Package org.elasticsearch.common.component

Class Lifecycle

java.lang.Object

org.elasticsearch.common.component.Lifecycle

public class Lifecycle
extends java.lang.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
 }
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Lifecycle.State

Constructor Summary

Constructors

Constructor	Description
Lifecycle()

Method Summary

Modifier and Type	Method	Description
boolean	canMoveToClosed()
boolean	canMoveToStarted()
boolean	canMoveToStopped()
boolean	closed()	Returns true if the state is closed.
boolean	initialized()	Returns true if the state is initialized.
boolean	moveToClosed()
boolean	moveToStarted()
boolean	moveToStopped()
boolean	started()	Returns true if the state is started.
Lifecycle.State	state()
boolean	stopped()	Returns true if the state is stopped.
boolean	stoppedOrClosed()
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

Lifecycle

public Lifecycle()

Method Details

state

public Lifecycle.State state()

initialized

public boolean initialized()

Returns true if the state is initialized.

started

public boolean started()

Returns true if the state is started.

stopped

public boolean stopped()

Returns true if the state is stopped.

closed

public boolean closed()

Returns true if the state is closed.

stoppedOrClosed

public boolean stoppedOrClosed()

canMoveToStarted

public boolean canMoveToStarted()
                         throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

moveToStarted

public boolean moveToStarted()
                      throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

canMoveToStopped

public boolean canMoveToStopped()
                         throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

moveToStopped

public boolean moveToStopped()
                      throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

canMoveToClosed

public boolean canMoveToClosed()
                        throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

moveToClosed

public boolean moveToClosed()
                     throws java.lang.IllegalStateException

Throws:

java.lang.IllegalStateException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object