97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
// Copyright 2014 by Sascha L. Teichmann
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// Use of this source code is governed by the MIT license
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// that can be found in the LICENSE file.
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package main
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import (
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leveldb "github.com/jmhodges/levigo"
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)
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type LevelDBBackend struct {
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cache *leveldb.Cache
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db *leveldb.DB
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tx *leveldb.WriteBatch
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}
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func NewLeveDBBackend(path string, cacheSize int) (ldb *LevelDBBackend, err error) {
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cache := leveldb.NewLRUCache(cacheSize * 1024 * 1024)
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opts := leveldb.NewOptions()
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opts.SetCache(cache)
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opts.SetCreateIfMissing(true)
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var db *leveldb.DB
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if db, err = leveldb.Open(path, opts); err != nil {
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cache.Close()
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return
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}
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ldb = &LevelDBBackend{
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cache: cache,
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db: db}
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return
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}
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func (ldb *LevelDBBackend) Shutdown() error {
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tx := ldb.tx
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if tx != nil {
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ldb.tx = nil
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tx.Close()
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}
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ldb.db.Close()
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ldb.cache.Close()
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return nil
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}
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func (ldb *LevelDBBackend) Fetch(hash, key []byte) ([]byte, error) {
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ro := leveldb.NewReadOptions()
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defer ro.Close()
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return ldb.db.Get(ro, key)
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}
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func (ldb *LevelDBBackend) InTransaction() bool {
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return ldb.tx != nil
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}
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func (ldb *LevelDBBackend) keyExists(key []byte) (exists bool, err error) {
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ro := leveldb.NewReadOptions()
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defer ro.Close()
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var data []byte
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if data, err = ldb.db.Get(ro, key); err != nil {
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return
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}
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exists = data != nil
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return
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}
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func (ldb *LevelDBBackend) Store(hash, key, value []byte) (exists bool, err error) {
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if exists, err = ldb.keyExists(key); err != nil {
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return
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}
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if ldb.tx != nil {
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ldb.tx.Put(key, value)
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return
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}
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wo := leveldb.NewWriteOptions()
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defer wo.Close()
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if err = ldb.db.Put(wo, key, value); err != nil {
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return
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}
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return
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}
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func (ldb *LevelDBBackend) BeginTransaction() error {
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ldb.tx = leveldb.NewWriteBatch()
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return nil
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}
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func (ldb *LevelDBBackend) CommitTransaction() error {
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tx := ldb.tx
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ldb.tx = nil
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wo := leveldb.NewWriteOptions()
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defer wo.Close()
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return ldb.db.Write(wo, tx)
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}
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