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// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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 dexon-consensus-core 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 dexon-consensus-core library. If not, see
// <http://www.gnu.org/licenses/>.
package blockdb
import (
"encoding/json"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
)
// LevelDBBackedBlockDB is a leveldb backed BlockDB implementation.
type LevelDBBackedBlockDB struct {
db *leveldb.DB
}
// NewLevelDBBackedBlockDB initialize a leveldb-backed block database.
func NewLevelDBBackedBlockDB(
path string) (lvl *LevelDBBackedBlockDB, err error) {
db, err := leveldb.OpenFile(path, nil)
if err != nil {
return
}
lvl = &LevelDBBackedBlockDB{db: db}
return
}
// Close implement Closer interface, which would release allocated resource.
func (lvl *LevelDBBackedBlockDB) Close() error {
return lvl.db.Close()
}
// Has implements the Reader.Has method.
func (lvl *LevelDBBackedBlockDB) Has(hash common.Hash) bool {
exists, err := lvl.db.Has([]byte(hash[:]), nil)
if err != nil {
// TODO(missionliao): Modify the interface to return error.
panic(err)
}
return exists
}
// Get implements the Reader.Get method.
func (lvl *LevelDBBackedBlockDB) Get(
hash common.Hash) (block types.Block, err error) {
queried, err := lvl.db.Get([]byte(hash[:]), nil)
if err != nil {
if err == leveldb.ErrNotFound {
err = ErrBlockDoesNotExist
}
return
}
err = json.Unmarshal(queried, &block)
if err != nil {
return
}
return
}
// Update implements the Writer.Update method.
func (lvl *LevelDBBackedBlockDB) Update(block types.Block) (err error) {
// NOTE: we didn't handle changes of block hash (and it
// should not happen).
marshaled, err := json.Marshal(&block)
if err != nil {
return
}
if !lvl.Has(block.Hash) {
err = ErrBlockDoesNotExist
return
}
err = lvl.db.Put(
[]byte(block.Hash[:]),
marshaled,
&opt.WriteOptions{
Sync: true,
})
if err != nil {
return
}
return
}
// Put implements the Writer.Put method.
func (lvl *LevelDBBackedBlockDB) Put(block types.Block) (err error) {
marshaled, err := json.Marshal(&block)
if err != nil {
return
}
if lvl.Has(block.Hash) {
err = ErrBlockExists
return
}
syncedOpt := &opt.WriteOptions{
// We should force to sync for each write, it's safer
// from crash.
Sync: true,
}
err = lvl.db.Put(
[]byte(block.Hash[:]),
marshaled,
syncedOpt)
if err != nil {
return
}
return
}
// GetAll implements Reader.GetAll method, which allows callers
// to retrieve all blocks in DB.
func (lvl *LevelDBBackedBlockDB) GetAll() (BlockIterator, error) {
// TODO (mission): Implement this part via goleveldb's iterator.
return nil, ErrNotImplemented
}
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