swarm: codebase split from go-ethereum (#1405)

state/dbstore.go

@@ -0,0 +1,111 @@
+// 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()
+}