org.apache.twill.zookeeper.ZKClient.exists()方法的使用及代码示例

x33g5p2x  于2022-02-05 转载在 其他  
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本文整理了Java中org.apache.twill.zookeeper.ZKClient.exists()方法的一些代码示例，展示了ZKClient.exists()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。ZKClient.exists()方法的具体详情如下：
包路径：org.apache.twill.zookeeper.ZKClient
类名称：ZKClient
方法名：exists

ZKClient.exists介绍

[英]Checks if the path exists. Same as calling #exists(String,org.apache.zookeeper.Watcher).
[中]检查路径是否存在。与调用#exists相同（String，org.apache.zookeeper.Watcher）。

代码示例

代码示例来源：origin: org.apache.twill/twill-zookeeper

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return client.exists(path, watcher);
}

代码示例来源：origin: apache/twill

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return delegate.exists(path, watcher);
}

代码示例来源：origin: apache/twill

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return client.exists(path, watcher);
}

代码示例来源：origin: org.apache.twill/twill-zookeeper

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return delegate.exists(path, watcher);
}

代码示例来源：origin: caskdata/coopr

/**
 * Starts watching for the max. of smaller node.
 */
private void watchNode(final String nodePath, Watcher watcher) {
 OperationFuture<Stat> watchFuture = zkClient.exists(nodePath, watcher);
 Futures.addCallback(watchFuture, new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (state != State.CANCELLED) {
    becomeFollower();
   }
  }
  @Override
  public void onFailure(Throwable t) {
   LOG.warn("Exception while setting watch on node {}. Retry.", nodePath, t);
   runElection();
  }
 }, executor);
}

代码示例来源：origin: org.apache.twill/twill-zookeeper

/**
 * Watch for the given path until it exists.
 * @param zkClient The {@link ZKClient} to use.
 * @param path A ZooKeeper path to watch for existent.
 */
private static void watchExists(final ZKClient zkClient, final String path, final SettableFuture<String> completion) {
 Futures.addCallback(zkClient.exists(path, new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   if (!completion.isDone()) {
    watchExists(zkClient, path, completion);
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    completion.set(path);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   completion.setException(t);
  }
 });
}

代码示例来源：origin: apache/twill

/**
 * Watch for the given path until it exists.
 * @param zkClient The {@link ZKClient} to use.
 * @param path A ZooKeeper path to watch for existent.
 */
private static void watchExists(final ZKClient zkClient, final String path, final SettableFuture<String> completion) {
 Futures.addCallback(zkClient.exists(path, new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   if (!completion.isDone()) {
    watchExists(zkClient, path, completion);
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    completion.set(path);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   completion.setException(t);
  }
 });
}

代码示例来源：origin: org.apache.twill/twill-zookeeper

public static void watchDeleted(final ZKClient zkClient, final String path,
                final SettableFuture<String> completion) {
 Futures.addCallback(zkClient.exists(path, new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   if (!completion.isDone()) {
    if (event.getType() == Event.EventType.NodeDeleted) {
     completion.set(path);
    } else {
     watchDeleted(zkClient, path, completion);
    }
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result == null) {
    completion.set(path);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   completion.setException(t);
  }
 });
}

代码示例来源：origin: apache/twill

public static void watchDeleted(final ZKClient zkClient, final String path,
                final SettableFuture<String> completion) {
 Futures.addCallback(zkClient.exists(path, new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   if (!completion.isDone()) {
    if (event.getType() == Event.EventType.NodeDeleted) {
     completion.set(path);
    } else {
     watchDeleted(zkClient, path, completion);
    }
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result == null) {
    completion.set(path);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   completion.setException(t);
  }
 });
}

代码示例来源：origin: caskdata/cdap

/**
 * Start watching for changes in resources requirements.
 */
private void beginWatch(final Watcher watcher) {
 Futures.addCallback(zkClient.exists(CoordinationConstants.REQUIREMENTS_PATH, watcher),
           wrapCallback(new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    fetchAndProcessAllResources(watcher);
   }
   // If the node doesn't exists yet, that's ok, the watcher would handle it once it's created.
  }
  @Override
  public void onFailure(Throwable t) {
   // Something very wrong to have exists call failed.
   LOG.error("Failed to call exists on ZK node {}{}",
        zkClient.getConnectString(), CoordinationConstants.REQUIREMENTS_PATH, t);
   doNotifyFailed(t);
  }
 }), executor);
}

代码示例来源：origin: co.cask.cdap/cdap-common

/**
 * Start watching for changes in resources requirements.
 */
private void beginWatch(final Watcher watcher) {
 Futures.addCallback(zkClient.exists(CoordinationConstants.REQUIREMENTS_PATH, watcher),
           wrapCallback(new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    fetchAndProcessAllResources(watcher);
   }
   // If the node doesn't exists yet, that's ok, the watcher would handle it once it's created.
  }
  @Override
  public void onFailure(Throwable t) {
   // Something very wrong to have exists call failed.
   LOG.error("Failed to call exists on ZK node {}{}",
        zkClient.getConnectString(), CoordinationConstants.REQUIREMENTS_PATH, t);
   doNotifyFailed(t);
  }
 }), executor);
}

代码示例来源：origin: caskdata/cdap

private void existsAndWatch(final String name) {
 Futures.addCallback(zkClient.exists(getPath(name), new Watcher() {
  @Override
  public void process(WatchedEvent event) {

代码示例来源：origin: apache/twill

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return relayFuture(delegate.exists(getNamespacedPath(path), watcher), this.<Stat>createFuture(path));
}

