github.com/alanchchen/go-ethereum@v1.6.6-0.20170601190819-6171d01b1195/swarm/storage/localstore.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package storage
    18  
    19  import (
    20  	"encoding/binary"
    21  )
    22  
    23  // LocalStore is a combination of inmemory db over a disk persisted db
    24  // implements a Get/Put with fallback (caching) logic using any 2 ChunkStores
    25  type LocalStore struct {
    26  	memStore ChunkStore
    27  	DbStore  ChunkStore
    28  }
    29  
    30  // This constructor uses MemStore and DbStore as components
    31  func NewLocalStore(hash Hasher, params *StoreParams) (*LocalStore, error) {
    32  	dbStore, err := NewDbStore(params.ChunkDbPath, hash, params.DbCapacity, params.Radius)
    33  	if err != nil {
    34  		return nil, err
    35  	}
    36  	return &LocalStore{
    37  		memStore: NewMemStore(dbStore, params.CacheCapacity),
    38  		DbStore:  dbStore,
    39  	}, nil
    40  }
    41  
    42  // LocalStore is itself a chunk store
    43  // unsafe, in that the data is not integrity checked
    44  func (self *LocalStore) Put(chunk *Chunk) {
    45  	chunk.dbStored = make(chan bool)
    46  	self.memStore.Put(chunk)
    47  	if chunk.wg != nil {
    48  		chunk.wg.Add(1)
    49  	}
    50  	go func() {
    51  		self.DbStore.Put(chunk)
    52  		if chunk.wg != nil {
    53  			chunk.wg.Done()
    54  		}
    55  	}()
    56  }
    57  
    58  // Get(chunk *Chunk) looks up a chunk in the local stores
    59  // This method is blocking until the chunk is retrieved
    60  // so additional timeout may be needed to wrap this call if
    61  // ChunkStores are remote and can have long latency
    62  func (self *LocalStore) Get(key Key) (chunk *Chunk, err error) {
    63  	chunk, err = self.memStore.Get(key)
    64  	if err == nil {
    65  		return
    66  	}
    67  	chunk, err = self.DbStore.Get(key)
    68  	if err != nil {
    69  		return
    70  	}
    71  	chunk.Size = int64(binary.LittleEndian.Uint64(chunk.SData[0:8]))
    72  	self.memStore.Put(chunk)
    73  	return
    74  }
    75  
    76  // Close local store
    77  func (self *LocalStore) Close() {
    78  	return
    79  }