1 files changed, 185 insertions, 0 deletions
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/db/memory.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/db/memory.go
new file mode 100644
index 000000000..4246e4fe1
--- /dev/null
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/db/memory.go
@@ -0,0 +1,185 @@
+// 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"
+	"io/ioutil"
+	"os"
+	"sync"
+
+	"github.com/dexon-foundation/dexon-consensus/common"
+	"github.com/dexon-foundation/dexon-consensus/core/types"
+)
+
+type blockSeqIterator struct {
+	idx int
+	db  *MemBackedDB
+}
+
+// NextBlock implemenets BlockIterator.NextBlock method.
+func (seq *blockSeqIterator) NextBlock() (types.Block, error) {
+	curIdx := seq.idx
+	seq.idx++
+	return seq.db.getBlockByIndex(curIdx)
+}
+
+// MemBackedDB is a memory backed DB implementation.
+type MemBackedDB struct {
+	blocksMutex        sync.RWMutex
+	blockHashSequence  common.Hashes
+	blocksByHash       map[common.Hash]*types.Block
+	persistantFilePath string
+}
+
+// NewMemBackedDB initialize a memory-backed database.
+func NewMemBackedDB(persistantFilePath ...string) (
+	dbInst *MemBackedDB, err error) {
+	dbInst = &MemBackedDB{
+		blockHashSequence: common.Hashes{},
+		blocksByHash:      make(map[common.Hash]*types.Block),
+	}
+	if len(persistantFilePath) == 0 || len(persistantFilePath[0]) == 0 {
+		return
+	}
+	dbInst.persistantFilePath = persistantFilePath[0]
+	buf, err := ioutil.ReadFile(dbInst.persistantFilePath)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			// Something unexpected happened.
+			return
+		}
+		// It's expected behavior that file doesn't exists, we should not
+		// report error on it.
+		err = nil
+		return
+	}
+
+	// Init this instance by file content, it's a temporary way
+	// to export those private field for JSON encoding.
+	toLoad := struct {
+		Sequence common.Hashes
+		ByHash   map[common.Hash]*types.Block
+	}{}
+	err = json.Unmarshal(buf, &toLoad)
+	if err != nil {
+		return
+	}
+	dbInst.blockHashSequence = toLoad.Sequence
+	dbInst.blocksByHash = toLoad.ByHash
+	return
+}
+
+// HasBlock returns wheter or not the DB has a block identified with the hash.
+func (m *MemBackedDB) HasBlock(hash common.Hash) bool {
+	m.blocksMutex.RLock()
+	defer m.blocksMutex.RUnlock()
+
+	_, ok := m.blocksByHash[hash]
+	return ok
+}
+
+// GetBlock returns a block given a hash.
+func (m *MemBackedDB) GetBlock(hash common.Hash) (types.Block, error) {
+	m.blocksMutex.RLock()
+	defer m.blocksMutex.RUnlock()
+
+	return m.internalGetBlock(hash)
+}
+
+func (m *MemBackedDB) internalGetBlock(hash common.Hash) (types.Block, error) {
+	b, ok := m.blocksByHash[hash]
+	if !ok {
+		return types.Block{}, ErrBlockDoesNotExist
+	}
+	return *b, nil
+}
+
+// PutBlock inserts a new block into the database.
+func (m *MemBackedDB) PutBlock(block types.Block) error {
+	if m.HasBlock(block.Hash) {
+		return ErrBlockExists
+	}
+
+	m.blocksMutex.Lock()
+	defer m.blocksMutex.Unlock()
+
+	m.blockHashSequence = append(m.blockHashSequence, block.Hash)
+	m.blocksByHash[block.Hash] = &block
+	return nil
+}
+
+// UpdateBlock updates a block in the database.
+func (m *MemBackedDB) UpdateBlock(block types.Block) error {
+	if !m.HasBlock(block.Hash) {
+		return ErrBlockDoesNotExist
+	}
+
+	m.blocksMutex.Lock()
+	defer m.blocksMutex.Unlock()
+
+	m.blocksByHash[block.Hash] = &block
+	return nil
+}
+
+// Close implement Closer interface, which would release allocated resource.
+func (m *MemBackedDB) Close() (err error) {
+	// Save internal state to a pretty-print json file. It's a temporary way
+	// to dump private file via JSON encoding.
+	if len(m.persistantFilePath) == 0 {
+		return
+	}
+
+	m.blocksMutex.RLock()
+	defer m.blocksMutex.RUnlock()
+
+	toDump := struct {
+		Sequence common.Hashes
+		ByHash   map[common.Hash]*types.Block
+	}{
+		Sequence: m.blockHashSequence,
+		ByHash:   m.blocksByHash,
+	}
+
+	// Dump to JSON with 2-space indent.
+	buf, err := json.Marshal(&toDump)
+	if err != nil {
+		return
+	}
+
+	err = ioutil.WriteFile(m.persistantFilePath, buf, 0644)
+	return
+}
+
+func (m *MemBackedDB) getBlockByIndex(idx int) (types.Block, error) {
+	m.blocksMutex.RLock()
+	defer m.blocksMutex.RUnlock()
+
+	if idx >= len(m.blockHashSequence) {
+		return types.Block{}, ErrIterationFinished
+	}
+
+	hash := m.blockHashSequence[idx]
+	return m.internalGetBlock(hash)
+}
+
+// GetAllBlocks implement Reader.GetAllBlocks method, which allows caller
+// to retrieve all blocks in DB.
+func (m *MemBackedDB) GetAllBlocks() (BlockIterator, error) {
+	return &blockSeqIterator{db: m}, nil
+}