-threaded
/// workload including multi-threaded column family alternations, costing the
/// RwLock overhead inside `DB`.
#[cfg(not(feature = "multi-threaded-cf"))]
pub type DB = DBWithThreadMode<SingleThreaded>;

#[cfg(feature = "multi-threaded-cf")]
pub type DB = DBWithThreadMode<MultiThreaded>;

// 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<T: ThreadMode + Send, I: DBInner> Send for DBCommon<T, I> {}

// 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<T: ThreadMode, I: DBInner> Sync for DBCommon<T, I> {}

// Specifies whether open DB for read only.
enum AccessType<'a> {
    ReadWrite,
    ReadOnly { error_if_log_file_exist: bool },
    Secondary { secondary_path: &'a Path },
    WithTTL { ttl: Duration },
}

/// Methods of `DBWithThreadMode`.
impl<T: ThreadMode> DBWithThreadMode<T> {
    /// Opens a database with default options.
    pub fn open_default<P: AsRef<Path>>(path: P) -> Result<Self, Error> {
        let mut opts = Options::default();
        opts.create_if_missing(true);
        Self::open(&opts, path)
    }

    /// Opens the database with the specified options.
    pub fn open<P: AsRef<Path>>(opts: &Options, path: P) -> Result<Self, Error> {
        Self::open_cf(opts, path, None::<&str>)
    }

    /// Opens the database for read only with the specified options.
    pub fn open_for_read_only<P: AsRef<Path>>(
        opts: &Options,
        path: P,
        error_if_log_file_exist: bool,
    ) -> Result<Self, Error> {
        Self::open_cf_for_read_only(opts, path, None::<&str>, error_if_log_file_exist)
    }

    /// Opens the database as a secondary.
    pub fn open_as_secondary<P: AsRef<Path>>(
        opts: &Options,
        primary_path: P,
        secondary_path: P,
    ) -> Result<Self, Error> {
        Self::open_cf_as_secondary(opts, primary_path, secondary_path, None::<&str>)
    }

    /// Opens the database with a Time to Live compaction filter.
    ///
    /// This applies the given `ttl` to all column families created without an explicit TTL.
    /// See [`DB::open_cf_descriptors_with_ttl`] for more control over individual column family TTLs.
    pub fn open_with_ttl<P: AsRef<Path>>(
        opts: &Options,
        path: P,
        ttl: Duration,
    ) -> Result<Self, Error> {
        Self::open_cf_descriptors_with_ttl(opts, path, std::iter::empty(), ttl)
    }

    /// Opens the database with a Time to Live compaction filter and column family names.
    ///
    /// Column families opened using this function will be created with default `Options`.
    pub fn open_cf_with_ttl<P, I, N>(
        opts: &Options,
        path: P,
        cfs: I,
        ttl: Duration,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = N>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|name| ColumnFamilyDescriptor::new(name.as_ref(), Options::default()));

        Self::open_cf_descriptors_with_ttl(opts, path, cfs, ttl)
    }

    /// Opens a database with the given database with a Time to Live compaction filter and
    /// column family descriptors.
    ///
    /// Applies the provided `ttl` as the default TTL for all column families.
    /// Column families will inherit this TTL by default, unless their descriptor explicitly
    /// sets a different TTL using [`ColumnFamilyTtl::Duration`] or opts out using [`ColumnFamilyTtl::Disabled`].
    ///
    /// *NOTE*: The `default` column family is opened with `Options::default()` unless
    /// explicitly configured within the `cfs` iterator.
    /// To customize the `default` column family's options, include a `ColumnFamilyDescriptor`
    /// with the name "default" in the `cfs` iterator.
    ///
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_descriptors_with_ttl<P, I>(
        opts: &Options,
        path: P,
        cfs: I,
        ttl: Duration,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = ColumnFamilyDescriptor>,
    {
        Self::open_cf_descriptors_internal(opts, path, cfs, &AccessType::WithTTL { ttl })
    }

    /// Opens a database with the given database options and column family names.
    ///
    /// Column families opened using this function will be created with default `Options`.
    pub fn open_cf<P, I, N>(opts: &Options, path: P, cfs: I) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = N>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|name| ColumnFamilyDescriptor::new(name.as_ref(), Options::default()));

        Self::open_cf_descriptors_internal(opts, path, cfs, &AccessType::ReadWrite)
    }

    /// Opens a database with the given database options and column family names.
    ///
    /// Column families opened using given `Options`.
    pub fn open_cf_with_opts<P, I, N>(opts: &Options, path: P, cfs: I) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = (N, Options)>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|(name, opts)| ColumnFamilyDescriptor::new(name.as_ref(), opts));

        Self::open_cf_descriptors(opts, path, cfs)
    }

    /// Opens a database for read only with the given database options and column family names.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_for_read_only<P, I, N>(
        opts: &Options,
        path: P,
        cfs: I,
        error_if_log_file_exist: bool,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = N>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|name| ColumnFamilyDescriptor::new(name.as_ref(), Options::default()));

        Self::open_cf_descriptors_internal(
            opts,
            path,
            cfs,
            &AccessType::ReadOnly {
                error_if_log_file_exist,
            },
        )
    }

    /// Opens a database for read only with the given database options and column family names.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_with_opts_for_read_only<P, I, N>(
        db_opts: &Options,
        path: P,
        cfs: I,
        error_if_log_file_exist: bool,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = (N, Options)>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|(name, cf_opts)| ColumnFamilyDescriptor::new(name.as_ref(), cf_opts));

        Self::open_cf_descriptors_internal(
            db_opts,
            path,
            cfs,
            &AccessType::ReadOnly {
                error_if_log_file_exist,
            },
        )
    }

    /// Opens a database for ready only with the given database options and
    /// column family descriptors.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_descriptors_read_only<P, I>(
        opts: &Options,
        path: P,
        cfs: I,
        error_if_log_file_exist: bool,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = ColumnFamilyDescriptor>,
    {
        Self::open_cf_descriptors_internal(
            opts,
            path,
            cfs,
            &AccessType::ReadOnly {
                error_if_log_file_exist,
            },
        )
    }

    /// Opens the database as a secondary with the given database options and column family names.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_as_secondary<P, I, N>(
        opts: &Options,
        primary_path: P,
        secondary_path: P,
        cfs: I,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = N>,
        N: AsRef<str>,
    {
        let cfs = cfs
            .into_iter()
            .map(|name| ColumnFamilyDescriptor::new(name.as_ref(), Options::default()));

        Self::open_cf_descriptors_internal(
            opts,
            primary_path,
            cfs,
            &AccessType::Secondary {
                secondary_path: secondary_path.as_ref(),
            },
        )
    }

    /// Opens the database as a secondary with the given database options and
    /// column family descriptors.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_descriptors_as_secondary<P, I>(
        opts: &Options,
        path: P,
        secondary_path: P,
        cfs: I,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = ColumnFamilyDescriptor>,
    {
        Self::open_cf_descriptors_internal(
            opts,
            path,
            cfs,
            &AccessType::Secondary {
                secondary_path: secondary_path.as_ref(),
            },
        )
    }

    /// Opens a database with the given database options and column family descriptors.
    /// *NOTE*: `default` column family is opened with `Options::default()`.
    /// If you want to open `default` cf with different options, set them explicitly in `cfs`.
    pub fn open_cf_descriptors<P, I>(opts: &Options, path: P, cfs: I) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = ColumnFamilyDescriptor>,
    {
        Self::open_cf_descriptors_internal(opts, path, cfs, &AccessType::ReadWrite)
    }

    /// Internal implementation for opening RocksDB.
    fn open_cf_descriptors_internal<P, I>(
        opts: &Options,
        path: P,
        cfs: I,
        access_type: &AccessType,
    ) -> Result<Self, Error>
    where
        P: AsRef<Path>,
        I: IntoIterator<Item = ColumnFamilyDescriptor>,
    {
        let cfs: Vec<_> = cfs.into_iter().collect();
        let outlive = iter::once(opts.outlive.clone())
            .chain(cfs.iter().map(|cf| cf.options.outlive.clone()))
            .collect();

        let cpath = to_cpath(&path)?;

        if let Err(e) = fs::create_dir_all(&path) {
            return Err(Error::new(format!(
                "Failed to create RocksDB directory: `{e:?}`."
            )));
        }

        let db: *mut ffi::rocksdb_t;
        let mut cf_map = BTreeMap::new();

        if cfs.is_empty() {
            db = Self::open_raw(opts, &cpath, access_type)?;
        } else {
            let mut cfs_v = cfs;
            // Always open the default column family.
            if !cfs_v.iter().any(|cf| cf.name == DEFAULT_COLUMN_FAMILY_NAME) {
                cfs_v.push(ColumnFamilyDescriptor {
                    name: String::from(DEFAULT_COLUMN_FAMILY_NAME),
                    options: Options::default(),
                    ttl: ColumnFamilyTtl::SameAsDb,
                });
            }
            // We need to store our CStrings in an intermediate vector
            // so that their pointers remain valid.
            let c_cfs: Vec<CString> = cfs_v
                .iter()
                .map(|cf| CString::new(cf.name.as_bytes()).unwrap())
                .collect();

            let cfnames: Vec<_> = c_cfs.iter().map(|cf| cf.as_ptr()).collect();

            // These handles will be populated by DB.
            let mut cfhandles: Vec<_> = cfs_v.iter().map(|_| ptr::null_mut()).collect();

            let cfopts: Vec<_> = cfs_v
                .iter()
                .map(|cf| cf.options.inner.cast_const())
                .collect();

            db = Self::open_cf_raw(
                opts,
                &cpath,
                &cfs_v,
                &cfnames,
                &cfopts,
                &mut cfhandles,
                access_type,
            )?;
            for handle in &cfhandles {
                if handle.is_null() {
                    return Err(Error::new(
                        "Received null column family handle from DB.".to_owned(),
                    ));
                }
            }

            for (cf_desc, inner) in cfs_v.iter().zip(cfhandles) {
                cf_map.insert(cf_desc.name.clone(), inner);
            }
        }

        if db.is_null() {
            return Err(Error::new("Could not initialize database.".to_owned()));
        }

        Ok(Self {
            inner: DBWithThreadModeInner { inner: db },
            path: path.as_ref().to_path_buf(),
            cfs: T::new_cf_map_internal(cf_map),
            _outlive: outlive,
        })
    }

    fn open_raw(
        opts: &Options,
        cpath: &CString,
        access_type: &AccessType,
    ) -> Result<*mut ffi::rocksdb_t, Error> {
        let db = unsafe {
            match *access_type {
                AccessType::ReadOnly {
                    error_if_log_file_exist,
                } => ffi_try!(ffi::rocksdb_open_for_read_only(
                    opts.inner,
                    cpath.as_ptr(),
                    c_uchar::from(error_if_log_file_exist),
                )),
                AccessType::ReadWrite => {
                    ffi_try!(ffi::rocksdb_open(opts.inner, cpath.as_ptr()))
                }
                AccessType::Secondary { secondary_path } => {
                    ffi_try!(ffi::rocksdb_open_as_secondary(
                        opts.inner,
                        cpath.as_ptr(),
                        to_cpath(secondary_path)?.as_ptr(),
                    ))
                }
                AccessType::WithTTL { ttl } => ffi_try!(ffi::rocksdb_open_with_ttl(
                    opts.inner,
                    cpath.as_ptr(),
                    ttl.as_secs() as c_int,
                )),
            }
        };
        Ok(db)
    }

