wal

README

wal

simple/small write ahead log.

Installation

$ go get github.com/octu0/wal

Example

import "github.com/octu0/wal"

func main() {
	log, err := Open("/path/to/dir", wal.WithSync(true))
	if err != nil {
		panic(err)
	}
	defer log.Close()

	i1, err := log.Write([]byte("data1"))
	i2, err := log.Write([]byte("data2"))
	err := log.WriteAt(Index(100), []byte("data3"))

	data1, _ := log.Read(i1)
	println(string(data1)) // => "data1"

	data3, _ := log.Read(Index(100))
	println(string(data3)) // => "data3"

	// delete logs on memory
	if err := log.Delete(i1, i2); err != nil {
		panic(err)
	}

	// compaction of deleted logs to free disk space
	if err := log.Compact(); err != nil {
		panic(err)
	}
}

License

MIT, see LICENSE file for details.

Documentation

Overview

Example

dir, err := os.MkdirTemp("", "testdir")
if err != nil {
	panic(err)
}

log, err := Open(dir)
if err != nil {
	panic(err)
}

i1, _ := log.Write([]byte("data1"))
i2, _ := log.Write([]byte("data2"))
_ = log.WriteAt(Index(100), []byte("data3"))

data1, _ := log.Read(i1)
fmt.Println(string(data1))

data3, _ := log.Read(Index(100))
fmt.Println(string(data3))

// delete logs on memory
if err := log.Delete(i1, i2); err != nil {
	panic(err)
}

// compaction of deleted logs to free disk space
if err := log.Compact(); err != nil {
	panic(err)
}

Output:

data1
data3

Index

• Constants
• Variables
• type DataLoadFunc
• type FileID
  • func CreateFileID(t, r int64) FileID
  • func NextFileID() FileID
  • func ParseFileID(fileID string) (FileID, bool)
  • func (f FileID) Equal(target FileID) bool
  • func (f FileID) IsZero() bool
  • func (f FileID) Newer(target FileID) bool
  • func (f FileID) String() string
• type FileLocker
  • func NewFileLocker(path string) *FileLocker
  • func (lock *FileLocker) TryLock() error
  • func (lock *FileLocker) Unlock() error
• type Index
• type Locker
• type Log
  • func Open(dir string, funcs ...OptionFunc) (*Log, error)
  • func (l *Log) Close() error
  • func (l *Log) Compact() error
  • func (l *Log) Delete(idxs ...Index) error
  • func (l *Log) LastIndex() Index
  • func (l *Log) Len() int
  • func (l *Log) NeedCompaction() bool
  • func (l *Log) Read(idx Index) ([]byte, error)
  • func (l *Log) ReadFrom(r io.Reader) (int64, error)
  • func (l *Log) ReclaimableSpace() uint64
  • func (l *Log) Segments() int
  • func (l *Log) Size() uint64
  • func (l *Log) Sync() error
  • func (l *Log) Write(data []byte) (Index, error)
  • func (l *Log) WriteAt(idx Index, data []byte) error
  • func (l *Log) WriteTo(w io.Writer) (int64, error)
• type OptionFunc
  • func WithCloseCompaction(enable bool) OptionFunc
  • func WithDataLoadFunc(fn DataLoadFunc) OptionFunc
  • func WithMaxSegmentSize(size uint64) OptionFunc
  • func WithSync(enable bool) OptionFunc
  • func WithWriteBufferSize(size int) OptionFunc

Examples

• Package

Constants

const (
	AppName string = "wal"
	Version string = "1.1.0"
)

const (
	FileIDByteSize int = 8 + 8
)

Variables

var (
	ErrClosed         = errors.New("closed")
	ErrCompactRunning = errors.New("compat already in progress")
	ErrNotFound       = errors.New("not found")
	ErrSegmentNotOpen = errors.New("segment not open")
)

var (
	ErrLocked = errors.Errorf("locked")
)

Types

type DataLoadFunc

type DataLoadFunc func(Index, []byte) error

type FileID

type FileID struct {
	Time int64
	Rand int64
}

func CreateFileID

func CreateFileID(t, r int64) FileID

func NextFileID

func NextFileID() FileID

func ParseFileID

func ParseFileID(fileID string) (FileID, bool)

func (FileID) Equal

func (f FileID) Equal(target FileID) bool

func (FileID) IsZero

func (f FileID) IsZero() bool

func (FileID) Newer

func (f FileID) Newer(target FileID) bool

func (FileID) String

func (f FileID) String() string

type FileLocker

type FileLocker struct {
	// contains filtered or unexported fields
}

func NewFileLocker

func NewFileLocker(path string) *FileLocker

func (*FileLocker) TryLock

func (lock *FileLocker) TryLock() error

func (*FileLocker) Unlock

func (lock *FileLocker) Unlock() error

type Index

type Index codec.ID

type Locker

type Locker interface {
	TryLock() error
	Unlock() error
}

type Log

type Log struct {
	// contains filtered or unexported fields
}

func Open

func Open(dir string, funcs ...OptionFunc) (*Log, error)

func (*Log) Close

func (l *Log) Close() error

func (*Log) Compact

func (l *Log) Compact() error

func (*Log) Delete

func (l *Log) Delete(idxs ...Index) error

func (*Log) LastIndex

func (l *Log) LastIndex() Index

func (*Log) Len

func (l *Log) Len() int

func (*Log) NeedCompaction

func (l *Log) NeedCompaction() bool

func (*Log) Read

func (l *Log) Read(idx Index) ([]byte, error)

func (*Log) ReadFrom

func (l *Log) ReadFrom(r io.Reader) (int64, error)

func (*Log) ReclaimableSpace

func (l *Log) ReclaimableSpace() uint64

func (*Log) Segments

func (l *Log) Segments() int

func (*Log) Size

func (l *Log) Size() uint64

func (*Log) Sync

func (l *Log) Sync() error

func (*Log) Write

func (l *Log) Write(data []byte) (Index, error)

func (*Log) WriteAt

func (l *Log) WriteAt(idx Index, data []byte) error

func (*Log) WriteTo

func (l *Log) WriteTo(w io.Writer) (int64, error)

type OptionFunc

type OptionFunc func(*logOpt)

func WithCloseCompaction

func WithCloseCompaction(enable bool) OptionFunc

func WithDataLoadFunc

func WithDataLoadFunc(fn DataLoadFunc) OptionFunc

func WithMaxSegmentSize

func WithMaxSegmentSize(size uint64) OptionFunc

func WithSync

func WithSync(enable bool) OptionFunc

func WithWriteBufferSize

func WithWriteBufferSize(size int) OptionFunc