Distributed lock implementation in Golang using consul
d, err = dlock.New(&dlock.Config{ConsulKey: "LockKV", LockRetryInterval: time.Second * 10})
if err != nil {
log.Println("Error ", err)
return
}acquireCh := make(chan bool)
releaseCh := make(chan bool)
for { // loop is to re-attempt for lock acquisition when the lock was initially acquired but auto released after some time
log.Println("try to acquire lock")
value := map[string]string{
"key1": "val1",
// Optional keys
// Any number of similar keys can be added with the limit of 512KB. as mentioned here - https://www.consul.io/docs/faq.html#q-what-is-the-per-key-value-size-limitation-for-consul-39-s-key-value-store-
// key named `lockAcquisitionTime` is automatically added. This is the time at which lock is acquired. time is in RFC3339 format
}
go d.RetryLockAcquire(value, acquireCh, releaseCh) // It will keep on attempting for the lock. The re-attempt interval is configured through `LockRetryInterval`, which is set while dlock initialization.
select {
case <-acquireCh:
log.Println("log acquired")
}
<-releaseCh // lock is released due to session invalidation
log.Println("log released")
}acquireCh recieves msg when the lock is acquired, otherwise blocks and wait for lock acquisition and compete with others for the lock
releaseCh recieves msg when the lock which was earlier acquired is released due to some reason(consul session invalidation etc)
if err := d.DestroySession(); err != nil { // Should be called during clean-up. eg reloading the service. Can be done by catching SIGHUP signal
//Destroy session will release the lock and give others a chance to acquire the lock
log.Println(err)
}