wal

Package wal provides a simple write-ahead log implementation inspired by Indeed's BasicRecordFile implementation. Each record in the file is stored using the following format:

[length - varint][record content][checksum]

Unlike the reference implementation, the record length is written as a varint to help conserve space. The checksum is a simple CRC32 checksum. Reference: https://github.com/indeedeng/lsmtree/blob/master/recordlog/src/main/java/com/indeed/lsmtree/recordlog/BasicRecordFile.java

import go.pitz.tech/lib/wal

Usage

type Reader

type Reader struct {
}

Reader implements the logic for reading information from the write-ahead log. The underlying file is wrapped with a buffered reader to help improve performance.

func OpenReader

func OpenReader(ctx context.Context, filepath string) (*Reader, error)

OpenReader opens a new read-only handle to the target file.

func (*Reader) Close

func (r *Reader) Close() error

func (*Reader) Position

func (r *Reader) Position() uint64

Position returns the current position of the reader.

func (*Reader) Read

func (r *Reader) Read(p []byte) (n int, err error)

func (*Reader) Seek

func (r *Reader) Seek(offset int64, whence int) (int64, error)

type Writer

type Writer struct {
}

Writer implements the logic for writing information to the write-ahead log. The underlying file is wrapped with a buffered writer to help improve durability of writes.

func OpenWriter

func OpenWriter(ctx context.Context, filepath string) (*Writer, error)

OpenWriter opens a new append-only handle that writes data to the target file.

func (*Writer) Close

func (w *Writer) Close() error

func (*Writer) Flush

func (w *Writer) Flush() error

func (*Writer) Sync

func (w *Writer) Sync() error

func (*Writer) Write

func (w *Writer) Write(p []byte) (int, error)