go-redisson

a Redisson like distributed locking implementation using Redis.

Installation

go get github.com/cheerego/go-redisson

Lock Category

  • Mutex
  1. Exclusive Lock (X Lock).
  2. use it like std package sync.Mutex.
  3. not a reentrant lock that can’t lock twice in a same goroutine.
  • RLock
  1. Exclusive Reentrant Lock.
  2. use it like java redisson.
  3. a reentrant lock that can lock many times in a same goroutine.

Features

  • tryLock，if waitTime > 0, wait waitTime milliseconds to try to obtain lock by while true and redis pub sub.
  • watchdog, if leaseTime = -1, start a time.Ticker(defaultWatchDogTime / 3) to renew lock expiration time.

Options

WatchDogTimeout

g := godisson.NewGodisson(rdb, godisson.WithWatchDogTimeout(30*time.Second))

Examples

Mutex

package examples

import (
	"github.com/cheerego/godisson"
	"github.com/go-redis/redis/v8"
	"github.com/pkg/errors"
	"log"
	"time"
)

func main() {

	// create redis client
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "", // no password set
		DB:       0,  // use default DB
	})
	defer rdb.Close()

	g := godisson.NewGodisson(rdb, godisson.WithWatchDogTimeout(30*time.Second))

	test1(g)
	test2(g)
}

// can't obtain lock in a same goroutine
func test1(g *godisson.Godisson) {
	m1 := g.NewMutex("godisson")
	m2 := g.NewMutex("godisson")

	err := m1.TryLock(-1, 20000)
	if errors.Is(err, godisson.ErrLockNotObtained) {
		log.Println("can't obtained lock")
	} else if err != nil {
		log.Fatalln(err)
	}
	defer m1.Unlock()

	// because waitTime = -1, waitTime < 0, try once, will return ErrLockNotObtained
	err = m2.TryLock(-1, 20000)
	if errors.Is(err, godisson.ErrLockNotObtained) {
		log.Println("m2 must not obtained lock")
	} else if err != nil {
		log.Fatalln(err)
	}
	time.Sleep(10 * time.Second)
}

func test2(g *godisson.Godisson) {
	m1 := g.NewMutex("godisson")
	m2 := g.NewMutex("godisson")

	go func() {
		err := m1.TryLock(-1, 20000)
		if errors.Is(err, godisson.ErrLockNotObtained) {
			log.Println("can't obtained lock")
		} else if err != nil {
			log.Fatalln(err)
		}
		time.Sleep(10 * time.Second)
		m1.Unlock()
	}()

	// waitTime > 0, after 10 milliseconds will obtain the lock
	go func() {
		time.Sleep(1 * time.Second)
		
		err := m2.TryLock(15000, 20000)
		if errors.Is(err, godisson.ErrLockNotObtained) {
			log.Println("m2 must not obtained lock")
		} else if err != nil {
			log.Fatalln(err)
		}
		time.Sleep(10 * time.Second)

		m2.Unlock()
	}()

}

RLock

package examples

import (
	"github.com/cheerego/godisson"
	"github.com/go-redis/redis/v8"
	"log"
	"time"
)

func main() {

	// create redis client
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "", // no password set
		DB:       0,  // use default DB
	})
	defer rdb.Close()

	g := godisson.NewGodisson(rdb, godisson.WithWatchDogTimeout(30*time.Second))

	// lock with watchdog without retry
	lock := g.NewRLock("godisson")

	err := lock.Lock()
	if err == godisson.ErrLockNotObtained {
		log.Println("Could not obtain lock")
	} else if err != nil {
		log.Fatalln(err)
	}
	defer lock.Unlock()

	// lock with retry、watchdog
	// leaseTime value is -1, enable watchdog
	lock2 := g.NewRLock("godission-try-watchdog")

	err = lock2.TryLock(20000, -1)
	if err == godisson.ErrLockNotObtained {
		log.Println("Could not obtain lock")
	} else if err != nil {
		log.Fatalln(err)
	}
	time.Sleep(10 * time.Second)
	defer lock.Unlock()
}

GitHub

View Github