The method and principle of distributed locks with Curator Framework to implement distributed locks
Use Curator Framework to implement the method and principle of distributed locks
A distributed system often needs to use a distributed lock to control access to shared resources.Curator Framework is a high -end library for distributed system development, providing a method of implementing distributed locks.This article will introduce the principle of using Curator Framework to implement distributed locks and some commonly used methods in practical applications.
Curator Framework is part of the Apache Curator project and is a Java client library for Apachekeeper.ZooKeeper is a highly available, high -performance distributed coordination service, which provides the characteristics of atomic operation and order consistency, which is very suitable for achieving distributed locks.
There are two main methods for achieving distributed locks using Curator Framework: locks based on shared order nodes and InterprocessMutex locks.The principles and example code of these two methods will be introduced in turn.
1. Lock based on sharing order nodes
Locks based on shared order nodes are a classic distributed lock implementation.Its principle is to use the order of the node of Zookeeper. The client will create an orderly temporary node when trying to get the lock, and then check whether it is the smallest node.If it is the minimum node, the lock is successfully obtained, otherwise the deletion event of the previous node is listened to.Once the previous node is deleted, the current node is the minimum node and get the lock.
Below is a sample code that uses Curator Framework to implement locks based on shared nodes:
public class DistributedLock {
private CuratorFramework client;
private InterProcessMutex lock;
public DistributedLock(String connectionString, String lockPath) {
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
client = CuratorFrameworkFactory.newClient(connectionString, retryPolicy);
client.start();
lock = new InterProcessMutex(client, lockPath);
}
public void acquireLock() throws Exception {
lock.acquire();
}
public void releaseLock() throws Exception {
lock.release();
}
}
Use the example code as follows:
public class Main {
public static void main(String[] args) {
DistributedLock lock = new DistributedLock("localhost:2181", "/locks");
try {
lock.acquireLock();
// Execute code blocks that need to be protected
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
lock.releaseLock();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
In the above example code, we first create a CuratorFramework client and initialize an interprocessMutex lock object.Then, call the `Acquirelock ()` method to obtain the lock in the code block that needs to be protected.
2. Lock based on InterprocessMutex
Curator Framework also provides a more simple distributed lock implementation method, that is, the InterprocessMutex lock.InterprocessMutex is a recurred lock implementation provided by Curator Framework. Its principle is to use the temporary sequential node and node Watch mechanism of Zookeeper to achieve distributed locks.
Below is a sample code that uses Curator Framework to implement an interprochssmutex lock:
public class DistributedLock {
private CuratorFramework client;
private InterProcessMutex lock;
public DistributedLock(String connectionString, String lockPath) {
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
client = CuratorFrameworkFactory.newClient(connectionString, retryPolicy);
client.start();
lock = new InterProcessMutex(client, lockPath);
}
public void acquireLock() throws Exception {
lock.acquire();
}
public void releaseLock() throws Exception {
lock.release();
}
}
Use the example code as follows:
public class Main {
public static void main(String[] args) {
DistributedLock lock = new DistributedLock("localhost:2181", "/locks");
try (InterProcessMutex ignored = lock.acquireLock()) {
// Execute code blocks that need to be protected
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above example code, we used the Java 7 Try-With-Resources syntax from the release lock.Just declare the return value of the `lock.acquirelock () method to the interprocessMutex type, and use the` IGNORD` variable in the TRY block.
In summary, the method of implementing a distributed lock using Curator Framework mainly includes locks based on shared order nodes and interprocessMutex locks.No matter which method is selected, a distributed lock can be achieved through the rich features provided by Curator Framework and an easy -to -use API to ensure the consistency and reliability of the system.
