path: root/swarm/storage/mock/db/db.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package db implements a mock store that keeps all chunk data in LevelDB database.
package db

import (
    "archive/tar"
    "bytes"
    "encoding/json"
    "io"
    "io/ioutil"

    "github.com/syndtr/goleveldb/leveldb"
    "github.com/syndtr/goleveldb/leveldb/util"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/swarm/storage/mock"
)

// GlobalStore contains the LevelDB database that is storing
// chunk data for all swarm nodes.
// Closing the GlobalStore with Close method is required to
// release resources used by the database.
type GlobalStore struct {
    db *leveldb.DB
}

// NewGlobalStore creates a new instance of GlobalStore.
func NewGlobalStore(path string) (s *GlobalStore, err error) {
    db, err := leveldb.OpenFile(path, nil)
    if err != nil {
        return nil, err
    }
    return &GlobalStore{
        db: db,
    }, nil
}

// Close releases the resources used by the underlying LevelDB.
func (s *GlobalStore) Close() error {
    return s.db.Close()
}

// NewNodeStore returns a new instance of NodeStore that retrieves and stores
// chunk data only for a node with address addr.
func (s *GlobalStore) NewNodeStore(addr common.Address) *mock.NodeStore {
    return mock.NewNodeStore(addr, s)
}

// Get returns chunk data if the chunk with key exists for node
// on address addr.
func (s *GlobalStore) Get(addr common.Address, key []byte) (data []byte, err error) {
    has, err := s.db.Has(nodeDBKey(addr, key), nil)
    if err != nil {
        return nil, mock.ErrNotFound
    }
    if !has {
        return nil, mock.ErrNotFound
    }
    data, err = s.db.Get(dataDBKey(key), nil)
    if err == leveldb.ErrNotFound {
        err = mock.ErrNotFound
    }
    return
}

// Put saves the chunk data for node with address addr.
func (s *GlobalStore) Put(addr common.Address, key []byte, data []byte) error {
    batch := new(leveldb.Batch)
    batch.Put(nodeDBKey(addr, key), nil)
    batch.Put(dataDBKey(key), data)
    return s.db.Write(batch, nil)
}

// Delete removes the chunk reference to node with address addr.
func (s *GlobalStore) Delete(addr common.Address, key []byte) error {
    batch := new(leveldb.Batch)
    batch.Delete(nodeDBKey(addr, key))
    return s.db.Write(batch, nil)
}

// HasKey returns whether a node with addr contains the key.
func (s *GlobalStore) HasKey(addr common.Address, key []byte) bool {
    has, err := s.db.Has(nodeDBKey(addr, key), nil)
    if err != nil {
        has = false
    }
    return has
}

// Import reads tar archive from a reader that contains exported chunk data.
// It returns the number of chunks imported and an error.
func (s *GlobalStore) Import(r io.Reader) (n int, err error) {
    tr := tar.NewReader(r)

    for {
        hdr, err := tr.Next()
        if err != nil {
            if err == io.EOF {
                break
            }
            return n, err
        }

        data, err := ioutil.ReadAll(tr)
        if err != nil {
            return n, err
        }

        var c mock.ExportedChunk
        if err = json.Unmarshal(data, &c); err != nil {
            return n, err
        }

        batch := new(leveldb.Batch)
        for _, addr := range c.Addrs {
            batch.Put(nodeDBKeyHex(addr, hdr.Name), nil)
        }

        batch.Put(dataDBKey(common.Hex2Bytes(hdr.Name)), c.Data)
        if err = s.db.Write(batch, nil); err != nil {
            return n, err
        }

        n++
    }
    return n, err
}

// Export writes to a writer a tar archive with all chunk data from
// the store. It returns the number fo chunks exported and an error.
func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
    tw := tar.NewWriter(w)
    defer tw.Close()

    buf := bytes.NewBuffer(make([]byte, 0, 1024))
    encoder := json.NewEncoder(buf)

    iter := s.db.NewIterator(util.BytesPrefix(nodeKeyPrefix), nil)
    defer iter.Release()

    var currentKey string
    var addrs []common.Address

    saveChunk := func(hexKey string) error {
        key := common.Hex2Bytes(hexKey)

        data, err := s.db.Get(dataDBKey(key), nil)
        if err != nil {
            return err
        }

        buf.Reset()
        if err = encoder.Encode(mock.ExportedChunk{
            Addrs: addrs,
            Data:  data,
        }); err != nil {
            return err
        }

        d := buf.Bytes()
        hdr := &tar.Header{
            Name: hexKey,
            Mode: 0644,
            Size: int64(len(d)),
        }
        if err := tw.WriteHeader(hdr); err != nil {
            return err
        }
        if _, err := tw.Write(d); err != nil {
            return err
        }
        n++
        return nil
    }

    for iter.Next() {
        k := bytes.TrimPrefix(iter.Key(), nodeKeyPrefix)
        i := bytes.Index(k, []byte("-"))
        if i < 0 {
            continue
        }
        hexKey := string(k[:i])

        if currentKey == "" {
            currentKey = hexKey
        }

        if hexKey != currentKey {
            if err = saveChunk(currentKey); err != nil {
                return n, err
            }

            addrs = addrs[:0]
        }

        currentKey = hexKey
        addrs = append(addrs, common.BytesToAddress(k[i:]))
    }

    if len(addrs) > 0 {
        if err = saveChunk(currentKey); err != nil {
            return n, err
        }
    }

    return n, err
}

var (
    nodeKeyPrefix = []byte("node-")
    dataKeyPrefix = []byte("data-")
)

// nodeDBKey constructs a database key for key/node mappings.
func nodeDBKey(addr common.Address, key []byte) []byte {
    return nodeDBKeyHex(addr, common.Bytes2Hex(key))
}

// nodeDBKeyHex constructs a database key for key/node mappings
// using the hexadecimal string representation of the key.
func nodeDBKeyHex(addr common.Address, hexKey string) []byte {
    return append(append(nodeKeyPrefix, []byte(hexKey+"-")...), addr[:]...)
}

// dataDBkey constructs a database key for key/data storage.
func dataDBKey(key []byte) []byte {
    return append(dataKeyPrefix, key...)
}