Implement blockdb levelDB backend (#6)

1 files changed, 213 insertions, 0 deletions

diff --git a/blockdb/level-db.go b/blockdb/level-db.go
new file mode 100644
index 0000000..c6d0a7b
--- /dev/null
+++ b/blockdb/level-db.go
@@ -0,0 +1,213 @@
+// 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"
+	"sync"
+
+	"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"
+)
+
+// LevelDBBackendBlockDB is a leveldb backend BlockDB implementation.
+type LevelDBBackendBlockDB struct {
+	db        *leveldb.DB
+	index     map[types.ValidatorID]map[uint64]common.Hash
+	indexLock sync.RWMutex
+}
+
+// NewLevelDBBackendBlockDB initialize a leveldb-backed block database.
+func NewLevelDBBackendBlockDB(
+	path string) (lvl *LevelDBBackendBlockDB, err error) {
+
+	db, err := leveldb.OpenFile(path, nil)
+	if err != nil {
+		return
+	}
+	lvl = &LevelDBBackendBlockDB{db: db}
+	err = lvl.syncIndex()
+	if err != nil {
+		return
+	}
+	return
+}
+
+// Close would release allocated resource.
+func (lvl *LevelDBBackendBlockDB) Close() error {
+	return lvl.db.Close()
+}
+
+// Has implements the Reader.Has method.
+func (lvl *LevelDBBackendBlockDB) 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 *LevelDBBackendBlockDB) 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
+}
+
+// GetByValidatorAndHeight implements
+// the Reader.GetByValidatorAndHeight method.
+func (lvl *LevelDBBackendBlockDB) GetByValidatorAndHeight(
+	vID types.ValidatorID, height uint64) (block types.Block, err error) {
+
+	lvl.indexLock.RLock()
+	defer lvl.indexLock.RUnlock()
+
+	// Get block's hash from in-memory index.
+	vMap, exists := lvl.index[vID]
+	if !exists {
+		err = ErrBlockDoesNotExist
+		return
+	}
+	hash, exists := vMap[height]
+	if !exists {
+		err = ErrBlockDoesNotExist
+		return
+	}
+
+	// Get block from hash.
+	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 *LevelDBBackendBlockDB) 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 *LevelDBBackendBlockDB) 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
+	}
+
+	// Build in-memory index.
+	lvl.addIndex(&block)
+	return
+}
+
+func (lvl *LevelDBBackendBlockDB) syncIndex() (err error) {
+	// Reset index.
+	lvl.index = make(map[types.ValidatorID]map[uint64]common.Hash)
+
+	// Construct index from DB.
+	iter := lvl.db.NewIterator(nil, nil)
+	defer func() {
+		iter.Release()
+		if err == nil {
+			// Only return iterator's error when no error
+			// is presented so far.
+			err = iter.Error()
+		}
+	}()
+
+	// Build index from blocks in DB, it may take time.
+	var block types.Block
+	for iter.Next() {
+		err = json.Unmarshal(iter.Value(), &block)
+		if err != nil {
+			return
+		}
+		lvl.addIndex(&block)
+	}
+	return
+}
+
+func (lvl *LevelDBBackendBlockDB) addIndex(block *types.Block) {
+	lvl.indexLock.Lock()
+	defer lvl.indexLock.Unlock()
+
+	heightMap, exists := lvl.index[block.ProposerID]
+	if !exists {
+		heightMap = make(map[uint64]common.Hash)
+		lvl.index[block.ProposerID] = heightMap
+	}
+	heightMap[block.Height] = block.Hash
+}