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backend.go
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backend.go
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/*
* Copyright 2020, Cossack Labs Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Package api defines abstract backend interface.
package api
import (
"errors"
)
// PathSeparator used in key paths.
const PathSeparator = "/"
// Errors returned by filesystem.Backend:
var (
ErrNotExist = errors.New("key path does not exist")
ErrExist = errors.New("key path already exists")
ErrInvalidPath = errors.New("invalid key path")
)
// Backend defines how KeyStore persists internal key data.
type Backend interface {
// Get data at given path.
// Returns ErrNotExist if path does not exist.
Get(path string) ([]byte, error)
// Put data at given path.
// Returns ErrExist if path already exists.
Put(path string, data []byte) error
// ListAll enumerates all paths currently stored.
// The paths are returned in lexicographical order.
ListAll() ([]string, error)
// Rename oldpath into newpath atomically.
// Replaces newpath if it already exists.
// Returns ErrNotExist if oldpath does not exist.
Rename(oldpath, newpath string) error
// Rename oldpath into newpath non-destructively.
// Returns ErrExist if newpath already exists.
// Returns ErrNotExist if oldpath does not exist.
RenameNX(oldpath, newpath string) error
// Lock acquires an exclusive lock on the store, suitable for writing.
// This call blocks until the lock is acquired.
// It can also deadlock if you already hold the lock.
Lock() error
// RLock acquires a shared lock on the store, suitable for reading.
// This call blocks until the lock is acquired.
RLock() error
// Unlock releases the exclusive lock currently held by the process.
// It is an error to call it without calling Lock() first.
Unlock() error
// RUnlock releases the shared lock currently held by the process.
// It is an error to call it without calling RLock() first.
RUnlock() error
// Close this backend instance, freeing any associated resources.
// This implicitly unlocks the store if any locks are held.
Close() error
}