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// 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"
"github.com/syndtr/goleveldb/leveldb/storage"
)
// ErrNotFound is returned when no results are returned from the database
var ErrNotFound = errors.New("ErrorNotFound")
// Store defines methods required to get, set, delete values for different keys
// and close the underlying resources.
type Store interface {
Get(key string, i interface{}) (err error)
Put(key string, i interface{}) (err error)
Delete(key string) (err error)
Close() error
}
// 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
}
// NewInmemoryStore returns a new instance of DBStore. To be used only in tests and simulations.
func NewInmemoryStore() *DBStore {
db, err := leveldb.Open(storage.NewMemStorage(), nil)
if err != nil {
panic(err)
}
return &DBStore{
db: db,
}
}
// 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) {
var bytes []byte
if marshaler, ok := i.(encoding.BinaryMarshaler); ok {
if bytes, err = marshaler.MarshalBinary(); err != nil {
return err
}
} else {
if bytes, err = json.Marshal(i); 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()
}
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