diff options
Diffstat (limited to 'vendor/github.com/dexon-foundation/dexon-consensus-core/core/blockdb/memory.go')
-rw-r--r-- | vendor/github.com/dexon-foundation/dexon-consensus-core/core/blockdb/memory.go | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus-core/core/blockdb/memory.go b/vendor/github.com/dexon-foundation/dexon-consensus-core/core/blockdb/memory.go new file mode 100644 index 000000000..eeda47772 --- /dev/null +++ b/vendor/github.com/dexon-foundation/dexon-consensus-core/core/blockdb/memory.go @@ -0,0 +1,179 @@ +// 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" + "io/ioutil" + "os" + "sync" + + "github.com/dexon-foundation/dexon-consensus-core/common" + "github.com/dexon-foundation/dexon-consensus-core/core/types" +) + +type seqIterator struct { + idx int + db *MemBackedBlockDB +} + +func (seq *seqIterator) Next() (types.Block, error) { + curIdx := seq.idx + seq.idx++ + return seq.db.getByIndex(curIdx) +} + +// MemBackedBlockDB is a memory backed BlockDB implementation. +type MemBackedBlockDB struct { + blocksMutex sync.RWMutex + blockHashSequence common.Hashes + blocksByHash map[common.Hash]*types.Block + persistantFilePath string +} + +// NewMemBackedBlockDB initialize a memory-backed block database. +func NewMemBackedBlockDB(persistantFilePath ...string) (db *MemBackedBlockDB, err error) { + db = &MemBackedBlockDB{ + blockHashSequence: common.Hashes{}, + blocksByHash: make(map[common.Hash]*types.Block), + } + if len(persistantFilePath) == 0 || len(persistantFilePath[0]) == 0 { + return + } + db.persistantFilePath = persistantFilePath[0] + buf, err := ioutil.ReadFile(db.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 + } + db.blockHashSequence = toLoad.Sequence + db.blocksByHash = toLoad.ByHash + return +} + +// Has returns wheter or not the DB has a block identified with the hash. +func (m *MemBackedBlockDB) Has(hash common.Hash) bool { + m.blocksMutex.RLock() + defer m.blocksMutex.RUnlock() + + _, ok := m.blocksByHash[hash] + return ok +} + +// Get returns a block given a hash. +func (m *MemBackedBlockDB) Get(hash common.Hash) (types.Block, error) { + m.blocksMutex.RLock() + defer m.blocksMutex.RUnlock() + + return m.internalGet(hash) +} + +func (m *MemBackedBlockDB) internalGet(hash common.Hash) (types.Block, error) { + b, ok := m.blocksByHash[hash] + if !ok { + return types.Block{}, ErrBlockDoesNotExist + } + return *b, nil +} + +// Put inserts a new block into the database. +func (m *MemBackedBlockDB) Put(block types.Block) error { + if m.Has(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 +} + +// Update updates a block in the database. +func (m *MemBackedBlockDB) Update(block types.Block) error { + 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 *MemBackedBlockDB) 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 *MemBackedBlockDB) getByIndex(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.internalGet(hash) +} + +// GetAll implement Reader.GetAll method, which allows caller +// to retrieve all blocks in DB. +func (m *MemBackedBlockDB) GetAll() (BlockIterator, error) { + return &seqIterator{db: m}, nil +} |