path: root/swarm/state/dbstore.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 state

import (
    "encoding"
    "encoding/json"
    "errors"

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

// ErrNotFound is returned when no results are returned from the database
var ErrNotFound = errors.New("ErrorNotFound")

// ErrInvalidArgument is returned when the argument type does not match the expected type
var ErrInvalidArgument = errors.New("ErrorInvalidArgument")

// DBStore uses LevelDB to store values.
type DBStore struct {
    db *leveldb.DB
}

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

// Get retrieves a persisted value for a specific key. If there is no results
// ErrNotFound is returned. The provided parameter should be either a byte slice or
// a struct that implements the encoding.BinaryUnmarshaler interface
func (s *DBStore) Get(key string, i interface{}) (err error) {
    has, err := s.db.Has([]byte(key), nil)
    if err != nil || !has {
        return ErrNotFound
    }

    data, err := s.db.Get([]byte(key), nil)
    if err == leveldb.ErrNotFound {
        return ErrNotFound
    }

    unmarshaler, ok := i.(encoding.BinaryUnmarshaler)
    if !ok {
        return json.Unmarshal(data, i)
    }
    return unmarshaler.UnmarshalBinary(data)
}

// Put stores an object that implements Binary for a specific key.
func (s *DBStore) Put(key string, i interface{}) (err error) {
    bytes := []byte{}

    marshaler, ok := i.(encoding.BinaryMarshaler)
    if !ok {
        if bytes, err = json.Marshal(i); err != nil {
            return err
        }
    } else {
        if bytes, err = marshaler.MarshalBinary(); err != nil {
            return err
        }
    }

    return s.db.Put([]byte(key), bytes, nil)
}

// Delete removes entries stored under a specific key.
func (s *DBStore) Delete(key string) (err error) {
    return s.db.Delete([]byte(key), nil)
}

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