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// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package storage
import (
"encoding/binary"
)
// LocalStore is a combination of inmemory db over a disk persisted db
// implements a Get/Put with fallback (caching) logic using any 2 ChunkStores
type LocalStore struct {
memStore ChunkStore
DbStore ChunkStore
}
// This constructor uses MemStore and DbStore as components
func NewLocalStore(hash Hasher, params *StoreParams) (*LocalStore, error) {
dbStore, err := NewDbStore(params.ChunkDbPath, hash, params.DbCapacity, params.Radius)
if err != nil {
return nil, err
}
return &LocalStore{
memStore: NewMemStore(dbStore, params.CacheCapacity),
DbStore: dbStore,
}, nil
}
// LocalStore is itself a chunk store
// unsafe, in that the data is not integrity checked
func (self *LocalStore) Put(chunk *Chunk) {
chunk.dbStored = make(chan bool)
self.memStore.Put(chunk)
if chunk.wg != nil {
chunk.wg.Add(1)
}
go func() {
self.DbStore.Put(chunk)
if chunk.wg != nil {
chunk.wg.Done()
}
}()
}
// Get(chunk *Chunk) looks up a chunk in the local stores
// This method is blocking until the chunk is retrieved
// so additional timeout may be needed to wrap this call if
// ChunkStores are remote and can have long latency
func (self *LocalStore) Get(key Key) (chunk *Chunk, err error) {
chunk, err = self.memStore.Get(key)
if err == nil {
return
}
chunk, err = self.DbStore.Get(key)
if err != nil {
return
}
chunk.Size = int64(binary.LittleEndian.Uint64(chunk.SData[0:8]))
self.memStore.Put(chunk)
return
}
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