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Persistent Recursive Watcher

Note: PersistentWatcher requires ZooKeeper 3.6+.

Description

A managed persistent persistent watcher. The watch will be managed such that it stays set through connection lapses, etc.

Participating Classes

  • PersistentWatcher

Usage

Creating a PersistentWatcher

public PersistentWatcher(CuratorFramework client,
                               String basePath,
                               boolean recursive)

Parameters:
client - the client
basePath - path to set the watch on
recursive - ZooKeeper persistent watches can optionally be recursive

General Usage

The instance must be started by calling start(). Call close() when you want to remove the watch.

PersistentWatcher presents two listener types:

  • Listenable<Watcher> getListenable() - Use this to add watchers. These will behave in the same manner that watchers added via ZooKeeper.addWatch() behave.
  • Listenable<Runnable> getResetListenable() - The Runnables added with this get called once the Persistent Watcher has been successfully set (or reset after a connection partition).

Error Handling

PersistentWatcher instances internally monitor connection losses, etc. automatically resetting on reconnection.