a Redisson like distributed locking implementation using Redis.
Explanation
go get github.com/cheerego/go-redisson
-
Mutex Example
- Exclusive Lock (X Lock).
- use it like std package sync.Mutex.
- not a reentrant lock that can't lock twice in a same goroutine.
-
RLock Example
- Exclusive Reentrant Lock.
- use it like java redisson.
- a reentrant lock that can lock many times in a same goroutine.
- tryLock，if waitTime > 0, wait
waitTimemilliseconds 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.
g := godisson.NewGodisson(rdb, godisson.WithWatchDogTimeout(30*time.Second))
package main import ( "github.com/cheerego/go-redisson" "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() }() time.Sleep(20 * time.Second) }
package main import ( "github.com/cheerego/go-redisson" "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() }