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Recipe: Persistent TTL Node

Description​

PersistentTtlNode is useful when you need to create a TTL node but don't want to keep it alive manually by periodically setting data - PersistentTtlNode does that for you. Further the keep-alive is done in a way that does not generate watch triggers on the parent node. It also provides similar guarantees that a Persistent Node does: the node attempts to stay present in ZooKeeper, even through connection and session interruptions.

Participating Classes​

  • PersistentNode
  • PersistentTtlNode

Creating a PersistentTtlNode​

// Parameters:
// client - client instance
// path path for the parent ZNode
// ttlMs max ttl for the node in milliseconds
// initData - initData for the node
public PersistentTtlNode(CuratorFramework client, String path, long ttlMs, byte[] initData);

General Usage​

PersistentTtlNode must be started:

node.start();

When you are through with the PersistentTtlNode instance, you should call close:

node.close();

... this will NOT delete the node immediately. The node will get deleted based on the ttl.

Error Handling​

PersistentTtlNode instances internally handle all error states recreating the node as necessary.