Implementation:Apache Shardingsphere EtcdDistributedLock Lock

Knowledge Sources	Apache_Shardingsphere
Domains	Distributed_Locking, Etcd
Last Updated	2026-02-10 00:00 GMT

Overview

EtcdDistributedLock implements distributed locking using the etcd Lock and Lease APIs with configurable time-to-live for lock leases.

Description

EtcdDistributedLock implements the DistributedLock interface using the etcd Java client (jetcd). The constructor converts the lock key to a ByteSequence, obtains Lock and Lease clients from the etcd Client, and reads the time-to-live seconds from EtcdProperties. The tryLock method first grants a lease with the configured TTL, then calls lock.lock with the lease ID, waiting up to the specified timeout. If acquisition succeeds, it returns true. InterruptedException restores the interrupt flag and returns false; ExecutionException and TimeoutException also return false. The unlock method calls lock.unlock asynchronously and waits for completion, handling exceptions gracefully.

Usage

This lock implementation is automatically used when etcd is the configured cluster persist repository. It provides distributed mutual exclusion backed by etcd's native lease-based locking, with automatic lock expiration via the TTL.

Code Reference

Source Location

• Repository: Apache_Shardingsphere
• File: EtcdDistributedLock.java
• Lines: 1-75

Signature

public final class EtcdDistributedLock implements DistributedLock {

    public EtcdDistributedLock(final String lockKey, final Client client, final EtcdProperties props)

    public boolean tryLock(final long timeoutMillis)

    public void unlock()
}

Import

import org.apache.shardingsphere.mode.repository.cluster.etcd.lock.EtcdDistributedLock;

I/O Contract

Inputs

Name	Type	Required	Description
lockKey	String	Yes	Key path for the distributed lock
client	Client	Yes	etcd client providing Lock and Lease clients
props	EtcdProperties	Yes	Properties containing TIME_TO_LIVE_SECONDS
timeoutMillis	long	Yes	Maximum time to wait for lock acquisition

Outputs

Name	Type	Description
isLocked	boolean	Whether the lock was acquired within the timeout

Usage Examples

EtcdDistributedLock lock = new EtcdDistributedLock("/locks/config_change", etcdClient, etcdProps);
if (lock.tryLock(5000L)) {
    try {
        // Lock acquired with a lease TTL; auto-expires if holder crashes
        performExclusiveOperation();
    } finally {
        lock.unlock();
    }
}

Related Pages

• Principle:Apache_Shardingsphere_Exclusive_Operation_Management