    #[allow(clippy::pedantic)]
    fn open_cf_raw(
        opts: &Options,
        cpath: &CString,
        cfs_v: &[ColumnFamilyDescriptor],
        cfnames: &[*const c_char],
        cfopts: &[*const ffi::rocksdb_options_t],
        cfhandles: &mut [*mut ffi::rocksdb_column_family_handle_t],
        access_type: &AccessType,
    ) -> Result<*mut ffi::rocksdb_t, Error> {
        let db = unsafe {
            match *access_type {
                AccessType::ReadOnly {
                    error_if_log_file_exist,
                } => ffi_try!(ffi::rocksdb_open_for_read_only_column_families(
                    opts.inner,
                    cpath.as_ptr(),
                    cfs_v.len() as c_int,
                    cfnames.as_ptr(),
                    cfopts.as_ptr(),
                    cfhandles.as_mut_ptr(),
                    c_uchar::from(error_if_log_file_exist),
                )),
                AccessType::ReadWrite => ffi_try!(ffi::rocksdb_open_column_families(
                    opts.inner,
                    cpath.as_ptr(),
                    cfs_v.len() as c_int,
                    cfnames.as_ptr(),
                    cfopts.as_ptr(),
                    cfhandles.as_mut_ptr(),
                )),
                AccessType::Secondary { secondary_path } => {
                    ffi_try!(ffi::rocksdb_open_as_secondary_column_families(
                        opts.inner,
                        cpath.as_ptr(),
                        to_cpath(secondary_path)?.as_ptr(),
                        cfs_v.len() as c_int,
                        cfnames.as_ptr(),
                        cfopts.as_ptr(),
                        cfhandles.as_mut_ptr(),
                    ))
                }
                AccessType::WithTTL { ttl } => {
                    let ttls: Vec<_> = cfs_v
                        .iter()
                        .map(|cf| match cf.ttl {
                            ColumnFamilyTtl::Disabled => i32::MAX,
                            ColumnFamilyTtl::Duration(duration) => duration.as_secs() as i32,
                            ColumnFamilyTtl::SameAsDb => ttl.as_secs() as i32,
                        })
                        .collect();

                    ffi_try!(ffi::rocksdb_open_column_families_with_ttl(
                        opts.inner,
                        cpath.as_ptr(),
                        cfs_v.len() as c_int,
                        cfnames.as_ptr(),
                        cfopts.as_ptr(),
                        cfhandles.as_mut_ptr(),
                        ttls.as_ptr(),
                    ))
                }
            }
        };
        Ok(db)
    }

    /// Removes the database entries in the range `["from", "to")` using given write options.
    pub fn delete_range_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        from: K,
        to: K,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        let from = from.as_ref();
        let to = to.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_delete_range_cf(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                from.as_ptr() as *const c_char,
                from.len() as size_t,
                to.as_ptr() as *const c_char,
                to.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Removes the database entries in the range `["from", "to")` using default write options.
    pub fn delete_range_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        from: K,
        to: K,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.delete_range_cf_opt(cf, from, to, opts))
    }

    pub fn write_opt(&self, batch: &WriteBatch, writeopts: &WriteOptions) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_write(
                self.inner.inner(),
                writeopts.inner,
                batch.inner
            ));
        }
        Ok(())
    }

    pub fn write(&self, batch: &WriteBatch) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.write_opt(batch, opts))
    }

    pub fn write_without_wal(&self, batch: &WriteBatch) -> Result<(), Error> {
        let mut wo = WriteOptions::new();
        wo.disable_wal(true);
        self.write_opt(batch, &wo)
    }

    pub fn write_wbwi(&self, wbwi: &WriteBatchWithIndex) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.write_wbwi_opt(wbwi, opts))
    }

    pub fn write_wbwi_opt(
        &self,
        wbwi: &WriteBatchWithIndex,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_write_writebatch_wi(
                self.inner.inner(),
                writeopts.inner,
                wbwi.inner
            ));

            Ok(())
        }
    }

    /// Suspend deleting obsolete files. Compactions will continue to occur,
    /// but no obsolete files will be deleted. To resume file deletions, each
    /// call to disable_file_deletions() must be matched by a subsequent call to
    /// enable_file_deletions(). For more details, see enable_file_deletions().
    pub fn disable_file_deletions(&self) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_disable_file_deletions(self.inner.inner()));
        }
        Ok(())
    }

    /// Resume deleting obsolete files, following up on `disable_file_deletions()`.
    ///
    /// File deletions disabling and enabling is not controlled by a binary flag,
    /// instead it's represented as a counter to allow different callers to
    /// independently disable file deletion. Disabling file deletion can be
    /// critical for operations like making a backup. So the counter implementation
    /// makes the file deletion disabled as long as there is one caller requesting
    /// so, and only when every caller agrees to re-enable file deletion, it will
    /// be enabled. Two threads can call this method concurrently without
    /// synchronization -- i.e., file deletions will be enabled only after both
    /// threads call enable_file_deletions()
    pub fn enable_file_deletions(&self) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_enable_file_deletions(self.inner.inner()));
        }
        Ok(())
    }
}

/// Common methods of `DBWithThreadMode` and `OptimisticTransactionDB`.
impl<T: ThreadMode, D: DBInner> DBCommon<T, D> {
    pub(crate) fn new(inner: D, cfs: T, path: PathBuf, outlive: Vec<OptionsMustOutliveDB>) -> Self {
        Self {
            inner,
            cfs,
            path,
            _outlive: outlive,
        }
    }

    pub fn list_cf<P: AsRef<Path>>(opts: &Options, path: P) -> Result<Vec<String>, Error> {
        let cpath = to_cpath(path)?;
        let mut length = 0;

        unsafe {
            let ptr = ffi_try!(ffi::rocksdb_list_column_families(
                opts.inner,
                cpath.as_ptr(),
                &raw mut length,
            ));

            let vec = slice::from_raw_parts(ptr, length)
                .iter()
                .map(|ptr| from_cstr_without_free(*ptr))
                .collect();
            ffi::rocksdb_list_column_families_destroy(ptr, length);
            Ok(vec)
        }
    }

    pub fn destroy<P: AsRef<Path>>(opts: &Options, path: P) -> Result<(), Error> {
        let cpath = to_cpath(path)?;
        unsafe {
            ffi_try!(ffi::rocksdb_destroy_db(opts.inner, cpath.as_ptr()));
        }
        Ok(())
    }

    pub fn repair<P: AsRef<Path>>(opts: &Options, path: P) -> Result<(), Error> {
        let cpath = to_cpath(path)?;
        unsafe {
            ffi_try!(ffi::rocksdb_repair_db(opts.inner, cpath.as_ptr()));
        }
        Ok(())
    }

    pub fn path(&self) -> &Path {
        self.path.as_path()
    }

    /// Flushes the WAL buffer. If `sync` is set to `true`, also syncs
    /// the data to disk.
    pub fn flush_wal(&self, sync: bool) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_flush_wal(
                self.inner.inner(),
                c_uchar::from(sync)
            ));
        }
        Ok(())
    }

    /// Flushes database memtables to SST files on the disk.
    pub fn flush_opt(&self, flushopts: &FlushOptions) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_flush(self.inner.inner(), flushopts.inner));
        }
        Ok(())
    }

    /// Flushes database memtables to SST files on the disk using default options.
    pub fn flush(&self) -> Result<(), Error> {
        self.flush_opt(&FlushOptions::default())
    }

    /// Flushes database memtables to SST files on the disk for a given column family.
    pub fn flush_cf_opt(
        &self,
        cf: &impl AsColumnFamilyRef,
        flushopts: &FlushOptions,
    ) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_flush_cf(
                self.inner.inner(),
                flushopts.inner,
                cf.inner()
            ));
        }
        Ok(())
    }

    /// Flushes multiple column families.
    ///
    /// If atomic flush is not enabled, it is equivalent to calling flush_cf multiple times.
    /// If atomic flush is enabled, it will flush all column families specified in `cfs` up to the latest sequence
    /// number at the time when flush is requested.
    pub fn flush_cfs_opt(
        &self,
        cfs: &[&impl AsColumnFamilyRef],
        opts: &FlushOptions,
    ) -> Result<(), Error> {
        let mut cfs = cfs.iter().map(|cf| cf.inner()).collect::<Vec<_>>();
        unsafe {
            ffi_try!(ffi::rocksdb_flush_cfs(
                self.inner.inner(),
                opts.inner,
                cfs.as_mut_ptr(),
                cfs.len() as libc::c_int,
            ));
        }
        Ok(())
    }

    /// Flushes database memtables to SST files on the disk for a given column family using default
    /// options.
    pub fn flush_cf(&self, cf: &impl AsColumnFamilyRef) -> Result<(), Error> {
        DEFAULT_FLUSH_OPTS.with(|opts| self.flush_cf_opt(cf, opts))
    }

    /// Return the bytes associated with a key value with read options. If you only intend to use
    /// the vector returned temporarily, consider using [`get_pinned_opt`](#method.get_pinned_opt)
    /// to avoid unnecessary memory copy.
    pub fn get_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error> {
        self.get_pinned_opt(key, readopts)
            .map(|x| x.map(|v| v.as_ref().to_vec()))
    }

    /// Return the bytes associated with a key value. If you only intend to use the vector returned
    /// temporarily, consider using [`get_pinned`](#method.get_pinned) to avoid unnecessary memory
    /// copy.
    pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Result<Option<Vec<u8>>, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_opt(key.as_ref(), opts))
    }

    /// Return the bytes associated with a key value and the given column family with read options.
    /// If you only intend to use the vector returned temporarily, consider using
    /// [`get_pinned_cf_opt`](#method.get_pinned_cf_opt) to avoid unnecessary memory.
    pub fn get_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<Vec<u8>>, Error> {
        self.get_pinned_cf_opt(cf, key, readopts)
            .map(|x| x.map(|v| v.as_ref().to_vec()))
    }

    /// Return the bytes associated with a key value and the given column family. If you only
    /// intend to use the vector returned temporarily, consider using
    /// [`get_pinned_cf`](#method.get_pinned_cf) to avoid unnecessary memory.
    pub fn get_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
    ) -> Result<Option<Vec<u8>>, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_cf_opt(cf, key.as_ref(), opts))
    }

    /// Return the value associated with a key using RocksDB's PinnableSlice
    /// so as to avoid unnecessary memory copy.
    pub fn get_pinned_opt<K: AsRef<[u8]>>(
        &'_ self,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        if readopts.inner.is_null() {
            return Err(Error::new(
                "Unable to create RocksDB read options. This is a fairly trivial call, and its \
                 failure may be indicative of a mis-compiled or mis-loaded RocksDB library."
                    .to_owned(),
            ));
        }

        let key = key.as_ref();
        unsafe {
            let val = ffi_try!(ffi::rocksdb_get_pinned(
                self.inner.inner(),
                readopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            if val.is_null() {
                Ok(None)
            } else {
                Ok(Some(DBPinnableSlice::from_c(val)))
            }
        }
    }

    /// Return the value associated with a key using RocksDB's PinnableSlice
    /// so as to avoid unnecessary memory copy. Similar to get_pinned_opt but
    /// leverages default options.
    pub fn get_pinned<K: AsRef<[u8]>>(
        &'_ self,
        key: K,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_pinned_opt(key, opts))
    }

    /// Return the value associated with a key using RocksDB's PinnableSlice
    /// so as to avoid unnecessary memory copy. Similar to get_pinned_opt but
    /// allows specifying ColumnFamily
    pub fn get_pinned_cf_opt<K: AsRef<[u8]>>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        if readopts.inner.is_null() {
            return Err(Error::new(
                "Unable to create RocksDB read options. This is a fairly trivial call, and its \
                 failure may be indicative of a mis-compiled or mis-loaded RocksDB library."
                    .to_owned(),
            ));
        }

        let key = key.as_ref();
        unsafe {
            let val = ffi_try!(ffi::rocksdb_get_pinned_cf(
                self.inner.inner(),
                readopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            if val.is_null() {
                Ok(None)
            } else {
                Ok(Some(DBPinnableSlice::from_c(val)))
            }
        }
    }

    /// Return the value associated with a key using RocksDB's PinnableSlice
    /// so as to avoid unnecessary memory copy. Similar to get_pinned_cf_opt but
    /// leverages default options.
    pub fn get_pinned_cf<K: AsRef<[u8]>>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        key: K,
    ) -> Result<Option<DBPinnableSlice<'_>>, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_pinned_cf_opt(cf, key, opts))
    }

