Mastering tldb Distributed Locks: Go, Java, and Python Examples

What is a Distributed Lock?

Distributed locks are essential tools in distributed systems. tldb provides a simple, reliable distributed lock that works like an object lock in a program, using third‑party services such as Redis, MQ, databases, or Zookeeper.

tldb Distributed Lock API

Lock(string, int)

– blocking request for a lock. TryLock(string, int) – non‑blocking attempt; returns a key if successful. Unlock(string) – releases the lock.

The lock is controlled by the tldb server, making it language‑agnostic. Clients in Java, Go, Python, and JavaScript are already available, and other languages can be added easily.

Lock Method Usage

The Lock method takes two parameters: the lock name (e.g., "abc") and the maximum hold time in seconds. If the lock is not released within the timeout, the server forces its release.

Unlock Method Usage

After acquiring a lock, the server returns a key. The client must call Unlock(key) to release the lock; otherwise the server will release it after the timeout.

TryLock Method Usage

TryLock

behaves like Lock but returns immediately. If the lock is available, it returns a key and a success flag; otherwise it returns empty data.

Go Example

import "github.com/donnie4w/tlmq-go/cli"

sc := cli.NewMqClient("ws://127.0.0.1:5001", "mymq=123")
sc.Connect()
key, err := sc.Lock("testlock", 3)
if err != nil {
    // handle error
} else {
    defer sc.UnLock(key)
    // business logic
}

TryLock example with spin‑wait:

sc := cli.NewMqClient("ws://127.0.0.1:5001", "mymq=123")
sc.Connect()
var key string
for {
    if v, ok := sc.TryLock("testlock", 3); ok {
        key = v
        break
    }
    <-time.After(100 * time.Millisecond)
}
defer sc.UnLock(key)
// business logic

Java Example

MqClient mc = new SimpleClient("ws://127.0.0.1:5001", "mymq=123");
mc.connect();
String key = null;
try {
    key = mc.lock("testlock", 3);
    // business logic
} finally {
    if (key != null) {
        mc.unLock(key);
    }
}

Test Results

Multi‑threaded concurrency tests show lock acquisition behavior for both Lock and TryLock (spin).