github.com/oskarth/go-ethereum@v1.6.8-0.20191013093314-dac24a9d3494/swarm/state/dbstore.go (about) 1 // Copyright 2018 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package state 18 19 import ( 20 "encoding" 21 "encoding/json" 22 "errors" 23 24 "github.com/syndtr/goleveldb/leveldb" 25 ) 26 27 // ErrNotFound is returned when no results are returned from the database 28 var ErrNotFound = errors.New("ErrorNotFound") 29 30 // ErrInvalidArgument is returned when the argument type does not match the expected type 31 var ErrInvalidArgument = errors.New("ErrorInvalidArgument") 32 33 // DBStore uses LevelDB to store values. 34 type DBStore struct { 35 db *leveldb.DB 36 } 37 38 // NewDBStore creates a new instance of DBStore. 39 func NewDBStore(path string) (s *DBStore, err error) { 40 db, err := leveldb.OpenFile(path, nil) 41 if err != nil { 42 return nil, err 43 } 44 return &DBStore{ 45 db: db, 46 }, nil 47 } 48 49 // Get retrieves a persisted value for a specific key. If there is no results 50 // ErrNotFound is returned. The provided parameter should be either a byte slice or 51 // a struct that implements the encoding.BinaryUnmarshaler interface 52 func (s *DBStore) Get(key string, i interface{}) (err error) { 53 has, err := s.db.Has([]byte(key), nil) 54 if err != nil || !has { 55 return ErrNotFound 56 } 57 58 data, err := s.db.Get([]byte(key), nil) 59 if err == leveldb.ErrNotFound { 60 return ErrNotFound 61 } 62 63 unmarshaler, ok := i.(encoding.BinaryUnmarshaler) 64 if !ok { 65 return json.Unmarshal(data, i) 66 } 67 return unmarshaler.UnmarshalBinary(data) 68 } 69 70 // Put stores an object that implements Binary for a specific key. 71 func (s *DBStore) Put(key string, i interface{}) (err error) { 72 bytes := []byte{} 73 74 marshaler, ok := i.(encoding.BinaryMarshaler) 75 if !ok { 76 if bytes, err = json.Marshal(i); err != nil { 77 return err 78 } 79 } else { 80 if bytes, err = marshaler.MarshalBinary(); err != nil { 81 return err 82 } 83 } 84 85 return s.db.Put([]byte(key), bytes, nil) 86 } 87 88 // Delete removes entries stored under a specific key. 89 func (s *DBStore) Delete(key string) (err error) { 90 return s.db.Delete([]byte(key), nil) 91 } 92 93 // Close releases the resources used by the underlying LevelDB. 94 func (s *DBStore) Close() error { 95 return s.db.Close() 96 }