    /// Read a value directly into a caller-provided buffer, avoiding memory allocation.
    ///
    /// This is the most efficient way to read values when you have a pre-allocated
    /// buffer. It completely avoids the allocation overhead of [`get`](#method.get)
    /// and even the pinning overhead of [`get_pinned`](#method.get_pinned).
    ///
    /// # Arguments
    ///
    /// * `key` - The key to look up
    /// * `buffer` - A mutable byte slice to write the value into. Can be empty if you
    ///   only want to check if a key exists and get its value size.
    ///
    /// # Returns
    ///
    /// * `Ok(GetIntoBufferResult::NotFound)` - The key doesn't exist
    /// * `Ok(GetIntoBufferResult::Found(size))` - Value was copied into the buffer.
    ///   `size` is the number of bytes written.
    /// * `Ok(GetIntoBufferResult::BufferTooSmall(size))` - The value exists but the buffer
    ///   is too small. `size` is the actual value size needed. No data is written.
    /// * `Err(...)` - Database error occurred
    ///
    /// # Performance
    ///
    /// This method is ideal for high-throughput scenarios where you can reuse a buffer:
    ///
    /// ```ignore
    /// use rust_rocksdb::{DB, GetIntoBufferResult};
    ///
    /// let db: DB = /* open database */;
    /// let keys_to_lookup: Vec<&[u8]> = /* keys to look up */;
    /// let mut buffer = vec![0u8; 4096]; // Reusable buffer
    ///
    /// for key in keys_to_lookup {
    ///     match db.get_into_buffer(key, &mut buffer).unwrap() {
    ///         GetIntoBufferResult::Found(len) => {
    ///             process_value(&buffer[..len]);
    ///         }
    ///         GetIntoBufferResult::BufferTooSmall(needed) => {
    ///             buffer.resize(needed, 0);
    ///             // Retry with larger buffer...
    ///         }
    ///         GetIntoBufferResult::NotFound => {}
    ///     }
    /// }
    /// ```
    ///
    /// # Example
    ///
    /// ```
    /// use rust_rocksdb::{DB, GetIntoBufferResult};
    ///
    /// let tempdir = tempfile::Builder::new()
    ///     .prefix("rocksdb_get_into_buffer")
    ///     .tempdir()
    ///     .unwrap();
    /// let db = DB::open_default(tempdir.path()).unwrap();
    /// db.put(b"key", b"value").unwrap();
    ///
    /// let mut buffer = [0u8; 100];
    /// match db.get_into_buffer(b"key", &mut buffer).unwrap() {
    ///     GetIntoBufferResult::Found(size) => {
    ///         assert_eq!(&buffer[..size], b"value");
    ///     }
    ///     GetIntoBufferResult::NotFound => panic!("expected value"),
    ///     GetIntoBufferResult::BufferTooSmall(needed) => {
    ///         panic!("buffer too small, need {} bytes", needed)
    ///     }
    /// }
    /// ```
    pub fn get_into_buffer<K: AsRef<[u8]>>(
        &self,
        key: K,
        buffer: &mut [u8],
    ) -> Result<GetIntoBufferResult, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_into_buffer_opt(key, buffer, opts))
    }

    /// Read a value directly into a caller-provided buffer with custom read options.
    ///
    /// This is the same as [`get_into_buffer`](#method.get_into_buffer) but allows
    /// specifying custom [`ReadOptions`], such as setting a snapshot or fill cache behavior.
    ///
    /// See [`get_into_buffer`](#method.get_into_buffer) for full documentation.
    pub fn get_into_buffer_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        buffer: &mut [u8],
        readopts: &ReadOptions,
    ) -> Result<GetIntoBufferResult, Error> {
        if readopts.inner.is_null() {
            return Err(Error::new(
                "Unable to create RocksDB read options. This is a fairly trivial call, and its \
                 failure may be indicative of a mis-compiled or mis-loaded RocksDB library."
                    .to_owned(),
            ));
        }

        let key = key.as_ref();
        let mut val_len: size_t = 0;
        let mut found: c_uchar = 0;

        unsafe {
            let success = ffi_try!(ffi::rocksdb_get_into_buffer(
                self.inner.inner(),
                readopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                buffer.as_mut_ptr() as *mut c_char,
                buffer.len() as size_t,
                &raw mut val_len,
                &raw mut found,
            ));

            if found == 0 {
                Ok(GetIntoBufferResult::NotFound)
            } else if success != 0 {
                Ok(GetIntoBufferResult::Found(val_len))
            } else {
                Ok(GetIntoBufferResult::BufferTooSmall(val_len))
            }
        }
    }

    /// Read a value from a column family directly into a caller-provided buffer.
    ///
    /// This is the column family variant of [`get_into_buffer`](#method.get_into_buffer).
    /// See that method for full documentation on the zero-allocation buffer API.
    ///
    /// # Arguments
    ///
    /// * `cf` - The column family to read from
    /// * `key` - The key to look up
    /// * `buffer` - A mutable byte slice to write the value into
    pub fn get_into_buffer_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        buffer: &mut [u8],
    ) -> Result<GetIntoBufferResult, Error> {
        DEFAULT_READ_OPTS.with(|opts| self.get_into_buffer_cf_opt(cf, key, buffer, opts))
    }

    /// Read a value from a column family directly into a caller-provided buffer
    /// with custom read options.
    ///
    /// This is the column family variant of [`get_into_buffer_opt`](#method.get_into_buffer_opt).
    /// See [`get_into_buffer`](#method.get_into_buffer) for full documentation.
    pub fn get_into_buffer_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        buffer: &mut [u8],
        readopts: &ReadOptions,
    ) -> Result<GetIntoBufferResult, Error> {
        if readopts.inner.is_null() {
            return Err(Error::new(
                "Unable to create RocksDB read options. This is a fairly trivial call, and its \
                 failure may be indicative of a mis-compiled or mis-loaded RocksDB library."
                    .to_owned(),
            ));
        }

        let key = key.as_ref();
        let mut val_len: size_t = 0;
        let mut found: c_uchar = 0;

        unsafe {
            let success = ffi_try!(ffi::rocksdb_get_into_buffer_cf(
                self.inner.inner(),
                readopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                buffer.as_mut_ptr() as *mut c_char,
                buffer.len() as size_t,
                &raw mut val_len,
                &raw mut found,
            ));

            if found == 0 {
                Ok(GetIntoBufferResult::NotFound)
            } else if success != 0 {
                Ok(GetIntoBufferResult::Found(val_len))
            } else {
                Ok(GetIntoBufferResult::BufferTooSmall(val_len))
            }
        }
    }

    /// Return the values associated with the given keys.
    pub fn multi_get<K, I>(&self, keys: I) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = K>,
    {
        DEFAULT_READ_OPTS.with(|opts| self.multi_get_opt(keys, opts))
    }

    /// Return the values associated with the given keys using read options.
    pub fn multi_get_opt<K, I>(
        &self,
        keys: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = K>,
    {
        let owned_keys: Vec<K> = keys.into_iter().collect();
        let (ptr_keys, keys_sizes): (Vec<*const c_char>, Vec<usize>) = owned_keys
            .iter()
            .map(|k| {
                let key = k.as_ref();
                (key.as_ptr() as *const c_char, key.len())
            })
            .unzip();

        let mut values: Vec<*mut c_char> = Vec::with_capacity(ptr_keys.len());
        let mut values_sizes: Vec<usize> = Vec::with_capacity(ptr_keys.len());
        let mut errors: Vec<*mut c_char> = Vec::with_capacity(ptr_keys.len());
        unsafe {
            ffi::rocksdb_multi_get(
                self.inner.inner(),
                readopts.inner,
                ptr_keys.len(),
                ptr_keys.as_ptr(),
                keys_sizes.as_ptr(),
                values.as_mut_ptr(),
                values_sizes.as_mut_ptr(),
                errors.as_mut_ptr(),
            );
        }

        unsafe {
            values.set_len(ptr_keys.len());
            values_sizes.set_len(ptr_keys.len());
            errors.set_len(ptr_keys.len());
        }

        convert_values(values, values_sizes, errors)
    }

    /// Returns pinned values associated with the given keys using default read options.
    ///
    /// This iterates `get_pinned_opt` for each key and returns zero-copy
    /// `DBPinnableSlice` values when present, avoiding value copies.
    pub fn multi_get_pinned<K, I>(
        &'_ self,
        keys: I,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = K>,
    {
        DEFAULT_READ_OPTS.with(|opts| self.multi_get_pinned_opt(keys, opts))
    }

    /// Returns pinned values associated with the given keys using the provided read options.
    ///
    /// This iterates `get_pinned_opt` for each key and returns zero-copy
    /// `DBPinnableSlice` values when present, avoiding value copies.
    pub fn multi_get_pinned_opt<K, I>(
        &'_ self,
        keys: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = K>,
    {
        keys.into_iter()
            .map(|k| self.get_pinned_opt(k, readopts))
            .collect()
    }

    /// Returns pinned values associated with the given keys and column families
    /// using default read options.
    pub fn multi_get_pinned_cf<'a, 'b: 'a, K, I, W>(
        &'a self,
        keys: I,
    ) -> Vec<Result<Option<DBPinnableSlice<'a>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = (&'b W, K)>,
        W: 'b + AsColumnFamilyRef,
    {
        DEFAULT_READ_OPTS.with(|opts| self.multi_get_pinned_cf_opt(keys, opts))
    }

    /// Returns pinned values associated with the given keys and column families
    /// using the provided read options.
    pub fn multi_get_pinned_cf_opt<'a, 'b: 'a, K, I, W>(
        &'a self,
        keys: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<DBPinnableSlice<'a>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = (&'b W, K)>,
        W: 'b + AsColumnFamilyRef,
    {
        keys.into_iter()
            .map(|(cf, k)| self.get_pinned_cf_opt(cf, k, readopts))
            .collect()
    }

    /// Return the values associated with the given keys and column families.
    pub fn multi_get_cf<'a, 'b: 'a, K, I, W>(
        &'a self,
        keys: I,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = (&'b W, K)>,
        W: 'b + AsColumnFamilyRef,
    {
        DEFAULT_READ_OPTS.with(|opts| self.multi_get_cf_opt(keys, opts))
    }

    /// Return the values associated with the given keys and column families using read options.
    pub fn multi_get_cf_opt<'a, 'b: 'a, K, I, W>(
        &'a self,
        keys: I,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<Vec<u8>>, Error>>
    where
        K: AsRef<[u8]>,
        I: IntoIterator<Item = (&'b W, K)>,
        W: 'b + AsColumnFamilyRef,
    {
        let cfs_and_owned_keys: Vec<(&'b W, K)> = keys.into_iter().collect();
        let (ptr_keys, keys_sizes): (Vec<*const c_char>, Vec<usize>) = cfs_and_owned_keys
            .iter()
            .map(|(_, k)| {
                let key = k.as_ref();
                (key.as_ptr() as *const c_char, key.len())
            })
            .unzip();
        let ptr_cfs: Vec<*const ffi::rocksdb_column_family_handle_t> = cfs_and_owned_keys
            .iter()
            .map(|(c, _)| c.inner().cast_const())
            .collect();
        let mut values: Vec<*mut c_char> = Vec::with_capacity(ptr_keys.len());
        let mut values_sizes: Vec<usize> = Vec::with_capacity(ptr_keys.len());
        let mut errors: Vec<*mut c_char> = Vec::with_capacity(ptr_keys.len());
        unsafe {
            ffi::rocksdb_multi_get_cf(
                self.inner.inner(),
                readopts.inner,
                ptr_cfs.as_ptr(),
                ptr_keys.len(),
                ptr_keys.as_ptr(),
                keys_sizes.as_ptr(),
                values.as_mut_ptr(),
                values_sizes.as_mut_ptr(),
                errors.as_mut_ptr(),
            );
        }

        unsafe {
            values.set_len(ptr_keys.len());
            values_sizes.set_len(ptr_keys.len());
            errors.set_len(ptr_keys.len());
        }

        convert_values(values, values_sizes, errors)
    }

    /// Return the values associated with the given keys and the specified column family
    /// where internally the read requests are processed in batch if block-based table
    /// SST format is used.  It is a more optimized version of multi_get_cf.
    pub fn batched_multi_get_cf<'a, K, I>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        keys: I,
        sorted_input: bool,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]> + 'a + ?Sized,
        I: IntoIterator<Item = &'a K>,
    {
        DEFAULT_READ_OPTS.with(|opts| self.batched_multi_get_cf_opt(cf, keys, sorted_input, opts))
    }

    /// Return the values associated with the given keys and the specified column family
    /// where internally the read requests are processed in batch if block-based table
    /// SST format is used. It is a more optimized version of multi_get_cf_opt.
    pub fn batched_multi_get_cf_opt<'a, K, I>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        keys: I,
        sorted_input: bool,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]> + 'a + ?Sized,
        I: IntoIterator<Item = &'a K>,
    {
        let (ptr_keys, keys_sizes): (Vec<_>, Vec<_>) = keys
            .into_iter()
            .map(|k| {
                let k = k.as_ref();
                (k.as_ptr() as *const c_char, k.len())
            })
            .unzip();

        let mut pinned_values = vec![ptr::null_mut(); ptr_keys.len()];
        let mut errors = vec![ptr::null_mut(); ptr_keys.len()];

        unsafe {
            ffi::rocksdb_batched_multi_get_cf(
                self.inner.inner(),
                readopts.inner,
                cf.inner(),
                ptr_keys.len(),
                ptr_keys.as_ptr(),
                keys_sizes.as_ptr(),
                pinned_values.as_mut_ptr(),
                errors.as_mut_ptr(),
                sorted_input,
            );
            pinned_values
                .into_iter()
                .zip(errors)
                .map(|(v, e)| {
                    if e.is_null() {
                        if v.is_null() {
                            Ok(None)
                        } else {
                            Ok(Some(DBPinnableSlice::from_c(v)))
                        }
                    } else {
                        Err(convert_rocksdb_error(e))
                    }
                })
                .collect()
        }
    }

