path: root/trie/cache.go

package trie

import (
    "github.com/ethereum/go-ethereum/compression/rle"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/syndtr/goleveldb/leveldb"
)

type Backend interface {
    Get([]byte) ([]byte, error)
    Put([]byte, []byte) error
}

type Cache struct {
    batch   *leveldb.Batch
    store   map[string][]byte
    backend Backend
}

func NewCache(backend Backend) *Cache {
    return &Cache{new(leveldb.Batch), make(map[string][]byte), backend}
}

func (self *Cache) Get(key []byte) []byte {
    data := self.store[string(key)]
    if data == nil {
        data, _ = self.backend.Get(key)
    }

    return data
}

func (self *Cache) Put(key []byte, data []byte) {
    // write the data to the ldb batch
    self.batch.Put(key, rle.Compress(data))
    self.store[string(key)] = data
}

// Flush flushes the trie to the backing layer. If this is a leveldb instance
// we'll use a batched write, otherwise we'll use regular put.
func (self *Cache) Flush() {
    if db, ok := self.backend.(*ethdb.LDBDatabase); ok {
        if err := db.LDB().Write(self.batch, nil); err != nil {
            glog.Fatal("db write err:", err)
        }
    } else {
        for k, v := range self.store {
            self.backend.Put([]byte(k), v)
        }
    }
}

func (self *Cache) Copy() *Cache {
    cache := NewCache(self.backend)
    for k, v := range self.store {
        cache.store[k] = v
    }
    return cache
}

func (self *Cache) Reset() {
    //self.store = make(map[string][]byte)
}