openethereum/util/src/kvdb.rs

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// 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/>.
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//! Key-Value store abstraction with RocksDB backend.
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use std::default::Default;
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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,
}
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impl Default for DBTransaction {
fn default() -> Self {
DBTransaction::new()
}
}
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impl DBTransaction {
/// Create new transaction.
pub fn new() -> DBTransaction {
DBTransaction { batch: WriteBatch::new() }
}
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/// Insert a key-value pair in the transaction. Any existing value value will be overwritten upon write.
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pub fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
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self.batch.put(key, value)
}
/// Delete value by key.
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pub fn delete(&self, key: &[u8]) -> Result<(), String> {
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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> {
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iter: DBIterator<'a>,
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}
impl<'a> Iterator for DatabaseIterator<'a> {
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type Item = (Box<[u8]>, Box<[u8]>);
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fn next(&mut self) -> Option<Self::Item> {
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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> {
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Database::open(&DatabaseConfig { prefix_size: None }, path)
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}
/// Open database file. Creates if it does not exist.
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pub fn open(config: &DatabaseConfig, path: &str) -> Result<Database, String> {
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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);
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opts.set_disable_auto_compactions(false);
*/
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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 })
}
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/// Insert a key-value pair in the transaction. Any existing value value will be overwritten.
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pub fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
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self.db.put(key, value)
}
/// Delete value by key.
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pub fn delete(&self, key: &[u8]) -> Result<(), String> {
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self.db.delete(key)
}
/// Commit transaction to database.
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pub fn write(&self, tr: DBTransaction) -> Result<(), String> {
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self.db.write(tr.batch)
}
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/// Get value by key.
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pub fn get(&self, key: &[u8]) -> Result<Option<DBVector>, String> {
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self.db.get(key)
}
/// Get value by partial key. Prefix size should match configured prefix size.
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pub fn get_by_prefix(&self, prefix: &[u8]) -> Option<Box<[u8]>> {
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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) }
}
}
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#[cfg(test)]
mod tests {
use hash::*;
use super::*;
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use devtools::*;
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use std::str::FromStr;
use std::ops::Deref;
fn test_db(config: &DatabaseConfig) {
let path = RandomTempPath::create_dir();
let db = Database::open(config, path.as_path().to_str().unwrap()).unwrap();
let key1 = H256::from_str("02c69be41d0b7e40352fc85be1cd65eb03d40ef8427a0ca4596b1ead9a00e9fc").unwrap();
let key2 = H256::from_str("03c69be41d0b7e40352fc85be1cd65eb03d40ef8427a0ca4596b1ead9a00e9fc").unwrap();
let key3 = H256::from_str("01c69be41d0b7e40352fc85be1cd65eb03d40ef8427a0ca4596b1ead9a00e9fc").unwrap();
db.put(&key1, b"cat").unwrap();
db.put(&key2, b"dog").unwrap();
assert_eq!(db.get(&key1).unwrap().unwrap().deref(), b"cat");
let contents: Vec<_> = db.iter().collect();
assert_eq!(contents.len(), 2);
assert_eq!(&*contents[0].0, key1.deref());
assert_eq!(&*contents[0].1, b"cat");
assert_eq!(&*contents[1].0, key2.deref());
assert_eq!(&*contents[1].1, b"dog");
db.delete(&key1).unwrap();
assert!(db.get(&key1).unwrap().is_none());
db.put(&key1, b"cat").unwrap();
let transaction = DBTransaction::new();
transaction.put(&key3, b"elephant").unwrap();
transaction.delete(&key1).unwrap();
db.write(transaction).unwrap();
assert!(db.get(&key1).unwrap().is_none());
assert_eq!(db.get(&key3).unwrap().unwrap().deref(), b"elephant");
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if config.prefix_size.is_some() {
assert_eq!(db.get_by_prefix(&key3).unwrap().deref(), b"elephant");
assert_eq!(db.get_by_prefix(&key2).unwrap().deref(), b"dog");
}
}
#[test]
fn kvdb() {
let path = RandomTempPath::create_dir();
let smoke = Database::open_default(path.as_path().to_str().unwrap()).unwrap();
assert!(smoke.is_empty());
test_db(&DatabaseConfig { prefix_size: None });
test_db(&DatabaseConfig { prefix_size: Some(1) });
test_db(&DatabaseConfig { prefix_size: Some(8) });
test_db(&DatabaseConfig { prefix_size: Some(32) });
}
}