    /// Return the values associated with the given keys and the specified column family
    /// using an optimized slice-based API.
    ///
    /// This method uses RocksDB's optimized `rocksdb_batched_multi_get_cf_slice` C API,
    /// which takes a `rocksdb_slice_t` array directly. This eliminates the internal
    /// overhead of converting keys from separate pointer+size arrays to Slice objects.
    ///
    /// # Arguments
    ///
    /// * `cf` - The column family to read from
    /// * `keys` - An iterator of keys to look up
    /// * `sorted_input` - If `true`, indicates the keys are already sorted in ascending
    ///   order, which allows RocksDB to skip internal sorting and improve performance.
    ///   **Important**: If you pass `true` but keys are not sorted, results may be incorrect.
    ///
    /// # Returns
    ///
    /// A vector of results in the same order as the input keys. Each element is:
    /// - `Ok(Some(DBPinnableSlice))` if the key was found
    /// - `Ok(None)` if the key was not found
    /// - `Err(...)` if an error occurred for that key
    ///
    /// # Performance
    ///
    /// This is the fastest batch lookup method when:
    /// - You're looking up many keys (10+) from the same column family
    /// - You can pre-sort your keys (set `sorted_input = true`)
    /// - Block-based table format is used (default)
    ///
    /// For small numbers of keys, the overhead of batching may not be worth it.
    /// Consider using [`get_pinned_cf`](#method.get_pinned_cf) for single key lookups.
    ///
    /// # Example
    ///
    /// ```
    /// use rust_rocksdb::{DB, Options, ColumnFamilyDescriptor};
    ///
    /// let tempdir = tempfile::Builder::new().prefix("batch_slice").tempdir().unwrap();
    /// let mut opts = Options::default();
    /// opts.create_if_missing(true);
    /// opts.create_missing_column_families(true);
    /// let db = DB::open_cf_descriptors(&opts, tempdir.path(),
    ///     vec![ColumnFamilyDescriptor::new("cf", Options::default())]).unwrap();
    ///
    /// let cf = db.cf_handle("cf").unwrap();
    /// db.put_cf(&cf, b"k1", b"v1").unwrap();
    /// db.put_cf(&cf, b"k2", b"v2").unwrap();
    ///
    /// // Keys are sorted, so we can set sorted_input = true
    /// let keys: Vec<&[u8]> = vec![b"k1", b"k2", b"k3"];
    /// let results = db.batched_multi_get_cf_slice(&cf, keys, true);
    ///
    /// assert!(results[0].as_ref().unwrap().is_some()); // k1 found
    /// assert!(results[1].as_ref().unwrap().is_some()); // k2 found
    /// assert!(results[2].as_ref().unwrap().is_none()); // k3 not found
    /// ```
    pub fn batched_multi_get_cf_slice<'a, K, I>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        keys: I,
        sorted_input: bool,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]> + 'a + ?Sized,
        I: IntoIterator<Item = &'a K>,
    {
        DEFAULT_READ_OPTS
            .with(|opts| self.batched_multi_get_cf_slice_opt(cf, keys, sorted_input, opts))
    }

    /// Return the values associated with the given keys and the specified column family
    /// using an optimized slice-based API with custom read options.
    ///
    /// This is the same as [`batched_multi_get_cf_slice`](#method.batched_multi_get_cf_slice)
    /// but allows specifying custom [`ReadOptions`].
    ///
    /// See [`batched_multi_get_cf_slice`](#method.batched_multi_get_cf_slice) for full documentation.
    pub fn batched_multi_get_cf_slice_opt<'a, K, I>(
        &'_ self,
        cf: &impl AsColumnFamilyRef,
        keys: I,
        sorted_input: bool,
        readopts: &ReadOptions,
    ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
    where
        K: AsRef<[u8]> + 'a + ?Sized,
        I: IntoIterator<Item = &'a K>,
    {
        // Convert keys to rocksdb_slice_t array
        let slices: Vec<ffi::rocksdb_slice_t> = keys
            .into_iter()
            .map(|k| {
                let k = k.as_ref();
                ffi::rocksdb_slice_t {
                    data: k.as_ptr() as *const c_char,
                    size: k.len(),
                }
            })
            .collect();

        if slices.is_empty() {
            return Vec::new();
        }

        let mut pinned_values = vec![ptr::null_mut(); slices.len()];
        let mut errors = vec![ptr::null_mut(); slices.len()];

        unsafe {
            ffi::rocksdb_batched_multi_get_cf_slice(
                self.inner.inner(),
                readopts.inner,
                cf.inner(),
                slices.len(),
                slices.as_ptr(),
                pinned_values.as_mut_ptr(),
                errors.as_mut_ptr(),
                sorted_input,
            );
            pinned_values
                .into_iter()
                .zip(errors)
                .map(|(v, e)| {
                    if e.is_null() {
                        if v.is_null() {
                            Ok(None)
                        } else {
                            Ok(Some(DBPinnableSlice::from_c(v)))
                        }
                    } else {
                        Err(convert_rocksdb_error(e))
                    }
                })
                .collect()
        }
    }

    /// Returns `false` if the given key definitely doesn't exist in the database, otherwise returns
    /// `true`. This function uses default `ReadOptions`.
    pub fn key_may_exist<K: AsRef<[u8]>>(&self, key: K) -> bool {
        DEFAULT_READ_OPTS.with(|opts| self.key_may_exist_opt(key, opts))
    }

    /// Returns `false` if the given key definitely doesn't exist in the database, otherwise returns
    /// `true`.
    pub fn key_may_exist_opt<K: AsRef<[u8]>>(&self, key: K, readopts: &ReadOptions) -> bool {
        let key = key.as_ref();
        unsafe {
            0 != ffi::rocksdb_key_may_exist(
                self.inner.inner(),
                readopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ptr::null_mut(), /*value*/
                ptr::null_mut(), /*val_len*/
                ptr::null(),     /*timestamp*/
                0,               /*timestamp_len*/
                ptr::null_mut(), /*value_found*/
            )
        }
    }

    /// Returns `false` if the given key definitely doesn't exist in the specified column family,
    /// otherwise returns `true`. This function uses default `ReadOptions`.
    pub fn key_may_exist_cf<K: AsRef<[u8]>>(&self, cf: &impl AsColumnFamilyRef, key: K) -> bool {
        DEFAULT_READ_OPTS.with(|opts| self.key_may_exist_cf_opt(cf, key, opts))
    }

    /// Returns `false` if the given key definitely doesn't exist in the specified column family,
    /// otherwise returns `true`.
    pub fn key_may_exist_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> bool {
        let key = key.as_ref();
        0 != unsafe {
            ffi::rocksdb_key_may_exist_cf(
                self.inner.inner(),
                readopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ptr::null_mut(), /*value*/
                ptr::null_mut(), /*val_len*/
                ptr::null(),     /*timestamp*/
                0,               /*timestamp_len*/
                ptr::null_mut(), /*value_found*/
            )
        }
    }

    /// If the key definitely does not exist in the database, then this method
    /// returns `(false, None)`, else `(true, None)` if it may.
    /// If the key is found in memory, then it returns `(true, Some<CSlice>)`.
    ///
    /// This check is potentially lighter-weight than calling `get()`. One way
    /// to make this lighter weight is to avoid doing any IOs.
    pub fn key_may_exist_cf_opt_value<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        readopts: &ReadOptions,
    ) -> (bool, Option<CSlice>) {
        let key = key.as_ref();
        let mut val: *mut c_char = ptr::null_mut();
        let mut val_len: usize = 0;
        let mut value_found: c_uchar = 0;
        let may_exists = 0
            != unsafe {
                ffi::rocksdb_key_may_exist_cf(
                    self.inner.inner(),
                    readopts.inner,
                    cf.inner(),
                    key.as_ptr() as *const c_char,
                    key.len() as size_t,
                    &raw mut val,         /*value*/
                    &raw mut val_len,     /*val_len*/
                    ptr::null(),          /*timestamp*/
                    0,                    /*timestamp_len*/
                    &raw mut value_found, /*value_found*/
                )
            };
        // The value is only allocated (using malloc) and returned if it is found and
        // value_found isn't NULL. In that case the user is responsible for freeing it.
        if may_exists && value_found != 0 {
            (
                may_exists,
                Some(unsafe { CSlice::from_raw_parts(val, val_len) }),
            )
        } else {
            (may_exists, None)
        }
    }

    fn create_inner_cf_handle(
        &self,
        name: impl CStrLike,
        opts: &Options,
    ) -> Result<*mut ffi::rocksdb_column_family_handle_t, Error> {
        let cf_name = name.bake().map_err(|err| {
            Error::new(format!(
                "Failed to convert path to CString when creating cf: {err}"
            ))
        })?;

        // Can't use ffi_try: rocksdb_create_column_family has a bug where it allocates a
        // result that needs to be freed on error
        let mut err: *mut ::libc::c_char = ::std::ptr::null_mut();
        let cf_handle = unsafe {
            ffi::rocksdb_create_column_family(
                self.inner.inner(),
                opts.inner,
                cf_name.as_ptr(),
                &raw mut err,
            )
        };
        if !err.is_null() {
            if !cf_handle.is_null() {
                unsafe { ffi::rocksdb_column_family_handle_destroy(cf_handle) };
            }
            return Err(convert_rocksdb_error(err));
        }
        Ok(cf_handle)
    }

    pub fn iterator<'a: 'b, 'b>(
        &'a self,
        mode: IteratorMode,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        let readopts = ReadOptions::default();
        self.iterator_opt(mode, readopts)
    }

    pub fn iterator_opt<'a: 'b, 'b>(
        &'a self,
        mode: IteratorMode,
        readopts: ReadOptions,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        DBIteratorWithThreadMode::new(self, readopts, mode)
    }

    /// Opens an iterator using the provided ReadOptions.
    /// This is used when you want to iterate over a specific ColumnFamily with a modified ReadOptions
    pub fn iterator_cf_opt<'a: 'b, 'b>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
        readopts: ReadOptions,
        mode: IteratorMode,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        DBIteratorWithThreadMode::new_cf(self, cf_handle.inner(), readopts, mode)
    }

    /// Opens an iterator with `set_total_order_seek` enabled.
    /// This must be used to iterate across prefixes when `set_memtable_factory` has been called
    /// with a Hash-based implementation.
    pub fn full_iterator<'a: 'b, 'b>(
        &'a self,
        mode: IteratorMode,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        let mut opts = ReadOptions::default();
        opts.set_total_order_seek(true);
        DBIteratorWithThreadMode::new(self, opts, mode)
    }

    pub fn prefix_iterator<'a: 'b, 'b, P: AsRef<[u8]>>(
        &'a self,
        prefix: P,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        let mut opts = ReadOptions::default();
        opts.set_prefix_same_as_start(true);
        DBIteratorWithThreadMode::new(
            self,
            opts,
            IteratorMode::From(prefix.as_ref(), Direction::Forward),
        )
    }

    pub fn iterator_cf<'a: 'b, 'b>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
        mode: IteratorMode,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        let opts = ReadOptions::default();
        DBIteratorWithThreadMode::new_cf(self, cf_handle.inner(), opts, mode)
    }

    pub fn full_iterator_cf<'a: 'b, 'b>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
        mode: IteratorMode,
    ) -> DBIteratorWithThreadMode<'b, Self> {
        let mut opts = ReadOptions::default();
        opts.set_total_order_seek(true);
        DBIteratorWithThreadMode::new_cf(self, cf_handle.inner(), opts, mode)
    }

    pub fn prefix_iterator_cf<'a, P: AsRef<[u8]>>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
        prefix: P,
    ) -> DBIteratorWithThreadMode<'a, Self> {
        let mut opts = ReadOptions::default();
        opts.set_prefix_same_as_start(true);
        DBIteratorWithThreadMode::<'a, Self>::new_cf(
            self,
            cf_handle.inner(),
            opts,
            IteratorMode::From(prefix.as_ref(), Direction::Forward),
        )
    }

