github.com/aigarnetwork/aigar@v0.0.0-20191115204914-d59a6eb70f8e/signer/storage/storage.go (about)

     1  //  Copyright 2018 The go-ethereum Authors
     2  //  Copyright 2019 The go-aigar Authors
     3  //  This file is part of the go-aigar library.
     4  //
     5  //  The go-aigar library is free software: you can redistribute it and/or modify
     6  //  it under the terms of the GNU Lesser General Public License as published by
     7  //  the Free Software Foundation, either version 3 of the License, or
     8  //  (at your option) any later version.
     9  //
    10  //  The go-aigar library is distributed in the hope that it will be useful,
    11  //  but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  //  GNU Lesser General Public License for more details.
    14  //
    15  //  You should have received a copy of the GNU Lesser General Public License
    16  //  along with the go-aigar library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package storage
    19  
    20  import "errors"
    21  
    22  var (
    23  	// ErrZeroKey is returned if an attempt was made to inset a 0-length key.
    24  	ErrZeroKey = errors.New("0-length key")
    25  
    26  	// ErrNotFound is returned if an unknown key is attempted to be retrieved.
    27  	ErrNotFound = errors.New("not found")
    28  )
    29  
    30  type Storage interface {
    31  	// Put stores a value by key. 0-length keys results in noop.
    32  	Put(key, value string)
    33  
    34  	// Get returns the previously stored value, or an error if the key is 0-length
    35  	// or unknown.
    36  	Get(key string) (string, error)
    37  
    38  	// Del removes a key-value pair. If the key doesn't exist, the method is a noop.
    39  	Del(key string)
    40  }
    41  
    42  // EphemeralStorage is an in-memory storage that does
    43  // not persist values to disk. Mainly used for testing
    44  type EphemeralStorage struct {
    45  	data      map[string]string
    46  	namespace string
    47  }
    48  
    49  // Put stores a value by key. 0-length keys results in noop.
    50  func (s *EphemeralStorage) Put(key, value string) {
    51  	if len(key) == 0 {
    52  		return
    53  	}
    54  	s.data[key] = value
    55  }
    56  
    57  // Get returns the previously stored value, or an error if the key is 0-length
    58  // or unknown.
    59  func (s *EphemeralStorage) Get(key string) (string, error) {
    60  	if len(key) == 0 {
    61  		return "", ErrZeroKey
    62  	}
    63  	if v, ok := s.data[key]; ok {
    64  		return v, nil
    65  	}
    66  	return "", ErrNotFound
    67  }
    68  
    69  // Del removes a key-value pair. If the key doesn't exist, the method is a noop.
    70  func (s *EphemeralStorage) Del(key string) {
    71  	delete(s.data, key)
    72  }
    73  
    74  func NewEphemeralStorage() Storage {
    75  	s := &EphemeralStorage{
    76  		data: make(map[string]string),
    77  	}
    78  	return s
    79  }
    80  
    81  // NoStorage is a dummy construct which doesn't remember anything you tell it
    82  type NoStorage struct{}
    83  
    84  func (s *NoStorage) Put(key, value string) {}
    85  func (s *NoStorage) Del(key string)        {}
    86  func (s *NoStorage) Get(key string) (string, error) {
    87  	return "", errors.New("I forgot")
    88  }