mappum_rocksdb/

lib.rs

// Copyright 2014 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.
//

//! Rust wrapper for RocksDB.
//!
//! # Examples
//!
//! ```
//! use rocksdb::{DB, Options};
//! // NB: db is automatically closed at end of lifetime
//! let path = "_path_for_rocksdb_storage";
//! {
//!    let db = DB::open_default(path).unwrap();
//!    db.put(b"my key", b"my value").unwrap();
//!    match db.get(b"my key") {
//!        Ok(Some(value)) => println!("retrieved value {}", String::from_utf8(value).unwrap()),
//!        Ok(None) => println!("value not found"),
//!        Err(e) => println!("operational problem encountered: {}", e),
//!    }
//!    db.delete(b"my key").unwrap();
//! }
//! let _ = DB::destroy(&Options::default(), path);
//! ```
//!
//! Opening a database and a single column family with custom options:
//!
//! ```
//! use rocksdb::{DB, ColumnFamilyDescriptor, Options};
//!
//! let path = "_path_for_rocksdb_storage_with_cfs";
//! let mut cf_opts = Options::default();
//! cf_opts.set_max_write_buffer_number(16);
//! let cf = ColumnFamilyDescriptor::new("cf1", cf_opts);
//!
//! let mut db_opts = Options::default();
//! db_opts.create_missing_column_families(true);
//! db_opts.create_if_missing(true);
//! {
//!     let db = DB::open_cf_descriptors(&db_opts, path, vec![cf]).unwrap();
//! }
//! let _ = DB::destroy(&db_opts, path);
//! ```
//!

#[macro_use]
mod ffi_util;

pub mod backup;
pub mod checkpoint;
pub mod compaction_filter;
mod comparator;
mod db;
mod db_options;
pub mod merge_operator;
mod slice_transform;

pub use crate::{
    compaction_filter::Decision as CompactionDecision,
    db::{
        DBCompactionStyle, DBCompressionType, DBIterator, DBPinnableSlice, DBRawIterator,
        DBRecoveryMode, DBWALIterator, Direction, IteratorMode, ReadOptions, Snapshot, WriteBatch,
        WriteBatchIterator,
    },
    merge_operator::MergeOperands,
    slice_transform::SliceTransform,
};

use librocksdb_sys as ffi;

use std::collections::BTreeMap;
use std::error;
use std::fmt;
use std::path::PathBuf;

/// A RocksDB database.
///
/// See crate level documentation for a simple usage example.
pub struct DB {
    inner: *mut ffi::rocksdb_t,
    cfs: BTreeMap<String, ColumnFamily>,
    path: PathBuf,
}

/// A descriptor for a RocksDB column family.
///
/// A description of the column family, containing the name and `Options`.
pub struct ColumnFamilyDescriptor {
    name: String,
    options: Options,
}

/// A simple wrapper round a string, used for errors reported from
/// ffi calls.
#[derive(Debug, Clone, PartialEq)]
pub struct Error {
    message: String,
}

impl Error {
    fn new(message: String) -> Error {
        Error { message }
    }

    pub fn into_string(self) -> String {
        self.into()
    }
}

impl AsRef<str> for Error {
    fn as_ref(&self) -> &str {
        &self.message
    }
}

impl From<Error> for String {
    fn from(e: Error) -> String {
        e.message
    }
}

impl error::Error for Error {
    fn description(&self) -> &str {
        &self.message
    }
}

impl fmt::Display for Error {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        self.message.fmt(formatter)
    }
}

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

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

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

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

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

/// Used with DBOptions::set_plain_table_factory.
/// See https://github.com/facebook/rocksdb/wiki/PlainTable-Format.
///
/// Defaults:
///  user_key_length: 0 (variable length)
///  bloom_bits_per_key: 10
///  hash_table_ratio: 0.75
///  index_sparseness: 16
pub struct PlainTableFactoryOptions {
    pub user_key_length: u32,
    pub bloom_bits_per_key: i32,
    pub hash_table_ratio: f64,
    pub index_sparseness: usize,
}

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

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

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

/// An opaque type used to represent a column family. Returned from some functions, and used
/// in others
pub struct ColumnFamily {
    inner: *mut ffi::rocksdb_column_family_handle_t,
}

unsafe impl Send for ColumnFamily {}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn is_send() {
        // test (at compile time) that certain types implement the auto-trait Send, either directly for
        // pointer-wrapping types or transitively for types with all Send fields

        fn is_send<T: Send>() {
            // dummy function just used for its parameterized type bound
        }

        is_send::<DB>();
        is_send::<DBIterator<'_>>();
        is_send::<DBRawIterator<'_>>();
        is_send::<Snapshot>();
        is_send::<Options>();
        is_send::<ReadOptions>();
        is_send::<WriteOptions>();
        is_send::<BlockBasedOptions>();
        is_send::<PlainTableFactoryOptions>();
        is_send::<ColumnFamilyDescriptor>();
        is_send::<ColumnFamily>();
    }

    #[test]
    fn is_sync() {
        // test (at compile time) that certain types implement the auto-trait Sync

        fn is_sync<T: Sync>() {
            // dummy function just used for its parameterized type bound
        }

        is_sync::<DB>();
        is_sync::<Snapshot>();
        is_sync::<Options>();
        is_sync::<ReadOptions>();
        is_sync::<WriteOptions>();
        is_sync::<BlockBasedOptions>();
        is_sync::<PlainTableFactoryOptions>();
        is_sync::<ColumnFamilyDescriptor>();
    }
}