wal

Documentation

Overview

Package wal implements write-ahead-log.

Index

• Constants
• func NewWALStores(vertexInstance *dfv1.VertexInstance, opts ...Option) store.StoreProvider
• type Option
  • func WithMaxBufferSize(size int64) Option
  • func WithStorePath(path string) Option
  • func WithSyncDuration(maxDuration time.Duration) Option
• type WAL
  • func (w *WAL) Close() (err error)
  • func (w *WAL) IsCorrupted() bool
  • func (w *WAL) Read(size int64) ([]*isb.ReadMessage, bool, error)
  • func (w *WAL) Write(message *isb.ReadMessage) (err error)

Constants

const (
	IEEE            = 0xedb88320
	EntryHeaderSize = 28
	SegmentPrefix   = "segment"
)

Functions

func NewWALStores

func NewWALStores(vertexInstance *dfv1.VertexInstance, opts ...Option) store.StoreProvider

Types

type Option

type Option func(stores *walStores)

func WithMaxBufferSize

func WithMaxBufferSize(size int64) Option

WithMaxBufferSize sets the WAL buffer max size option

func WithStorePath

func WithStorePath(path string) Option

WithStorePath sets the WAL store path

func WithSyncDuration

func WithSyncDuration(maxDuration time.Duration) Option

WithSyncDuration sets the WAL sync duration option

type WAL

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

WAL implements a write-ahead-log. It represents both reader and writer. This WAL is write heavy and read is infrequent, meaning a read will only happen during a boot up. WAL will only have one segment since these are relatively short-lived.

func (*WAL) Close

func (w *WAL) Close() (err error)

Close closes the WAL Segment.

func (*WAL) IsCorrupted

func (w *WAL) IsCorrupted() bool

IsCorrupted checks whether the file is corrupt

func (*WAL) Read

func (w *WAL) Read(size int64) ([]*isb.ReadMessage, bool, error)

func (*WAL) Write

func (w *WAL) Write(message *isb.ReadMessage) (err error)

Write writes the message to the WAL. The format as follow is

+-------------------+----------------+-----------------+--------------+----------------+
| watermark (int64) | offset (int64) | msg-len (int64) | CRC (unit32) | message []byte |
+-------------------+----------------+-----------------+--------------+----------------+

CRC will be used for detecting ReadMessage corruptions.