「周末福报」初识 curator

FoamValue

修改于 2020-08-31 17:29:42

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修改于 2020-08-31 17:29:42

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Apache Curator is a Java/JVM client library for Apache ZooKeeper, a distributed coordination service. http://curator.apache.org

Apache Curator是用于Apache ZooKeeper（一种分布式协调服务）的Java / JVM客户端库。

在这之前，作为一条舒适区咸鱼的我来说，真的是完全没有听说过 Curator 这个东西😭。

同样是 Apache 大家庭的成员 —— Zookeeper 却经常能在各大技术论坛中找到它的身影。

用一句话来介绍 Zookeeper：它是一个开源的高度可靠的分布式协调的开源服务器。

Curator 基础

Maven 依赖

curator-recipes
- All of the recipes. Note: this artifact has dependencies on client and framework and, so, Maven (or whatever tool you're using) should pull those in automatically.
curator-async
- Asynchronous DSL with O/R modeling, migrations and many other features.
curator-framework
- The Curator Framework high level API. This is built on top of the client and should pull it in automatically.
curator-client
- The Curator Client - replacement for the ZooKeeper class in the ZK distribution.
curator-test
- Contains the TestingServer, the TestingCluster and a few other tools useful for testing.
curator-examples
- Example usages of various Curator features.
curator-x-discovery
- A Service Discovery implementation built on the Curator Framework.
org.apache.curator
- urator-x-discovery-server A RESTful server that can be used with Curator Discovery.

Curator 实战

创建会话

 private static CuratorFramework getZkClient() {
    RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 5);
    CuratorFramework curatorFramework = CuratorFrameworkFactory.builder()
            .connectString("127.0.0.1:2181")
            .retryPolicy(retryPolicy)
            .build();
    curatorFramework.start();
    return curatorFramework;
}

创建数据节点

private static Set<String> registeredPathSet = ConcurrentHashMap.newKeySet();
public static void createPersistentNode(String path) {
  try {
    if (registeredPathSet.contains(path) || getZkClient().checkExists().forPath(path) != null) {
      System.out.println(String.format("节点已经存在，节点为:[{}]", path));
    } else {
      getZkClient().create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path);
      System.out.println(String.format("节点创建成功，节点为:[{}]", path));
    }
    registeredPathSet.add(path);
  } catch (Exception e) {
    e.printStackTrace();
  }
}

删除数据节点

public static void removeChildrenNodes(String path) {
  try {
    getZkClient()
      .delete()
      .deletingChildrenIfNeeded()
      .forPath(path);
  } catch (Exception e) {
    e.printStackTrace();
  }
}

读取数据节点

public static List<String> getChildrenNodes(String path) {
  List<String> result = null;
  try {
    result = getZkClient().getChildren().forPath(path);
  } catch (Exception e) {
    e.printStackTrace();
  }
  return result;
}

Zookeeper 数据格式

[zk: 127.0.0.1:2181(CONNECTED) 3] get /my-rpc

cZxid = 0x25 # 节点分配的Id
ctime = Sun Jun 14 08:24:47 UTC 2020 # 节点创建时间
mZxid = 0x25 # 修改后的id
mtime = Sun Jun 14 08:24:47 UTC 2020 # 修改时间
pZxid = 0x26 # 子节点id
cversion = 1 # 子节点的version
dataVersion = 0 # 当前节点数据的版本号
aclVersion = 0 #  权限Version
ephemeralOwner = 0x0 # 临时基节点ID编号，持久节点的id为0
dataLength = 0 # 数据长度
numChildren = 1 # 子节点个数

小结

写到这里，The Last of Us: Part II 好像下载完成了