Redsync

Redsync provides a Redis-based distributed mutual exclusion lock implementation for Go as described in this post. A reference library (by antirez) for Ruby is available at github.com/antirez/redlock-rb.

Installation

Install Redsync using the go get command:

$ go get github.com/go-redsync/redsync/v4

Two driver implementations will be installed; however, only the one used will be included in your project.

• Redigo
• Go-redis

See the examples folder for usage of each driver.

Documentation

• Reference

Usage

Error handling is simplified to panic for shorter example.

package main

import (
	goredislib "github.com/redis/go-redis/v9"
	"github.com/go-redsync/redsync/v4"
	"github.com/go-redsync/redsync/v4/redis/goredis/v9"
)

func main() {
	// Create a pool with go-redis (or redigo) which is the pool redsync will
	// use while communicating with Redis. This can also be any pool that
	// implements the `redis.Pool` interface.
	client := goredislib.NewClient(&goredislib.Options{
		Addr: "localhost:6379",
	})
	pool := goredis.NewPool(client) // or, pool := redigo.NewPool(...)

	// Create an instance of redsync to be used to obtain a mutual exclusion
	// lock.
	rs := redsync.New(pool)

	// Obtain a new mutex by using the same name for all instances wanting the
	// same lock.
	mutexname := "my-global-mutex"
	mutex := rs.NewMutex(mutexname)

	// Obtain a lock for our given mutex. After this is successful, no one else
	// can obtain the same lock (the same mutex name) until we unlock it.
	if err := mutex.Lock(); err != nil {
		panic(err)
	}

	// Do your work that requires the lock.

	// Release the lock so other processes or threads can obtain a lock.
	if ok, err := mutex.Unlock(); !ok || err != nil {
		panic("unlock failed")
	}
}

Contributing

Contributions are welcome.

License

Redsync is available under the BSD (3-Clause) License.

Disclaimer

This code implements an algorithm which is currently a proposal, it was not formally analyzed. Make sure to understand how it works before using it in production environments.

Real World Uses

Below is a list of public, open source projects that use Redsync:

• Sourcegraph: Universal code search and intelligence platform. Uses Redsync in an internal cache implementation.
• Open Match by Google: Flexible, extensible, and scalable video game matchmaking. Uses Redsync with its state store implementation.
• Gocron by go-co-op: gocron is a job distributed scheduling package which lets you run Go functions at pre-determined intervals using a simple, human-friendly syntax. Uses Redsync with its distributed job scheduler implementation.

If you are using Redsync in a project please send a pull request to add it to the list.