如何在 Spring Integration using ZooKeeper 中围绕轮询器实现分布式锁

Question

Spring 集成具有 ZooKeeper 支持，如 https://docs.spring.io/spring-integration/reference/html/zookeeper.html 中所述但是这个文件太含糊了。

它建议在下面添加 bean，但没有详细说明如何在节点被授予领导权时 start/stop 轮询器。

@Bean
public LeaderInitiatorFactoryBean leaderInitiator(CuratorFramework client) {
    return new LeaderInitiatorFactoryBean()
                .setClient(client)
                .setPath("/siTest/")
                .setRole("cluster");
}

我们是否有任何示例说明如何使用 zookeeper 确保下面的轮询器运行在任何时候在集群中仅一次？

@Component
public class EventsPoller {

    public void pullEvents() {
        //pull events should be run by only one node in the cluster at any time
    }
}

Answer 1

LeaderInitiator 发出一个 OnGrantedEvent 和 OnRevokedEvent，当它成为领导者并且它的领导权被撤销时。

有关这些事件处理及其如何影响特定角色中的组件的更多信息，请参阅 https://docs.spring.io/spring-integration/reference/html/messaging-endpoints-chapter.html#endpoint-roles and the next https://docs.spring.io/spring-integration/reference/html/messaging-endpoints-chapter.html#leadership-event-handling。

虽然我同意 Zookkeper 章节必须有一些 link 到那个 SmartLifecycleRoleController 章节。欢迎就此事提出 JIRA，欢迎投稿！

更新

这是我在测试中所做的：

@RunWith(SpringRunner.class)
@DirtiesContext
public class LeaderInitiatorFactoryBeanTests extends ZookeeperTestSupport {

    private static CuratorFramework client;

    @Autowired
    private PollableChannel stringsChannel;

    @BeforeClass
    public static void getClient() throws Exception {
        client = createNewClient();
    }

    @AfterClass
    public static void closeClient() {
        if (client != null) {
            client.close();
        }
    }

    @Test
    public void test() {
        assertNotNull(this.stringsChannel.receive(10_000));
    }


    @Configuration
    @EnableIntegration
    public static class Config {

        @Bean
        public LeaderInitiatorFactoryBean leaderInitiator(CuratorFramework client) {
            return new LeaderInitiatorFactoryBean()
                    .setClient(client)
                    .setPath("/siTest/")
                    .setRole("foo");
        }

        @Bean
        public CuratorFramework client() {
            return LeaderInitiatorFactoryBeanTests.client;
        }

        @Bean
        @InboundChannelAdapter(channel = "stringsChannel", autoStartup = "false", poller = @Poller(fixedDelay = "100"))
        @Role("foo")
        public Supplier<String> inboundChannelAdapter() {
            return () -> "foo";
        }

        @Bean
        public PollableChannel stringsChannel() {
            return new QueueChannel();
        }

    }

}

我在日志中有这样的内容：

2018-12-14 10:12:33,542 DEBUG [Curator-LeaderSelector-0] [org.springframework.integration.support.SmartLifecycleRoleController] - Starting [leaderInitiatorFactoryBeanTests.Config.inboundChannelAdapter.inboundChannelAdapter] in role foo
2018-12-14 10:12:33,578 DEBUG [Curator-LeaderSelector-0] [org.springframework.integration.support.SmartLifecycleRoleController] - Stopping [leaderInitiatorFactoryBeanTests.Config.inboundChannelAdapter.inboundChannelAdapter] in role foo

如何在 Spring Integration using ZooKeeper 中围绕轮询器实现分布式锁

How to implement distributed lock around poller in Spring Integration using ZooKeeper

spring-integration

apache-zookeeper

spring-integration-dsl

spring-cloud-zookeeper