    /// Returns `true` if there exists at least one key with the given prefix
    /// in the default column family using default read options.
    ///
    /// When to use: prefer this for one-shot checks. It enables
    /// `prefix_same_as_start(true)` and bounds the iterator to the
    /// prefix via `PrefixRange`, minimizing stray IO per call.
    pub fn prefix_exists<P: AsRef<[u8]>>(&self, prefix: P) -> Result<bool, Error> {
        let p = prefix.as_ref();
        PREFIX_READ_OPTS.with(|rc| {
            let mut opts = rc.borrow_mut();
            opts.set_iterate_range(crate::PrefixRange(p));
            self.prefix_exists_opt(p, &opts)
        })
    }

    /// Returns `true` if there exists at least one key with the given prefix
    /// in the default column family using the provided read options.
    pub fn prefix_exists_opt<P: AsRef<[u8]>>(
        &self,
        prefix: P,
        readopts: &ReadOptions,
    ) -> Result<bool, Error> {
        let prefix = prefix.as_ref();
        let iter = unsafe { self.create_iterator(readopts) };
        let res = unsafe {
            ffi::rocksdb_iter_seek(
                iter,
                prefix.as_ptr() as *const c_char,
                prefix.len() as size_t,
            );
            if ffi::rocksdb_iter_valid(iter) != 0 {
                let mut key_len: size_t = 0;
                let key_ptr = ffi::rocksdb_iter_key(iter, &raw mut key_len);
                let key = slice::from_raw_parts(key_ptr.cast::<u8>(), key_len as usize);
                Ok(key.starts_with(prefix))
            } else if let Err(e) = (|| {
                // Check status to differentiate end-of-range vs error
                ffi_try!(ffi::rocksdb_iter_get_error(iter));
                Ok::<(), Error>(())
            })() {
                Err(e)
            } else {
                Ok(false)
            }
        };
        unsafe { ffi::rocksdb_iter_destroy(iter) };
        res
    }

    /// Creates a reusable prefix prober over the default column family using
    /// read options optimized for prefix probes.
    ///
    /// When to use: prefer this in hot loops with many checks per second. It
    /// reuses a raw iterator to avoid per-call allocation/FFI overhead. If you
    /// need custom tuning (e.g. async IO, readahead, cache-only), use
    /// `prefix_prober_with_opts`.
    pub fn prefix_prober(&self) -> PrefixProber<'_, Self> {
        let mut opts = ReadOptions::default();
        opts.set_prefix_same_as_start(true);
        PrefixProber {
            raw: DBRawIteratorWithThreadMode::new(self, opts),
        }
    }

    /// Creates a reusable prefix prober over the default column family using
    /// the provided read options (owned).
    ///
    /// When to use: advanced tuning for heavy workloads. Callers can set
    /// `set_async_io(true)`, `set_readahead_size`, `set_read_tier`, etc. Note:
    /// the prober owns `ReadOptions` to keep internal buffers alive.
    pub fn prefix_prober_with_opts(&self, readopts: ReadOptions) -> PrefixProber<'_, Self> {
        PrefixProber {
            raw: DBRawIteratorWithThreadMode::new(self, readopts),
        }
    }

    /// Creates a reusable prefix prober over the specified column family using
    /// read options optimized for prefix probes.
    pub fn prefix_prober_cf(&self, cf_handle: &impl AsColumnFamilyRef) -> PrefixProber<'_, Self> {
        let mut opts = ReadOptions::default();
        opts.set_prefix_same_as_start(true);
        PrefixProber {
            raw: DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), opts),
        }
    }

    /// Creates a reusable prefix prober over the specified column family using
    /// the provided read options (owned).
    ///
    /// When to use: advanced tuning for heavy workloads on a specific CF.
    pub fn prefix_prober_cf_with_opts(
        &self,
        cf_handle: &impl AsColumnFamilyRef,
        readopts: ReadOptions,
    ) -> PrefixProber<'_, Self> {
        PrefixProber {
            raw: DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), readopts),
        }
    }

    /// Returns `true` if there exists at least one key with the given prefix
    /// in the specified column family using default read options.
    ///
    /// When to use: one-shot checks on a CF. Enables
    /// `prefix_same_as_start(true)` and bounds the iterator via `PrefixRange`.
    pub fn prefix_exists_cf<P: AsRef<[u8]>>(
        &self,
        cf_handle: &impl AsColumnFamilyRef,
        prefix: P,
    ) -> Result<bool, Error> {
        let p = prefix.as_ref();
        PREFIX_READ_OPTS.with(|rc| {
            let mut opts = rc.borrow_mut();
            opts.set_iterate_range(crate::PrefixRange(p));
            self.prefix_exists_cf_opt(cf_handle, p, &opts)
        })
    }

    /// Returns `true` if there exists at least one key with the given prefix
    /// in the specified column family using the provided read options.
    pub fn prefix_exists_cf_opt<P: AsRef<[u8]>>(
        &self,
        cf_handle: &impl AsColumnFamilyRef,
        prefix: P,
        readopts: &ReadOptions,
    ) -> Result<bool, Error> {
        let prefix = prefix.as_ref();
        let iter = unsafe { self.create_iterator_cf(cf_handle.inner(), readopts) };
        let res = unsafe {
            ffi::rocksdb_iter_seek(
                iter,
                prefix.as_ptr() as *const c_char,
                prefix.len() as size_t,
            );
            if ffi::rocksdb_iter_valid(iter) != 0 {
                let mut key_len: size_t = 0;
                let key_ptr = ffi::rocksdb_iter_key(iter, &raw mut key_len);
                let key = slice::from_raw_parts(key_ptr.cast::<u8>(), key_len as usize);
                Ok(key.starts_with(prefix))
            } else if let Err(e) = (|| {
                ffi_try!(ffi::rocksdb_iter_get_error(iter));
                Ok::<(), Error>(())
            })() {
                Err(e)
            } else {
                Ok(false)
            }
        };
        unsafe { ffi::rocksdb_iter_destroy(iter) };
        res
    }

    /// Opens a raw iterator over the database, using the default read options
    pub fn raw_iterator<'a: 'b, 'b>(&'a self) -> DBRawIteratorWithThreadMode<'b, Self> {
        let opts = ReadOptions::default();
        DBRawIteratorWithThreadMode::new(self, opts)
    }

    /// Opens a raw iterator over the given column family, using the default read options
    pub fn raw_iterator_cf<'a: 'b, 'b>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
    ) -> DBRawIteratorWithThreadMode<'b, Self> {
        let opts = ReadOptions::default();
        DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), opts)
    }

    /// Opens a raw iterator over the database, using the given read options
    pub fn raw_iterator_opt<'a: 'b, 'b>(
        &'a self,
        readopts: ReadOptions,
    ) -> DBRawIteratorWithThreadMode<'b, Self> {
        DBRawIteratorWithThreadMode::new(self, readopts)
    }

    /// Opens a raw iterator over the given column family, using the given read options
    pub fn raw_iterator_cf_opt<'a: 'b, 'b>(
        &'a self,
        cf_handle: &impl AsColumnFamilyRef,
        readopts: ReadOptions,
    ) -> DBRawIteratorWithThreadMode<'b, Self> {
        DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), readopts)
    }

    pub fn snapshot(&'_ self) -> SnapshotWithThreadMode<'_, Self> {
        SnapshotWithThreadMode::<Self>::new(self)
    }

    pub fn put_opt<K, V>(&self, key: K, value: V, writeopts: &WriteOptions) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_put(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn put_cf_opt<K, V>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        value: V,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_put_cf(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Set the database entry for "key" to "value" with WriteOptions.
    /// If "key" already exists, it will coexist with previous entry.
    /// `Get` with a timestamp ts specified in ReadOptions will return
    /// the most recent key/value whose timestamp is smaller than or equal to ts.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn put_with_ts_opt<K, V, S>(
        &self,
        key: K,
        ts: S,
        value: V,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_put_with_ts(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Put with timestamp in a specific column family with WriteOptions.
    /// If "key" already exists, it will coexist with previous entry.
    /// `Get` with a timestamp ts specified in ReadOptions will return
    /// the most recent key/value whose timestamp is smaller than or equal to ts.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn put_cf_with_ts_opt<K, V, S>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
        value: V,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_put_cf_with_ts(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn merge_opt<K, V>(&self, key: K, value: V, writeopts: &WriteOptions) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_merge(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn merge_cf_opt<K, V>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        value: V,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let value = value.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_merge_cf(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                value.as_ptr() as *const c_char,
                value.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn delete_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        let key = key.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_delete(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn delete_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        let key = key.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_delete_cf(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Remove the database entry (if any) for "key" with WriteOptions.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn delete_with_ts_opt<K, S>(
        &self,
        key: K,
        ts: S,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_delete_with_ts(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Delete with timestamp in a specific column family with WriteOptions.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn delete_cf_with_ts_opt<K, S>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_delete_cf_with_ts(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
            ));
            Ok(())
        }
    }

    pub fn put<K, V>(&self, key: K, value: V) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS.with(|opts| self.put_opt(key, value, opts))
    }

    pub fn put_cf<K, V>(&self, cf: &impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS.with(|opts| self.put_cf_opt(cf, key, value, opts))
    }

    /// Set the database entry for "key" to "value".
    /// If "key" already exists, it will coexist with previous entry.
    /// `Get` with a timestamp ts specified in ReadOptions will return
    /// the most recent key/value whose timestamp is smaller than or equal to ts.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn put_with_ts<K, V, S>(&self, key: K, ts: S, value: V) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS
            .with(|opts| self.put_with_ts_opt(key.as_ref(), ts.as_ref(), value.as_ref(), opts))
    }

    /// Put with timestamp in a specific column family.
    /// If "key" already exists, it will coexist with previous entry.
    /// `Get` with a timestamp ts specified in ReadOptions will return
    /// the most recent key/value whose timestamp is smaller than or equal to ts.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn put_cf_with_ts<K, V, S>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
        value: V,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS.with(|opts| {
            self.put_cf_with_ts_opt(cf, key.as_ref(), ts.as_ref(), value.as_ref(), opts)
        })
    }

    pub fn merge<K, V>(&self, key: K, value: V) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS.with(|opts| self.merge_opt(key, value, opts))
    }

    pub fn merge_cf<K, V>(&self, cf: &impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        V: AsRef<[u8]>,
    {
        DEFAULT_WRITE_OPTS.with(|opts| self.merge_cf_opt(cf, key, value, opts))
    }

    pub fn delete<K: AsRef<[u8]>>(&self, key: K) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.delete_opt(key, opts))
    }

    pub fn delete_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.delete_cf_opt(cf, key, opts))
    }

    /// Remove the database entry (if any) for "key".
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn delete_with_ts<K: AsRef<[u8]>, S: AsRef<[u8]>>(
        &self,
        key: K,
        ts: S,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.delete_with_ts_opt(key, ts, opts))
    }

    /// Delete with timestamp in a specific column family.
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    pub fn delete_cf_with_ts<K: AsRef<[u8]>, S: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.delete_cf_with_ts_opt(cf, key, ts, opts))
    }

    /// Remove the database entry for "key" with WriteOptions.
    ///
    /// Requires that the key exists and was not overwritten. Returns OK on success,
    /// and a non-OK status on error. It is not an error if "key" did not exist in the database.
    ///
    /// If a key is overwritten (by calling Put() multiple times), then the result
    /// of calling SingleDelete() on this key is undefined. SingleDelete() only
    /// behaves correctly if there has been only one Put() for this key since the
    /// previous call to SingleDelete() for this key.
    ///
    /// This feature is currently an experimental performance optimization
    /// for a very specific workload. It is up to the caller to ensure that
    /// SingleDelete is only used for a key that is not deleted using Delete() or
    /// written using Merge(). Mixing SingleDelete operations with Deletes and
    /// Merges can result in undefined behavior.
    ///
    /// Note: consider setting options.sync = true.
    ///
    /// For more information, see <https://github.com/facebook/rocksdb/wiki/Single-Delete>
    pub fn single_delete_opt<K: AsRef<[u8]>>(
        &self,
        key: K,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        let key = key.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_singledelete(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Remove the database entry for "key" from a specific column family with WriteOptions.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_cf_opt<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        writeopts: &WriteOptions,
    ) -> Result<(), Error> {
        let key = key.as_ref();

        unsafe {
            ffi_try!(ffi::rocksdb_singledelete_cf(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Remove the database entry for "key" with WriteOptions.
    ///
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_with_ts_opt<K, S>(
        &self,
        key: K,
        ts: S,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_singledelete_with_ts(
                self.inner.inner(),
                writeopts.inner,
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Remove the database entry for "key" from a specific column family with WriteOptions.
    ///
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_cf_with_ts_opt<K, S>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
        writeopts: &WriteOptions,
    ) -> Result<(), Error>
    where
        K: AsRef<[u8]>,
        S: AsRef<[u8]>,
    {
        let key = key.as_ref();
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_singledelete_cf_with_ts(
                self.inner.inner(),
                writeopts.inner,
                cf.inner(),
                key.as_ptr() as *const c_char,
                key.len() as size_t,
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Remove the database entry for "key".
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete<K: AsRef<[u8]>>(&self, key: K) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.single_delete_opt(key, opts))
    }

