diff options
Diffstat (limited to 'vendor/github.com/syndtr/goleveldb/leveldb/storage/storage.go')
-rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/storage/storage.go | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/storage/storage.go b/vendor/github.com/syndtr/goleveldb/leveldb/storage/storage.go new file mode 100644 index 000000000..c16bce6b6 --- /dev/null +++ b/vendor/github.com/syndtr/goleveldb/leveldb/storage/storage.go @@ -0,0 +1,179 @@ +// 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 +} |