path: root/core/db/level-db.go

// 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/binary"

    "github.com/syndtr/goleveldb/leveldb"

    "github.com/dexon-foundation/dexon-consensus/common"
    "github.com/dexon-foundation/dexon-consensus/core/crypto/dkg"
    "github.com/dexon-foundation/dexon-consensus/core/types"
    "github.com/dexon-foundation/dexon/rlp"
)

var (
    blockKeyPrefix            = []byte("b-")
    compactionChainTipInfoKey = []byte("cc-tip")
    dkgPrivateKeyKeyPrefix    = []byte("dkg-prvs")
)

type compactionChainTipInfo struct {
    Height uint64      `json:"height"`
    Hash   common.Hash `json:"hash"`
}

// 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.internalHasBlock(lvl.getBlockKey(hash))
    if err != nil {
        // TODO(missionliao): Modify the interface to return error.
        panic(err)
    }
    return exists
}

func (lvl *LevelDBBackedDB) internalHasBlock(key []byte) (bool, error) {
    exists, err := lvl.db.Has(key, nil)
    if err != nil {
        return false, err
    }
    return exists, nil
}

// GetBlock implements the Reader.GetBlock method.
func (lvl *LevelDBBackedDB) GetBlock(
    hash common.Hash) (block types.Block, err error) {
    queried, err := lvl.db.Get(lvl.getBlockKey(hash), nil)
    if err != nil {
        if err == leveldb.ErrNotFound {
            err = ErrBlockDoesNotExist
        }
        return
    }
    err = rlp.DecodeBytes(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 := rlp.EncodeToBytes(&block)
    if err != nil {
        return
    }
    blockKey := lvl.getBlockKey(block.Hash)
    exists, err := lvl.internalHasBlock(blockKey)
    if err != nil {
        return
    }
    if !exists {
        err = ErrBlockDoesNotExist
        return
    }
    if err = lvl.db.Put(blockKey, marshaled, nil); err != nil {
        return
    }
    return
}

// PutBlock implements the Writer.PutBlock method.
func (lvl *LevelDBBackedDB) PutBlock(block types.Block) (err error) {
    marshaled, err := rlp.EncodeToBytes(&block)
    if err != nil {
        return
    }
    blockKey := lvl.getBlockKey(block.Hash)
    exists, err := lvl.internalHasBlock(blockKey)
    if err != nil {
        return
    }
    if exists {
        err = ErrBlockExists
        return
    }
    if err = lvl.db.Put(blockKey, marshaled, nil); 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
}

// PutCompactionChainTipInfo saves tip of compaction chain into the database.
func (lvl *LevelDBBackedDB) PutCompactionChainTipInfo(
    blockHash common.Hash, height uint64) error {
    marshaled, err := rlp.EncodeToBytes(&compactionChainTipInfo{
        Hash:   blockHash,
        Height: height,
    })
    if err != nil {
        return err
    }
    // Check current cached tip info to make sure the one to be updated is
    // valid.
    info, err := lvl.internalGetCompactionChainTipInfo()
    if err != nil {
        return err
    }
    if info.Height+1 != height {
        return ErrInvalidCompactionChainTipHeight
    }
    if err = lvl.db.Put(compactionChainTipInfoKey, marshaled, nil); err != nil {
        return err
    }
    return nil
}

func (lvl *LevelDBBackedDB) internalGetCompactionChainTipInfo() (
    info compactionChainTipInfo, err error) {
    queried, err := lvl.db.Get(compactionChainTipInfoKey, nil)
    if err != nil {
        if err == leveldb.ErrNotFound {
            err = nil
        }
        return
    }
    if err = rlp.DecodeBytes(queried, &info); err != nil {
        return
    }
    return
}

// GetCompactionChainTipInfo get the tip info of compaction chain into the
// database.
func (lvl *LevelDBBackedDB) GetCompactionChainTipInfo() (
    hash common.Hash, height uint64) {
    info, err := lvl.internalGetCompactionChainTipInfo()
    if err != nil {
        panic(err)
    }
    hash, height = info.Hash, info.Height
    return
}

// HasDKGPrivateKey check existence of DKG private key of one round.
func (lvl *LevelDBBackedDB) HasDKGPrivateKey(round uint64) (bool, error) {
    exists, err := lvl.db.Has(lvl.getDKGPrivateKeyKey(round), nil)
    if err != nil {
        return false, err
    }
    return exists, nil
}

// GetDKGPrivateKey get DKG private key of one round.
func (lvl *LevelDBBackedDB) GetDKGPrivateKey(round uint64) (
    prv dkg.PrivateKey, err error) {
    queried, err := lvl.db.Get(lvl.getDKGPrivateKeyKey(round), nil)
    if err != nil {
        if err == leveldb.ErrNotFound {
            err = ErrDKGPrivateKeyDoesNotExist
        }
        return
    }
    if err = rlp.DecodeBytes(queried, &prv); err != nil {
        return
    }
    return
}

// PutDKGPrivateKey save DKG private key of one round.
func (lvl *LevelDBBackedDB) PutDKGPrivateKey(
    round uint64, prv dkg.PrivateKey) error {
    // Check existence.
    exists, err := lvl.HasDKGPrivateKey(round)
    if err != nil {
        return err
    }
    if exists {
        return ErrDKGPrivateKeyExists
    }
    marshaled, err := rlp.EncodeToBytes(&prv)
    if err != nil {
        return err
    }
    if err := lvl.db.Put(
        lvl.getDKGPrivateKeyKey(round), marshaled, nil); err != nil {
        return err
    }
    return nil
}

func (lvl *LevelDBBackedDB) getBlockKey(hash common.Hash) (ret []byte) {
    ret = make([]byte, len(blockKeyPrefix)+len(hash[:]))
    copy(ret, blockKeyPrefix)
    copy(ret[len(blockKeyPrefix):], hash[:])
    return
}

func (lvl *LevelDBBackedDB) getDKGPrivateKeyKey(
    round uint64) (ret []byte) {
    ret = make([]byte, len(dkgPrivateKeyKeyPrefix)+8)
    copy(ret, dkgPrivateKeyKeyPrefix)
    binary.LittleEndian.PutUint64(
        ret[len(dkgPrivateKeyKeyPrefix):], round)
    return
}