    /// Remove the database entry for "key" from a specific column family.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.single_delete_cf_opt(cf, key, opts))
    }

    /// Remove the database entry for "key".
    ///
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_with_ts<K: AsRef<[u8]>, S: AsRef<[u8]>>(
        &self,
        key: K,
        ts: S,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.single_delete_with_ts_opt(key, ts, opts))
    }

    /// Remove the database entry for "key" from a specific column family.
    ///
    /// Takes an additional argument `ts` as the timestamp.
    /// Note: the DB must be opened with user defined timestamp enabled.
    ///
    /// See single_delete_opt() for detailed behavior and restrictions.
    pub fn single_delete_cf_with_ts<K: AsRef<[u8]>, S: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        key: K,
        ts: S,
    ) -> Result<(), Error> {
        DEFAULT_WRITE_OPTS.with(|opts| self.single_delete_cf_with_ts_opt(cf, key, ts, opts))
    }

    /// Runs a manual compaction on the Range of keys given. This is not likely to be needed for typical usage.
    pub fn compact_range<S: AsRef<[u8]>, E: AsRef<[u8]>>(&self, start: Option<S>, end: Option<E>) {
        unsafe {
            let start = start.as_ref().map(AsRef::as_ref);
            let end = end.as_ref().map(AsRef::as_ref);

            ffi::rocksdb_compact_range(
                self.inner.inner(),
                opt_bytes_to_ptr(start),
                start.map_or(0, <[u8]>::len) as size_t,
                opt_bytes_to_ptr(end),
                end.map_or(0, <[u8]>::len) as size_t,
            );
        }
    }

    /// Same as `compact_range` but with custom options.
    pub fn compact_range_opt<S: AsRef<[u8]>, E: AsRef<[u8]>>(
        &self,
        start: Option<S>,
        end: Option<E>,
        opts: &CompactOptions,
    ) {
        unsafe {
            let start = start.as_ref().map(AsRef::as_ref);
            let end = end.as_ref().map(AsRef::as_ref);

            ffi::rocksdb_compact_range_opt(
                self.inner.inner(),
                opts.inner,
                opt_bytes_to_ptr(start),
                start.map_or(0, <[u8]>::len) as size_t,
                opt_bytes_to_ptr(end),
                end.map_or(0, <[u8]>::len) as size_t,
            );
        }
    }

    /// Runs a manual compaction on the Range of keys given on the
    /// given column family. This is not likely to be needed for typical usage.
    pub fn compact_range_cf<S: AsRef<[u8]>, E: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        start: Option<S>,
        end: Option<E>,
    ) {
        unsafe {
            let start = start.as_ref().map(AsRef::as_ref);
            let end = end.as_ref().map(AsRef::as_ref);

            ffi::rocksdb_compact_range_cf(
                self.inner.inner(),
                cf.inner(),
                opt_bytes_to_ptr(start),
                start.map_or(0, <[u8]>::len) as size_t,
                opt_bytes_to_ptr(end),
                end.map_or(0, <[u8]>::len) as size_t,
            );
        }
    }

    /// Same as `compact_range_cf` but with custom options.
    pub fn compact_range_cf_opt<S: AsRef<[u8]>, E: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        start: Option<S>,
        end: Option<E>,
        opts: &CompactOptions,
    ) {
        unsafe {
            let start = start.as_ref().map(AsRef::as_ref);
            let end = end.as_ref().map(AsRef::as_ref);

            ffi::rocksdb_compact_range_cf_opt(
                self.inner.inner(),
                cf.inner(),
                opts.inner,
                opt_bytes_to_ptr(start),
                start.map_or(0, <[u8]>::len) as size_t,
                opt_bytes_to_ptr(end),
                end.map_or(0, <[u8]>::len) as size_t,
            );
        }
    }

    /// Wait for all flush and compactions jobs to finish. Jobs to wait include the
    /// unscheduled (queued, but not scheduled yet).
    ///
    /// NOTE: This may also never return if there's sufficient ongoing writes that
    /// keeps flush and compaction going without stopping. The user would have to
    /// cease all the writes to DB to make this eventually return in a stable
    /// state. The user may also use timeout option in WaitForCompactOptions to
    /// make this stop waiting and return when timeout expires.
    pub fn wait_for_compact(&self, opts: &WaitForCompactOptions) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_wait_for_compact(
                self.inner.inner(),
                opts.inner
            ));
        }
        Ok(())
    }

    pub fn set_options(&self, opts: &[(&str, &str)]) -> Result<(), Error> {
        let copts = convert_options(opts)?;
        let cnames: Vec<*const c_char> = copts.iter().map(|opt| opt.0.as_ptr()).collect();
        let cvalues: Vec<*const c_char> = copts.iter().map(|opt| opt.1.as_ptr()).collect();
        let count = opts.len() as i32;
        unsafe {
            ffi_try!(ffi::rocksdb_set_options(
                self.inner.inner(),
                count,
                cnames.as_ptr(),
                cvalues.as_ptr(),
            ));
        }
        Ok(())
    }

    pub fn set_options_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
        opts: &[(&str, &str)],
    ) -> Result<(), Error> {
        let copts = convert_options(opts)?;
        let cnames: Vec<*const c_char> = copts.iter().map(|opt| opt.0.as_ptr()).collect();
        let cvalues: Vec<*const c_char> = copts.iter().map(|opt| opt.1.as_ptr()).collect();
        let count = opts.len() as i32;
        unsafe {
            ffi_try!(ffi::rocksdb_set_options_cf(
                self.inner.inner(),
                cf.inner(),
                count,
                cnames.as_ptr(),
                cvalues.as_ptr(),
            ));
        }
        Ok(())
    }

    /// Implementation for property_value et al methods.
    ///
    /// `name` is the name of the property.  It will be converted into a CString
    /// and passed to `get_property` as argument.  `get_property` reads the
    /// specified property and either returns NULL or a pointer to a C allocated
    /// string; this method takes ownership of that string and will free it at
    /// the end. That string is parsed using `parse` callback which produces
    /// the returned result.
    fn property_value_impl<R>(
        name: impl CStrLike,
        get_property: impl FnOnce(*const c_char) -> *mut c_char,
        parse: impl FnOnce(&str) -> Result<R, Error>,
    ) -> Result<Option<R>, Error> {
        let value = match name.bake() {
            Ok(prop_name) => get_property(prop_name.as_ptr()),
            Err(e) => {
                return Err(Error::new(format!(
                    "Failed to convert property name to CString: {e}"
                )));
            }
        };
        if value.is_null() {
            return Ok(None);
        }
        let result = match unsafe { CStr::from_ptr(value) }.to_str() {
            Ok(s) => parse(s).map(|value| Some(value)),
            Err(e) => Err(Error::new(format!(
                "Failed to convert property value to string: {e}"
            ))),
        };
        unsafe {
            ffi::rocksdb_free(value as *mut c_void);
        }
        result
    }

    /// Retrieves a RocksDB property by name.
    ///
    /// Full list of properties could be find
    /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L428-L634).
    pub fn property_value(&self, name: impl CStrLike) -> Result<Option<String>, Error> {
        Self::property_value_impl(
            name,
            |prop_name| unsafe { ffi::rocksdb_property_value(self.inner.inner(), prop_name) },
            |str_value| Ok(str_value.to_owned()),
        )
    }

    /// Retrieves a RocksDB property by name, for a specific column family.
    ///
    /// Full list of properties could be find
    /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L428-L634).
    pub fn property_value_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
        name: impl CStrLike,
    ) -> Result<Option<String>, Error> {
        Self::property_value_impl(
            name,
            |prop_name| unsafe {
                ffi::rocksdb_property_value_cf(self.inner.inner(), cf.inner(), prop_name)
            },
            |str_value| Ok(str_value.to_owned()),
        )
    }

    fn parse_property_int_value(value: &str) -> Result<u64, Error> {
        value.parse::<u64>().map_err(|err| {
            Error::new(format!(
                "Failed to convert property value {value} to int: {err}"
            ))
        })
    }

    /// Retrieves a RocksDB property and casts it to an integer.
    ///
    /// Full list of properties that return int values could be find
    /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L654-L689).
    pub fn property_int_value(&self, name: impl CStrLike) -> Result<Option<u64>, Error> {
        Self::property_value_impl(
            name,
            |prop_name| unsafe { ffi::rocksdb_property_value(self.inner.inner(), prop_name) },
            Self::parse_property_int_value,
        )
    }

    /// Retrieves a RocksDB property for a specific column family and casts it to an integer.
    ///
    /// Full list of properties that return int values could be find
    /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L654-L689).
    pub fn property_int_value_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
        name: impl CStrLike,
    ) -> Result<Option<u64>, Error> {
        Self::property_value_impl(
            name,
            |prop_name| unsafe {
                ffi::rocksdb_property_value_cf(self.inner.inner(), cf.inner(), prop_name)
            },
            Self::parse_property_int_value,
        )
    }

    /// The sequence number of the most recent transaction.
    pub fn latest_sequence_number(&self) -> u64 {
        unsafe { ffi::rocksdb_get_latest_sequence_number(self.inner.inner()) }
    }

    /// Return the approximate file system space used by keys in each ranges.
    ///
    /// Note that the returned sizes measure file system space usage, so
    /// if the user data compresses by a factor of ten, the returned
    /// sizes will be one-tenth the size of the corresponding user data size.
    ///
    /// Due to lack of abi, only data flushed to disk is taken into account.
    pub fn get_approximate_sizes(&self, ranges: &[Range]) -> Vec<u64> {
        self.get_approximate_sizes_cfopt(None::<&ColumnFamily>, ranges)
    }

    pub fn get_approximate_sizes_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
        ranges: &[Range],
    ) -> Vec<u64> {
        self.get_approximate_sizes_cfopt(Some(cf), ranges)
    }

    fn get_approximate_sizes_cfopt(
        &self,
        cf: Option<&impl AsColumnFamilyRef>,
        ranges: &[Range],
    ) -> Vec<u64> {
        let start_keys: Vec<*const c_char> = ranges
            .iter()
            .map(|x| x.start_key.as_ptr() as *const c_char)
            .collect();
        let start_key_lens: Vec<_> = ranges.iter().map(|x| x.start_key.len()).collect();
        let end_keys: Vec<*const c_char> = ranges
            .iter()
            .map(|x| x.end_key.as_ptr() as *const c_char)
            .collect();
        let end_key_lens: Vec<_> = ranges.iter().map(|x| x.end_key.len()).collect();
        let mut sizes: Vec<u64> = vec![0; ranges.len()];
        let (n, start_key_ptr, start_key_len_ptr, end_key_ptr, end_key_len_ptr, size_ptr) = (
            ranges.len() as i32,
            start_keys.as_ptr(),
            start_key_lens.as_ptr(),
            end_keys.as_ptr(),
            end_key_lens.as_ptr(),
            sizes.as_mut_ptr(),
        );
        let mut err: *mut c_char = ptr::null_mut();
        match cf {
            None => unsafe {
                ffi::rocksdb_approximate_sizes(
                    self.inner.inner(),
                    n,
                    start_key_ptr,
                    start_key_len_ptr,
                    end_key_ptr,
                    end_key_len_ptr,
                    size_ptr,
                    &raw mut err,
                );
            },
            Some(cf) => unsafe {
                ffi::rocksdb_approximate_sizes_cf(
                    self.inner.inner(),
                    cf.inner(),
                    n,
                    start_key_ptr,
                    start_key_len_ptr,
                    end_key_ptr,
                    end_key_len_ptr,
                    size_ptr,
                    &raw mut err,
                );
            },
        }
        sizes
    }

