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// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus 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 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 library. If not, see
// <http://www.gnu.org/licenses/>.
package db
import (
"encoding/json"
"github.com/syndtr/goleveldb/leveldb"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/types"
)
// LevelDBBackedDB is a leveldb backed DB implementation.
type LevelDBBackedDB struct {
db *leveldb.DB
}
// NewLevelDBBackedDB initialize a leveldb-backed database.
func NewLevelDBBackedDB(
path string) (lvl *LevelDBBackedDB, err error) {
dbInst, err := leveldb.OpenFile(path, nil)
if err != nil {
return
}
lvl = &LevelDBBackedDB{db: dbInst}
return
}
// Close implement Closer interface, which would release allocated resource.
func (lvl *LevelDBBackedDB) Close() error {
return lvl.db.Close()
}
// HasBlock implements the Reader.Has method.
func (lvl *LevelDBBackedDB) HasBlock(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
}
// GetBlock implements the Reader.GetBlock method.
func (lvl *LevelDBBackedDB) GetBlock(
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
}
// UpdateBlock implements the Writer.UpdateBlock method.
func (lvl *LevelDBBackedDB) UpdateBlock(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.HasBlock(block.Hash) {
err = ErrBlockDoesNotExist
return
}
err = lvl.db.Put(
[]byte(block.Hash[:]),
marshaled,
nil)
if err != nil {
return
}
return
}
// PutBlock implements the Writer.PutBlock method.
func (lvl *LevelDBBackedDB) PutBlock(block types.Block) (err error) {
marshaled, err := json.Marshal(&block)
if err != nil {
return
}
if lvl.HasBlock(block.Hash) {
err = ErrBlockExists
return
}
err = lvl.db.Put(
[]byte(block.Hash[:]),
marshaled,
nil)
if err != nil {
return
}
return
}
// GetAllBlocks implements Reader.GetAllBlocks method, which allows callers
// to retrieve all blocks in DB.
func (lvl *LevelDBBackedDB) GetAllBlocks() (BlockIterator, error) {
// TODO (mission): Implement this part via goleveldb's iterator.
return nil, ErrNotImplemented
}
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