Package org.elasticsearch.common.component

Class Lifecycle

java.lang.Object
org.elasticsearch.common.component.Lifecycle
public class Lifecycle extends Object
Lifecycle state. Allows the following transitions:
  • INITIALIZED -> STARTED, STOPPED, CLOSED
  • STARTED -> STOPPED
  • STOPPED -> STARTED, CLOSED
  • CLOSED ->

Also allows to stay in the same state. For example, when calling stop on a component, the following logic can be applied: 

 public void stop() {
  if (lifecycleState.moveToStopped() == false) {
      return;
  }
 // continue with stop logic
 }

NOTE: The Lifecycle class is thread-safe. It is also possible to prevent concurrent state transitions by locking on the Lifecycle object itself. This is typically useful when chaining multiple transitions.

Note, closed is only allowed to be called when stopped, so make sure to stop the component first. Here is how the logic can be applied. A lock of the lifecycleState object is taken so that another thread cannot move the state from STOPPED to STARTED before it has moved to CLOSED. 

 public void close() {
  synchronized (lifecycleState) {
      if (lifecycleState.started()) {
          stop();
      }
      if (lifecycleState.moveToClosed() == false) {
          return;
      }
  }
  // perform close logic here
 }