    /// Iterate over batches of write operations since a given sequence.
    ///
    /// Produce an iterator that will provide the batches of write operations
    /// that have occurred since the given sequence (see
    /// `latest_sequence_number()`). Use the provided iterator to retrieve each
    /// (`u64`, `WriteBatch`) tuple, and then gather the individual puts and
    /// deletes using the `WriteBatch::iterate()` function.
    ///
    /// Calling `get_updates_since()` with a sequence number that is out of
    /// bounds will return an error.
    pub fn get_updates_since(&self, seq_number: u64) -> Result<DBWALIterator, Error> {
        unsafe {
            // rocksdb_wal_readoptions_t does not appear to have any functions
            // for creating and destroying it; fortunately we can pass a nullptr
            // here to get the default behavior
            let opts: *const ffi::rocksdb_wal_readoptions_t = ptr::null();
            let iter = ffi_try!(ffi::rocksdb_get_updates_since(
                self.inner.inner(),
                seq_number,
                opts
            ));
            Ok(DBWALIterator {
                inner: iter,
                start_seq_number: seq_number,
            })
        }
    }

    /// Tries to catch up with the primary by reading as much as possible from the
    /// log files.
    pub fn try_catch_up_with_primary(&self) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_try_catch_up_with_primary(self.inner.inner()));
        }
        Ok(())
    }

    /// Loads a list of external SST files created with SstFileWriter into the DB with default opts
    pub fn ingest_external_file<P: AsRef<Path>>(&self, paths: Vec<P>) -> Result<(), Error> {
        let opts = IngestExternalFileOptions::default();
        self.ingest_external_file_opts(&opts, paths)
    }

    /// Loads a list of external SST files created with SstFileWriter into the DB
    pub fn ingest_external_file_opts<P: AsRef<Path>>(
        &self,
        opts: &IngestExternalFileOptions,
        paths: Vec<P>,
    ) -> Result<(), Error> {
        let paths_v: Vec<CString> = paths.iter().map(to_cpath).collect::<Result<Vec<_>, _>>()?;
        let cpaths: Vec<_> = paths_v.iter().map(|path| path.as_ptr()).collect();

        self.ingest_external_file_raw(opts, &paths_v, &cpaths)
    }

    /// Loads a list of external SST files created with SstFileWriter into the DB for given Column Family
    /// with default opts
    pub fn ingest_external_file_cf<P: AsRef<Path>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        paths: Vec<P>,
    ) -> Result<(), Error> {
        let opts = IngestExternalFileOptions::default();
        self.ingest_external_file_cf_opts(cf, &opts, paths)
    }

    /// Loads a list of external SST files created with SstFileWriter into the DB for given Column Family
    pub fn ingest_external_file_cf_opts<P: AsRef<Path>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        opts: &IngestExternalFileOptions,
        paths: Vec<P>,
    ) -> Result<(), Error> {
        let paths_v: Vec<CString> = paths.iter().map(to_cpath).collect::<Result<Vec<_>, _>>()?;
        let cpaths: Vec<_> = paths_v.iter().map(|path| path.as_ptr()).collect();

        self.ingest_external_file_raw_cf(cf, opts, &paths_v, &cpaths)
    }

    fn ingest_external_file_raw(
        &self,
        opts: &IngestExternalFileOptions,
        paths_v: &[CString],
        cpaths: &[*const c_char],
    ) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_ingest_external_file(
                self.inner.inner(),
                cpaths.as_ptr(),
                paths_v.len(),
                opts.inner.cast_const()
            ));
            Ok(())
        }
    }

    fn ingest_external_file_raw_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
        opts: &IngestExternalFileOptions,
        paths_v: &[CString],
        cpaths: &[*const c_char],
    ) -> Result<(), Error> {
        unsafe {
            ffi_try!(ffi::rocksdb_ingest_external_file_cf(
                self.inner.inner(),
                cf.inner(),
                cpaths.as_ptr(),
                paths_v.len(),
                opts.inner.cast_const()
            ));
            Ok(())
        }
    }

    /// Obtains the LSM-tree meta data of the default column family of the DB
    pub fn get_column_family_metadata(&self) -> ColumnFamilyMetaData {
        unsafe {
            let ptr = ffi::rocksdb_get_column_family_metadata(self.inner.inner());

            let metadata = ColumnFamilyMetaData {
                size: ffi::rocksdb_column_family_metadata_get_size(ptr),
                name: from_cstr_and_free(ffi::rocksdb_column_family_metadata_get_name(ptr)),
                file_count: ffi::rocksdb_column_family_metadata_get_file_count(ptr),
            };

            // destroy
            ffi::rocksdb_column_family_metadata_destroy(ptr);

            // return
            metadata
        }
    }

    /// Obtains the LSM-tree meta data of the specified column family of the DB
    pub fn get_column_family_metadata_cf(
        &self,
        cf: &impl AsColumnFamilyRef,
    ) -> ColumnFamilyMetaData {
        unsafe {
            let ptr = ffi::rocksdb_get_column_family_metadata_cf(self.inner.inner(), cf.inner());

            let metadata = ColumnFamilyMetaData {
                size: ffi::rocksdb_column_family_metadata_get_size(ptr),
                name: from_cstr_and_free(ffi::rocksdb_column_family_metadata_get_name(ptr)),
                file_count: ffi::rocksdb_column_family_metadata_get_file_count(ptr),
            };

            // destroy
            ffi::rocksdb_column_family_metadata_destroy(ptr);

            // return
            metadata
        }
    }

    /// Returns a list of all table files with their level, start key
    /// and end key
    pub fn live_files(&self) -> Result<Vec<LiveFile>, Error> {
        unsafe {
            let livefiles_ptr = ffi::rocksdb_livefiles(self.inner.inner());
            if livefiles_ptr.is_null() {
                Err(Error::new("Could not get live files".to_owned()))
            } else {
                let files = LiveFile::from_rocksdb_livefiles_ptr(livefiles_ptr);

                // destroy livefiles metadata(s)
                ffi::rocksdb_livefiles_destroy(livefiles_ptr);

                // return
                Ok(files)
            }
        }
    }

    /// Delete sst files whose keys are entirely in the given range.
    ///
    /// Could leave some keys in the range which are in files which are not
    /// entirely in the range.
    ///
    /// Note: L0 files are left regardless of whether they're in the range.
    ///
    /// SnapshotWithThreadModes before the delete might not see the data in the given range.
    pub fn delete_file_in_range<K: AsRef<[u8]>>(&self, from: K, to: K) -> Result<(), Error> {
        let from = from.as_ref();
        let to = to.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_delete_file_in_range(
                self.inner.inner(),
                from.as_ptr() as *const c_char,
                from.len() as size_t,
                to.as_ptr() as *const c_char,
                to.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Same as `delete_file_in_range` but only for specific column family
    pub fn delete_file_in_range_cf<K: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        from: K,
        to: K,
    ) -> Result<(), Error> {
        let from = from.as_ref();
        let to = to.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_delete_file_in_range_cf(
                self.inner.inner(),
                cf.inner(),
                from.as_ptr() as *const c_char,
                from.len() as size_t,
                to.as_ptr() as *const c_char,
                to.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Request stopping background work, if wait is true wait until it's done.
    pub fn cancel_all_background_work(&self, wait: bool) {
        unsafe {
            ffi::rocksdb_cancel_all_background_work(self.inner.inner(), c_uchar::from(wait));
        }
    }

    fn drop_column_family<C>(
        &self,
        cf_inner: *mut ffi::rocksdb_column_family_handle_t,
        cf: C,
    ) -> Result<(), Error> {
        unsafe {
            // first mark the column family as dropped
            ffi_try!(ffi::rocksdb_drop_column_family(
                self.inner.inner(),
                cf_inner
            ));
        }
        // then finally reclaim any resources (mem, files) by destroying the only single column
        // family handle by drop()-ing it
        drop(cf);
        Ok(())
    }

    /// Increase the full_history_ts of column family. The new ts_low value should
    /// be newer than current full_history_ts value.
    /// If another thread updates full_history_ts_low concurrently to a higher
    /// timestamp than the requested ts_low, a try again error will be returned.
    pub fn increase_full_history_ts_low<S: AsRef<[u8]>>(
        &self,
        cf: &impl AsColumnFamilyRef,
        ts: S,
    ) -> Result<(), Error> {
        let ts = ts.as_ref();
        unsafe {
            ffi_try!(ffi::rocksdb_increase_full_history_ts_low(
                self.inner.inner(),
                cf.inner(),
                ts.as_ptr() as *const c_char,
                ts.len() as size_t,
            ));
            Ok(())
        }
    }

    /// Get current full_history_ts value.
    pub fn get_full_history_ts_low(&self, cf: &impl AsColumnFamilyRef) -> Result<Vec<u8>, Error> {
        unsafe {
            let mut ts_lowlen = 0;
            let ts = ffi_try!(ffi::rocksdb_get_full_history_ts_low(
                self.inner.inner(),
                cf.inner(),
                &raw mut ts_lowlen,
            ));

            if ts.is_null() {
                Err(Error::new("Could not get full_history_ts_low".to_owned()))
            } else {
                let mut vec = vec![0; ts_lowlen];
                ptr::copy_nonoverlapping(ts.cast::<u8>(), vec.as_mut_ptr(), ts_lowlen);
                ffi::rocksdb_free(ts as *mut c_void);
                Ok(vec)
            }
        }
    }

    /// Returns the DB identity. This is typically ASCII bytes, but that is not guaranteed.
    pub fn get_db_identity(&self) -> Result<Vec<u8>, Error> {
        unsafe {
            let mut length: usize = 0;
            let identity_ptr = ffi::rocksdb_get_db_identity(self.inner.inner(), &raw mut length);
            let identity_vec = raw_data(identity_ptr, length);
            ffi::rocksdb_free(identity_ptr as *mut c_void);
            // In RocksDB: get_db_identity copies a std::string so it should not fail, but
            // the API allows it to be overridden, so it might
            identity_vec.ok_or_else(|| Error::new("get_db_identity returned NULL".to_string()))
        }
    }
}

impl<I: DBInner> DBCommon<SingleThreaded, I> {
    /// Creates column family with given name and options
    pub fn create_cf<N: AsRef<str>>(&mut self, name: N, opts: &Options) -> Result<(), Error> {
        let inner = self.create_inner_cf_handle(name.as_ref(), opts)?;
        self.cfs
            .cfs
            .insert(name.as_ref().to_string(), ColumnFamily { inner });
        Ok(())
    }

    #[doc = include_str!("db_create_column_family_with_import.md")]
    pub fn create_column_family_with_import<N: AsRef<str>>(
        &mut self,
        options: &Options,
        column_family_name: N,
        import_options: &ImportColumnFamilyOptions,
        metadata: &ExportImportFilesMetaData,
    ) -> Result<(), Error> {
        let name = column_family_name.as_ref();
        let c_name = CString::new(name).map_err(|err| {
            Error::new(format!(
                "Failed to convert name to CString while importing column family: {err}"
            ))
        })?;
        let inner = unsafe {
            ffi_try!(ffi::rocksdb_create_column_family_with_import(
                self.inner.inner(),
                options.inner,
                c_name.as_ptr(),
                import_options.inner,
                metadata.inner
            ))
        };
        self.cfs
            .cfs
            .insert(column_family_name.as_ref().into(), ColumnFamily { inner });
        Ok(())
    }

    /// Drops the column family with the given name
    pub fn drop_cf(&mut self, name: &str) -> Result<(), Error> {
        match self.cfs.cfs.remove(name) {
            Some(cf) => self.drop_column_family(cf.inner, cf),
            _ => Err(Error::new(format!("Invalid column family: {name}"))),
        }
    }

    /// Returns the underlying column family handle
    pub fn cf_handle(&self, name: &str) -> Option<&ColumnFamily> {
        self.cfs.cfs.get(name)
    }

    /// Returns the list of column families currently open.
    ///
    /// The order of names is unspecified and may vary between calls.
    pub fn cf_names(&self) -> Vec<String> {
        self.cfs.cfs.keys().cloned().collect()
    }
}

impl<I: DBInner> DBCommon<MultiThreaded, I> {
    /// Creates column family with given name and options
    pub fn create_cf<N: AsRef<str>>(&self, name: N, opts: &Options) -> Result<(), Error> {
        // Note that we acquire the cfs lock before inserting: otherwise we might race
        // another caller who observed the handle as missing.
        let mut cfs = self.cfs.cfs.write();
        let inner = self.create_inner_cf_handle(name.as_ref(), opts)?;
        cfs.insert(
            name.as_ref().to_string(),
            Arc::new(UnboundColumnFamily { inner }),
        );
        Ok(())
    }

