Field Detail

• LOG

  protected static final org.apache.commons.logging.Log LOG

• node

  protected final String node

  Path of node being tracked

• abortable

  protected final Abortable abortable

  Used to abort if a fatal error occurs

Constructor Detail

• ZooKeeperNodeTracker

  public ZooKeeperNodeTracker(ZooKeeperWatcher watcher,
                      String node,
                      Abortable abortable)

  Constructs a new ZK node tracker.

  After construction, use start() to kick off tracking.

  Parameters:

  watcher -

  node -

  abortable -

Method Detail

• start

  public void start()

  Starts the tracking of the node in ZooKeeper.

  Use blockUntilAvailable() to block until the node is available or getData(boolean) to get the data of the node if it is available.

• stop

  public void stop()

• blockUntilAvailable

  public byte[] blockUntilAvailable()
                             throws InterruptedException

  Gets the data of the node, blocking until the node is available.

  Returns:

  data of the node

  Throws:

  InterruptedException - if the waiting thread is interrupted

• blockUntilAvailable

  public byte[] blockUntilAvailable(long timeout,
                           boolean refresh)
                             throws InterruptedException

  Gets the data of the node, blocking until the node is available or the specified timeout has elapsed.

  Parameters:

  timeout - maximum time to wait for the node data to be available, n milliseconds. Pass 0 for no timeout.

  Returns:

  data of the node

  Throws:

  InterruptedException - if the waiting thread is interrupted

• getData

  public byte[] getData(boolean refresh)

  Gets the data of the node.

  If the node is currently available, the most up-to-date known version of the data is returned. If the node is not currently available, null is returned.

  Parameters:

  refresh - whether to refresh the data by calling ZK directly.

  Returns:

  data of the node, null if unavailable

• getNode

  public String getNode()

• nodeCreated

  public void nodeCreated(String path)

  Description copied from class: ZooKeeperListener
  Called when a new node has been created.

  Overrides:

  nodeCreated in class ZooKeeperListener

  Parameters:

  path - full path of the new node

• nodeDeleted

  public void nodeDeleted(String path)

  Description copied from class: ZooKeeperListener
  Called when a node has been deleted

  Overrides:

  nodeDeleted in class ZooKeeperListener

  Parameters:

  path - full path of the deleted node

• nodeDataChanged

  public void nodeDataChanged(String path)

  Description copied from class: ZooKeeperListener
  Called when an existing node has changed data.

  Overrides:

  nodeDataChanged in class ZooKeeperListener

  Parameters:

  path - full path of the updated node

• checkIfBaseNodeAvailable

  public boolean checkIfBaseNodeAvailable()

  Checks if the baseznode set as per the property 'zookeeper.znode.parent' exists.

  Returns:

  true if baseznode exists. false if doesnot exists.

• toString

  public String toString()

  Overrides:

  toString in class Object