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author | Wei-Ning Huang <w@dexon.org> | 2018-09-17 17:45:49 +0800 |
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committer | GitHub <noreply@github.com> | 2018-09-17 17:45:49 +0800 |
commit | 8a908e98279d7e80978cd412057eddd4a6bbf06c (patch) | |
tree | 4e28f76fd95814978210c6f38ec4a09988e76957 /core/blockdb/memory.go | |
parent | cbf0012603deb6d2b8c257c079de98792f7b84cf (diff) | |
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core: move blockdb into core package and minor change on governance interface (#110)
Since third party apps will possibly implement their only blockdb class,
it make sense for the interface to be in core.
Also add GetNumShards into the governance interface.
Diffstat (limited to 'core/blockdb/memory.go')
-rw-r--r-- | core/blockdb/memory.go | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/core/blockdb/memory.go b/core/blockdb/memory.go new file mode 100644 index 0000000..eeda477 --- /dev/null +++ b/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 +} |