    #[doc = include_str!("db_create_column_family_with_import.md")]
    pub fn create_column_family_with_import<N: AsRef<str>>(
        &self,
        options: &Options,
        column_family_name: N,
        import_options: &ImportColumnFamilyOptions,
        metadata: &ExportImportFilesMetaData,
    ) -> Result<(), Error> {
        // Acquire CF lock upfront, before creating the CF, to avoid a race with concurrent creators
        let mut cfs = self.cfs.cfs.write();
        let name = column_family_name.as_ref();
        let c_name = CString::new(name).map_err(|err| {
            Error::new(format!(
                "Failed to convert name to CString while importing column family: {err}"
            ))
        })?;
        let inner = unsafe {
            ffi_try!(ffi::rocksdb_create_column_family_with_import(
                self.inner.inner(),
                options.inner,
                c_name.as_ptr(),
                import_options.inner,
                metadata.inner
            ))
        };
        cfs.insert(
            column_family_name.as_ref().to_string(),
            Arc::new(UnboundColumnFamily { inner }),
        );
        Ok(())
    }

    /// Drops the column family with the given name by internally locking the inner column
    /// family map. This avoids needing `&mut self` reference
    pub fn drop_cf(&self, name: &str) -> Result<(), Error> {
        match self.cfs.cfs.write().remove(name) {
            Some(cf) => self.drop_column_family(cf.inner, cf),
            _ => Err(Error::new(format!("Invalid column family: {name}"))),
        }
    }

    /// Returns the underlying column family handle
    pub fn cf_handle(&'_ self, name: &str) -> Option<Arc<BoundColumnFamily<'_>>> {
        self.cfs
            .cfs
            .read()
            .get(name)
            .cloned()
            .map(UnboundColumnFamily::bound_column_family)
    }

    /// Returns the list of column families currently open.
    ///
    /// The order of names is unspecified and may vary between calls.
    pub fn cf_names(&self) -> Vec<String> {
        self.cfs.cfs.read().keys().cloned().collect()
    }
}

impl<T: ThreadMode, I: DBInner> Drop for DBCommon<T, I> {
    fn drop(&mut self) {
        self.cfs.drop_all_cfs_internal();
    }
}

impl<T: ThreadMode, I: DBInner> fmt::Debug for DBCommon<T, I> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "RocksDB {{ path: {} }}", self.path().display())
    }
}

/// The metadata that describes a column family.
#[derive(Debug, Clone)]
pub struct ColumnFamilyMetaData {
    // The size of this column family in bytes, which is equal to the sum of
    // the file size of its "levels".
    pub size: u64,
    // The name of the column family.
    pub name: String,
    // The number of files in this column family.
    pub file_count: usize,
}

/// The metadata that describes a SST file
#[derive(Debug, Clone)]
pub struct LiveFile {
    /// Name of the column family the file belongs to
    pub column_family_name: String,
    /// Name of the file
    pub name: String,
    /// The directory containing the file, without a trailing '/'. This could be
    /// a DB path, wal_dir, etc.
    pub directory: String,
    /// Size of the file
    pub size: usize,
    /// Level at which this file resides
    pub level: i32,
    /// Smallest user defined key in the file
    pub start_key: Option<Vec<u8>>,
    /// Largest user defined key in the file
    pub end_key: Option<Vec<u8>>,
    pub smallest_seqno: u64,
    pub largest_seqno: u64,
    /// Number of entries/alive keys in the file
    pub num_entries: u64,
    /// Number of deletions/tomb key(s) in the file
    pub num_deletions: u64,
}

impl LiveFile {
    /// Create a `Vec<LiveFile>` from a `rocksdb_livefiles_t` pointer
    pub(crate) fn from_rocksdb_livefiles_ptr(
        files: *const ffi::rocksdb_livefiles_t,
    ) -> Vec<LiveFile> {
        unsafe {
            let n = ffi::rocksdb_livefiles_count(files);

            let mut livefiles = Vec::with_capacity(n as usize);
            let mut key_size: usize = 0;

            for i in 0..n {
                // rocksdb_livefiles_* returns pointers to strings, not copies
                let column_family_name =
                    from_cstr_without_free(ffi::rocksdb_livefiles_column_family_name(files, i));
                let name = from_cstr_without_free(ffi::rocksdb_livefiles_name(files, i));
                let directory = from_cstr_without_free(ffi::rocksdb_livefiles_directory(files, i));
                let size = ffi::rocksdb_livefiles_size(files, i);
                let level = ffi::rocksdb_livefiles_level(files, i);

                // get smallest key inside file
                let smallest_key = ffi::rocksdb_livefiles_smallestkey(files, i, &raw mut key_size);
                let smallest_key = raw_data(smallest_key, key_size);

                // get largest key inside file
                let largest_key = ffi::rocksdb_livefiles_largestkey(files, i, &raw mut key_size);
                let largest_key = raw_data(largest_key, key_size);

                livefiles.push(LiveFile {
                    column_family_name,
                    name,
                    directory,
                    size,
                    level,
                    start_key: smallest_key,
                    end_key: largest_key,
                    largest_seqno: ffi::rocksdb_livefiles_largest_seqno(files, i),
                    smallest_seqno: ffi::rocksdb_livefiles_smallest_seqno(files, i),
                    num_entries: ffi::rocksdb_livefiles_entries(files, i),
                    num_deletions: ffi::rocksdb_livefiles_deletions(files, i),
                });
            }

            livefiles
        }
    }
}

struct LiveFileGuard(*mut rocksdb_livefile_t);

impl LiveFileGuard {
    fn into_raw(mut self) -> *mut rocksdb_livefile_t {
        let ptr = self.0;
        self.0 = ptr::null_mut();
        ptr
    }
}

impl Drop for LiveFileGuard {
    fn drop(&mut self) {
        if !self.0.is_null() {
            unsafe {
                rocksdb_livefile_destroy(self.0);
            }
        }
    }
}

struct LiveFilesGuard(*mut rocksdb_livefiles_t);

impl LiveFilesGuard {
    fn into_raw(mut self) -> *mut rocksdb_livefiles_t {
        let ptr = self.0;
        self.0 = ptr::null_mut();
        ptr
    }
}

impl Drop for LiveFilesGuard {
    fn drop(&mut self) {
        if !self.0.is_null() {
            unsafe {
                rocksdb_livefiles_destroy(self.0);
            }
        }
    }
}

/// Metadata returned as output from [`Checkpoint::export_column_family`][export_column_family] and
/// used as input to [`DB::create_column_family_with_import`].
///
/// [export_column_family]: crate::checkpoint::Checkpoint::export_column_family
#[derive(Debug)]
pub struct ExportImportFilesMetaData {
    pub(crate) inner: *mut ffi::rocksdb_export_import_files_metadata_t,
}

impl ExportImportFilesMetaData {
    pub fn get_db_comparator_name(&self) -> String {
        unsafe {
            let c_name =
                ffi::rocksdb_export_import_files_metadata_get_db_comparator_name(self.inner);
            from_cstr_and_free(c_name)
        }
    }

    pub fn set_db_comparator_name(&mut self, name: &str) {
        let c_name = CString::new(name.as_bytes()).unwrap();
        unsafe {
            ffi::rocksdb_export_import_files_metadata_set_db_comparator_name(
                self.inner,
                c_name.as_ptr(),
            );
        };
    }

    pub fn get_files(&self) -> Vec<LiveFile> {
        unsafe {
            let livefiles_ptr = ffi::rocksdb_export_import_files_metadata_get_files(self.inner);
            let files = LiveFile::from_rocksdb_livefiles_ptr(livefiles_ptr);
            ffi::rocksdb_livefiles_destroy(livefiles_ptr);
            files
        }
    }

    pub fn set_files(&mut self, files: &[LiveFile]) -> Result<(), Error> {
        // Use a non-null empty pointer for zero-length keys
        static EMPTY: [u8; 0] = [];
        let empty_ptr = EMPTY.as_ptr() as *const libc::c_char;

        unsafe {
            let live_files = LiveFilesGuard(ffi::rocksdb_livefiles_create());

            for file in files {
                let live_file = LiveFileGuard(ffi::rocksdb_livefile_create());
                ffi::rocksdb_livefile_set_level(live_file.0, file.level);

                // SAFETY: C strings are copied inside the FFI layer so do not need to be kept alive
                let c_cf_name = CString::new(file.column_family_name.as_str()).map_err(|err| {
                    Error::new(format!("Unable to convert column family to CString: {err}"))
                })?;
                ffi::rocksdb_livefile_set_column_family_name(live_file.0, c_cf_name.as_ptr());

                let c_name = CString::new(file.name.as_str()).map_err(|err| {
                    Error::new(format!("Unable to convert file name to CString: {err}"))
                })?;
                ffi::rocksdb_livefile_set_name(live_file.0, c_name.as_ptr());

                let c_directory = CString::new(file.directory.as_str()).map_err(|err| {
                    Error::new(format!("Unable to convert directory to CString: {err}"))
                })?;
                ffi::rocksdb_livefile_set_directory(live_file.0, c_directory.as_ptr());

                ffi::rocksdb_livefile_set_size(live_file.0, file.size);

                let (start_key_ptr, start_key_len) = match &file.start_key {
                    None => (empty_ptr, 0),
                    Some(key) => (key.as_ptr() as *const libc::c_char, key.len()),
                };
                ffi::rocksdb_livefile_set_smallest_key(live_file.0, start_key_ptr, start_key_len);

                let (largest_key_ptr, largest_key_len) = match &file.end_key {
                    None => (empty_ptr, 0),
                    Some(key) => (key.as_ptr() as *const libc::c_char, key.len()),
                };
                ffi::rocksdb_livefile_set_largest_key(
                    live_file.0,
                    largest_key_ptr,
                    largest_key_len,
                );
                ffi::rocksdb_livefile_set_smallest_seqno(live_file.0, file.smallest_seqno);
                ffi::rocksdb_livefile_set_largest_seqno(live_file.0, file.largest_seqno);
                ffi::rocksdb_livefile_set_num_entries(live_file.0, file.num_entries);
                ffi::rocksdb_livefile_set_num_deletions(live_file.0, file.num_deletions);

                // moves ownership of live_files into live_file
                ffi::rocksdb_livefiles_add(live_files.0, live_file.into_raw());
            }

            // moves ownership of live_files into inner
            ffi::rocksdb_export_import_files_metadata_set_files(self.inner, live_files.into_raw());
            Ok(())
        }
    }
}

impl Default for ExportImportFilesMetaData {
    fn default() -> Self {
        let inner = unsafe { ffi::rocksdb_export_import_files_metadata_create() };
        assert!(
            !inner.is_null(),
            "Could not create rocksdb_export_import_files_metadata_t"
        );

        Self { inner }
    }
}

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

unsafe impl Send for ExportImportFilesMetaData {}
unsafe impl Sync for ExportImportFilesMetaData {}

fn convert_options(opts: &[(&str, &str)]) -> Result<Vec<(CString, CString)>, Error> {
    opts.iter()
        .map(|(name, value)| {
            let cname = match CString::new(name.as_bytes()) {
                Ok(cname) => cname,
                Err(e) => return Err(Error::new(format!("Invalid option name `{e}`"))),
            };
            let cvalue = match CString::new(value.as_bytes()) {
                Ok(cvalue) => cvalue,
                Err(e) => return Err(Error::new(format!("Invalid option value: `{e}`"))),
            };
            Ok((cname, cvalue))
        })
        .collect()
}

pub(crate) fn convert_values(
    values: Vec<*mut c_char>,
    values_sizes: Vec<usize>,
    errors: Vec<*mut c_char>,
) -> Vec<Result<Option<Vec<u8>>, Error>> {
    values
        .into_iter()
        .zip(values_sizes)
        .zip(errors)
        .map(|((v, s), e)| {
            if e.is_null() {
                let value = unsafe { crate::ffi_util::raw_data(v, s) };
                unsafe {
                    ffi::rocksdb_free(v as *mut c_void);
                }
                Ok(value)
            } else {
                Err(convert_rocksdb_error(e))
            }
        })
        .collect()
}