+++ /dev/null
-// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
-// All rights reserved.
-//
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Package storage provides storage abstraction for LevelDB.
-package storage
-
-import (
- "errors"
- "fmt"
- "io"
-)
-
-// FileType represent a file type.
-type FileType int
-
-// File types.
-const (
- TypeManifest FileType = 1 << iota
- TypeJournal
- TypeTable
- TypeTemp
-
- TypeAll = TypeManifest | TypeJournal | TypeTable | TypeTemp
-)
-
-func (t FileType) String() string {
- switch t {
- case TypeManifest:
- return "manifest"
- case TypeJournal:
- return "journal"
- case TypeTable:
- return "table"
- case TypeTemp:
- return "temp"
- }
- return fmt.Sprintf("<unknown:%d>", t)
-}
-
-// Common error.
-var (
- ErrInvalidFile = errors.New("leveldb/storage: invalid file for argument")
- ErrLocked = errors.New("leveldb/storage: already locked")
- ErrClosed = errors.New("leveldb/storage: closed")
-)
-
-// ErrCorrupted is the type that wraps errors that indicate corruption of
-// a file. Package storage has its own type instead of using
-// errors.ErrCorrupted to prevent circular import.
-type ErrCorrupted struct {
- Fd FileDesc
- Err error
-}
-
-func (e *ErrCorrupted) Error() string {
- if !e.Fd.Zero() {
- return fmt.Sprintf("%v [file=%v]", e.Err, e.Fd)
- }
- return e.Err.Error()
-}
-
-// Syncer is the interface that wraps basic Sync method.
-type Syncer interface {
- // Sync commits the current contents of the file to stable storage.
- Sync() error
-}
-
-// Reader is the interface that groups the basic Read, Seek, ReadAt and Close
-// methods.
-type Reader interface {
- io.ReadSeeker
- io.ReaderAt
- io.Closer
-}
-
-// Writer is the interface that groups the basic Write, Sync and Close
-// methods.
-type Writer interface {
- io.WriteCloser
- Syncer
-}
-
-// Locker is the interface that wraps Unlock method.
-type Locker interface {
- Unlock()
-}
-
-// FileDesc is a 'file descriptor'.
-type FileDesc struct {
- Type FileType
- Num int64
-}
-
-func (fd FileDesc) String() string {
- switch fd.Type {
- case TypeManifest:
- return fmt.Sprintf("MANIFEST-%06d", fd.Num)
- case TypeJournal:
- return fmt.Sprintf("%06d.log", fd.Num)
- case TypeTable:
- return fmt.Sprintf("%06d.ldb", fd.Num)
- case TypeTemp:
- return fmt.Sprintf("%06d.tmp", fd.Num)
- default:
- return fmt.Sprintf("%#x-%d", fd.Type, fd.Num)
- }
-}
-
-// Zero returns true if fd == (FileDesc{}).
-func (fd FileDesc) Zero() bool {
- return fd == (FileDesc{})
-}
-
-// FileDescOk returns true if fd is a valid 'file descriptor'.
-func FileDescOk(fd FileDesc) bool {
- switch fd.Type {
- case TypeManifest:
- case TypeJournal:
- case TypeTable:
- case TypeTemp:
- default:
- return false
- }
- return fd.Num >= 0
-}
-
-// Storage is the storage. A storage instance must be safe for concurrent use.
-type Storage interface {
- // Lock locks the storage. Any subsequent attempt to call Lock will fail
- // until the last lock released.
- // Caller should call Unlock method after use.
- Lock() (Locker, error)
-
- // Log logs a string. This is used for logging.
- // An implementation may write to a file, stdout or simply do nothing.
- Log(str string)
-
- // SetMeta store 'file descriptor' that can later be acquired using GetMeta
- // method. The 'file descriptor' should point to a valid file.
- // SetMeta should be implemented in such way that changes should happen
- // atomically.
- SetMeta(fd FileDesc) error
-
- // GetMeta returns 'file descriptor' stored in meta. The 'file descriptor'
- // can be updated using SetMeta method.
- // Returns os.ErrNotExist if meta doesn't store any 'file descriptor', or
- // 'file descriptor' point to nonexistent file.
- GetMeta() (FileDesc, error)
-
- // List returns file descriptors that match the given file types.
- // The file types may be OR'ed together.
- List(ft FileType) ([]FileDesc, error)
-
- // Open opens file with the given 'file descriptor' read-only.
- // Returns os.ErrNotExist error if the file does not exist.
- // Returns ErrClosed if the underlying storage is closed.
- Open(fd FileDesc) (Reader, error)
-
- // Create creates file with the given 'file descriptor', truncate if already
- // exist and opens write-only.
- // Returns ErrClosed if the underlying storage is closed.
- Create(fd FileDesc) (Writer, error)
-
- // Remove removes file with the given 'file descriptor'.
- // Returns ErrClosed if the underlying storage is closed.
- Remove(fd FileDesc) error
-
- // Rename renames file from oldfd to newfd.
- // Returns ErrClosed if the underlying storage is closed.
- Rename(oldfd, newfd FileDesc) error
-
- // Close closes the storage.
- // It is valid to call Close multiple times. Other methods should not be
- // called after the storage has been closed.
- Close() error
-}
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