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.