openethereum/util/src/kvdb.rs

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2016-02-18 03:46:34 +01:00
// 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 <http://www.gnu.org/licenses/>.
//! 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<usize>
}
/// 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, String> {
Database::open(DatabaseConfig { prefix_size: None }, path)
}
/// Open database file. Creates if it does not exist.
pub fn open(config: DatabaseConfig, path: &str) -> Result<Database, String> {
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<Option<DBVector>, 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<Box<[u8]>> {
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) }
}
}