代码示例来源：origin: org.apache.twill/twill-zookeeper

@Override
public OperationFuture<Stat> exists(String path, @Nullable Watcher watcher) {
 return relayFuture(delegate.exists(getNamespacedPath(path), watcher), this.<Stat>createFuture(path));
}

代码示例来源：origin: caskdata/cdap

/**
 * Starts watch for assignment changes when the node exists.
 *
 * @param serviceName Name of the service.
 */
private void watchAssignmentOnExists(final String serviceName) {
 final String zkPath = CoordinationConstants.ASSIGNMENTS_PATH + "/" + serviceName;
 Watcher watcher = wrapWatcher(new AssignmentWatcher(serviceName, EnumSet.of(Watcher.Event.EventType.NodeCreated)));
 Futures.addCallback(zkClient.exists(zkPath, watcher), wrapCallback(new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    watchAssignment(serviceName);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   LOG.error("Failed to call exists on ZK {}{}", zkClient.getConnectString(), zkPath, t);
   doNotifyFailed(t);
  }
 }), Threads.SAME_THREAD_EXECUTOR);
}

代码示例来源：origin: co.cask.cdap/cdap-common

/**
 * Starts watch for assignment changes when the node exists.
 *
 * @param serviceName Name of the service.
 */
private void watchAssignmentOnExists(final String serviceName) {
 final String zkPath = CoordinationConstants.ASSIGNMENTS_PATH + "/" + serviceName;
 Watcher watcher = wrapWatcher(new AssignmentWatcher(serviceName, EnumSet.of(Watcher.Event.EventType.NodeCreated)));
 Futures.addCallback(zkClient.exists(zkPath, watcher), wrapCallback(new FutureCallback<Stat>() {
  @Override
  public void onSuccess(Stat result) {
   if (result != null) {
    watchAssignment(serviceName);
   }
  }
  @Override
  public void onFailure(Throwable t) {
   LOG.error("Failed to call exists on ZK {}{}", zkClient.getConnectString(), zkPath, t);
   doNotifyFailed(t);
  }
 }), Threads.SAME_THREAD_EXECUTOR);
}

代码示例来源：origin: cdapio/cdap

public void init() throws InterruptedException {
 this.watcher = new ZKWatcher();
 try {
  LOG.info("Initializing SharedResourceCache.  Checking for parent znode {}", parentZnode);
  if (zookeeper.exists(parentZnode).get() == null) {
   // may be created in parallel by another instance
   // Also the child nodes are secure even without adding any ACLs to parent node.
   ZKOperations.ignoreError(zookeeper.create(parentZnode, null, CreateMode.PERSISTENT),
                KeeperException.NodeExistsException.class, null).get();
  }
 } catch (ExecutionException ee) {
  // recheck if already created
  throw Throwables.propagate(ee.getCause());
 }
 this.resources = reloadAll();
 listeners.notifyUpdate();
}

代码示例来源：origin: cdapio/cdap

private void existsAndWatch(final ProgramId serviceId, final SettableFuture<RouteConfig> oldSettableFuture) {
 Futures.addCallback(zkClient.exists(getZKPath(serviceId), new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   // If service name doesn't exist in the map, then don't rewatch it.
   if (!routeConfigMap.containsKey(serviceId)) {
    return;
   }
   if (event.getType() == Event.EventType.NodeCreated) {
    getAndWatchData(serviceId, SettableFuture.<RouteConfig>create(),
            oldSettableFuture, new ZKRouteWatcher(serviceId));
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(@Nullable Stat result) {
   if (result != null) {
    getAndWatchData(serviceId, SettableFuture.<RouteConfig>create(),
            oldSettableFuture, new ZKRouteWatcher(serviceId));
   }
  }
  @Override
  public void onFailure(Throwable t) {
   routeConfigMap.remove(serviceId);
   LOG.debug("Failed to check exists for property data for {}", serviceId, t);
  }
 });
}

代码示例来源：origin: co.cask.cdap/cdap-app-fabric

private void existsAndWatch(final ProgramId serviceId, final SettableFuture<RouteConfig> oldSettableFuture) {
 Futures.addCallback(zkClient.exists(getZKPath(serviceId), new Watcher() {
  @Override
  public void process(WatchedEvent event) {
   // If service name doesn't exist in the map, then don't rewatch it.
   if (!routeConfigMap.containsKey(serviceId)) {
    return;
   }
   if (event.getType() == Event.EventType.NodeCreated) {
    getAndWatchData(serviceId, SettableFuture.<RouteConfig>create(),
            oldSettableFuture, new ZKRouteWatcher(serviceId));
   }
  }
 }), new FutureCallback<Stat>() {
  @Override
  public void onSuccess(@Nullable Stat result) {
   if (result != null) {
    getAndWatchData(serviceId, SettableFuture.<RouteConfig>create(),
            oldSettableFuture, new ZKRouteWatcher(serviceId));
   }
  }
  @Override
  public void onFailure(Throwable t) {
   routeConfigMap.remove(serviceId);
   LOG.debug("Failed to check exists for property data for {}", serviceId, t);
  }
 });
}

代码示例来源：origin: caskdata/coopr

private void initializeCounter(Type type) {
  Stat stat = Futures.getUnchecked(zkClient.exists(type.path));
  if (stat == null) {
   Futures.getUnchecked(zkClient.create(type.path, Longs.toByteArray(startId), CreateMode.PERSISTENT, true));
  }
 }
}

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