文章目錄

• 需求
• Leader Election
• Case
• Code
• 源碼分析

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需求

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Leader Election

https://curator.apache.org/getting-started.html

Demo示例

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Case

官方demo

https://github.com/apache/curator/tree/master/curator-examples/src/main/java/leader

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Code

我們自己也寫個(gè)demo 吧

<dependency><groupId>org.apache.curator</groupId><artifactId>curator-recipes</artifactId><version>5.0.0</version><exclusions><exclusion><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.5.8</version></dependency> import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.recipes.leader.LeaderSelector; import org.apache.curator.framework.recipes.leader.LeaderSelectorListener; import org.apache.curator.framework.recipes.leader.LeaderSelectorListenerAdapter; import org.apache.curator.retry.ExponentialBackoffRetry;import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit;public class LeaderSelectorTest {private static final String CONNECT_STR="192.168.126.135:2181";private static RetryPolicy retryPolicy=new ExponentialBackoffRetry( 5*1000, 10 );private static CuratorFramework curatorFramework;private static CountDownLatch countDownLatch = new CountDownLatch(1);public static void main(String[] args) throws InterruptedException {String appName = System.getProperty("appName");CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient(CONNECT_STR, retryPolicy);LeaderSelectorTest.curatorFramework = curatorFramework;curatorFramework.start();LeaderSelectorListener listener = new LeaderSelectorListenerAdapter(){// 選舉 leader后的回調(diào)@Overridepublic void takeLeadership(CuratorFramework client) throws Exception{// this callback will get called when you are the leader// do whatever leader work you need to and only exit// this method when you want to relinquish leadershipSystem.out.println(" LEADER . 【"+appName +"】, Pre Warm Cache ");// 模擬業(yè)務(wù)耗時(shí)操作TimeUnit.SECONDS.sleep(5);}};LeaderSelector selector = new LeaderSelector(curatorFramework, "/cache_warmer_leader", listener);selector.autoRequeue(); // not required, but this is behavior that you will probably expectselector.start();countDownLatch.await();} }

zk中的數(shù)據(jù)

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源碼分析

我們來(lái)看下 curator是怎么實(shí)現(xiàn)的？

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