govclock

Introduction

The govclock project offers full vector clock support for the Go language. Vector clocks allow recording and analyzing the inherent partial ordering of events in a distributed system in a comfortable way. The following pair of blog posts from Basho describes them in a nicely understandable way:

The following features are offered by govclock, in addition to basic event tracking:

Compact serialization and deserialization
Flexible truncation (min/max entries, min/max update time)
Unit-independent update times
Traditional merging
Fast and memory efficient

API documentation

The API documentation is currently available at:

http://goneat.org/pkg/launchpad.net/govclock

Example

Here is a simple example simulating a few sequential and concurrent operations and comparing the resulting vector clocks.


package main

import (
    "launchpad.net/govclock"
    "fmt"
)

func main() {
    vc1 := govclock.New()
    vc1.Update([]byte("A"), 1)

    vc2 := vc1.Copy()
    vc2.Update([]byte("B"), 0)

    fmt.Println(vc2.Compare(vc1, govclock.Ancestor))   // => true
    fmt.Println(vc1.Compare(vc2, govclock.Descendant)) // => true

    vc1.Update([]byte("C"), 5)


    fmt.Println(vc1.Compare(vc2, govclock.Descendant)) // => false
    fmt.Println(vc1.Compare(vc2, govclock.Concurrent)) // => true

    vc2.Merge(vc1)

    fmt.Println(vc1.Compare(vc2, govclock.Descendant)) // => true

    data := vc2.Bytes()
    fmt.Printf("%#v\n", string(data))
    // => "\x01\x01\x01\x01A\x01\x01\x01B\x01\x00\x01C"

    vc3, err := govclock.FromBytes(data)
    if err != nil { panic(err.String()) }

    fmt.Println(vc3.Compare(vc2, govclock.Equal))      // => true
}

Source code

To obtain the source code, use Bazaar to download it from Launchpad:


$ bzr branch lp:govclock

Reporting bugs

Please report bugs at:

https://launchpad.net/govclock

How to build and install govclock

Just use goinstall: $ goinstall launchpad.net/govclock

License

govclock is made available under the simplified BSD license.

Contact

Gustavo Niemeyer <gustavo@niemeyer.net>