diff --git a/util/src/kvdb.rs b/util/src/kvdb.rs new file mode 100644 index 000000000..a5691bcba --- /dev/null +++ b/util/src/kvdb.rs @@ -0,0 +1,150 @@ +// Copyright 2015, 2016 Ethcore (UK) Ltd. +// This file is part of Parity. + +// Parity is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. + +// Parity is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License +// along with Parity. If not, see . + +//! Key-Value store abstraction with rocksb backend. + +use rocksdb::{DB, Writable, WriteBatch, IteratorMode, DBVector, DBIterator, + IndexType, Options, DBCompactionStyle, BlockBasedOptions, Direction}; + +/// Write transaction. Batches a sequence of put/delete operations for efficiency. +pub struct DBTransaction { + batch: WriteBatch, +} + +impl DBTransaction { + /// Create new transaction. + pub fn new() -> DBTransaction { + DBTransaction { batch: WriteBatch::new() } + } + + /// Insert a ket-value pair in the transaction. Any existing value value will be overwritten upon write. + pub fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> { + self.batch.put(key, value) + } + + /// Delete value by key. + pub fn delete(&self, key: &[u8]) -> Result<(), String> { + self.batch.delete(key) + } +} + +/// Database configuration +pub struct DatabaseConfig { + /// Optional prefix size in bytes. Allows lookup by partial key. + pub prefix_size: Option +} + +/// Database iterator +pub struct DatabaseIterator<'a> { + iter: DBIterator<'a>, +} + +impl<'a> Iterator for DatabaseIterator<'a> { + type Item = (Box<[u8]>, Box<[u8]>); + + #[allow(type_complexity)] + fn next(&mut self) -> Option<(Box<[u8]>, Box<[u8]>)> { + self.iter.next() + } +} + +/// Key-Value database. +pub struct Database { + db: DB, +} + +impl Database { + /// Open database with default settings. + pub fn open_default(path: &str) -> Result { + Database::open(DatabaseConfig { prefix_size: None }, path) + } + + /// Open database file. Creates if it does not exist. + pub fn open(config: DatabaseConfig, path: &str) -> Result { + let mut opts = Options::new(); + opts.set_max_open_files(256); + opts.create_if_missing(true); + opts.set_use_fsync(false); + opts.set_compaction_style(DBCompactionStyle::DBUniversalCompaction); + /* + opts.set_bytes_per_sync(8388608); + opts.set_disable_data_sync(false); + opts.set_block_cache_size_mb(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(DBUniversalCompaction); + opts.set_max_background_compactions(4); + opts.set_max_background_flushes(4); + opts.set_filter_deletes(false); + opts.set_disable_auto_compactions(false);*/ + + if let Some(size) = config.prefix_size { + let mut block_opts = BlockBasedOptions::new(); + block_opts.set_index_type(IndexType::HashSearch); + opts.set_block_based_table_factory(&block_opts); + opts.set_prefix_extractor_fixed_size(size); + } + let db = try!(DB::open(&opts, path)); + Ok(Database { db: db }) + } + + /// Insert a ket-value pair in the transaction. Any existing value value will be overwritten. + pub fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> { + self.db.put(key, value) + } + + /// Delete value by key. + pub fn delete(&self, key: &[u8]) -> Result<(), String> { + self.db.delete(key) + } + + /// Commit transaction to database. + pub fn write(&self, tr: DBTransaction) -> Result<(), String> { + self.db.write(tr.batch) + } + + /// Get value by key. + pub fn get(&self, key: &[u8]) -> Result, String> { + self.db.get(key) + } + + /// Get value by partial key. Prefix size should match configured prefix size. + pub fn get_by_prefix(&self, prefix: &[u8]) -> Option> { + let mut iter = self.db.iterator(IteratorMode::From(prefix, Direction::forward)); + match iter.next() { + // TODO: use prefix_same_as_start read option (not availabele in C API currently) + Some((k, v)) => if k[0 .. prefix.len()] == prefix[..] { Some(v) } else { None }, + _ => None + } + } + + /// Check if there is anything in the database. + pub fn is_empty(&self) -> bool { + self.db.iterator(IteratorMode::Start).next().is_none() + } + + /// Check if there is anything in the database. + pub fn iter(&self) -> DatabaseIterator { + DatabaseIterator { iter: self.db.iterator(IteratorMode::Start) } + } +} + +