/*
* Licensed to Elastic Search and Shay Banon under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Elastic Search licenses this
* file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.common.component;
import org.elasticsearch.ElasticSearchIllegalStateException;
import org.elasticsearch.common.util.concurrent.ThreadSafe;
/**
* Lifecycle state. Allows the following transitions:
* <ul>
* <li>INITIALIZED -> STARTED, STOPPED, CLOSED</li>
* <li>STARTED -> STOPPED</li>
* <li>STOPPED -> STARTED, CLOSED</li>
* <li>CLOSED -> </li>
* </ul>
*
* <p>Also allows to stay in the same state. For example, when calling stop on a component, the
* following logic can be applied:
*
* <pre>
* public void stop() {
* if (!lifeccycleState.moveToStopped()) {
* return;
* }
* // continue with stop logic
* }
* </pre>
*
* <p>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:
*
* <pre>
* public void close() {
* if (lifecycleState.started()) {
* stop();
* }
* if (!lifecycleState.moveToClosed()) {
* return;
* }
* // perofrm close logic here
* }
* </pre>
*
* @author kimchy (Shay Banon)
*/
@ThreadSafe
public class Lifecycle {
public static enum State {
INITIALIZED,
STOPPED,
STARTED,
CLOSED
}
private volatile State state = State.INITIALIZED;
public State state() {
return this.state;
}
/**
* Returns <tt>true</tt> if the state is initialized.
*/
public boolean initialized() {
return state == State.INITIALIZED;
}
/**
* Returns <tt>true</tt> if the state is started.
*/
public boolean started() {
return state == State.STARTED;
}
/**
* Returns <tt>true</tt> if the state is stopped.
*/
public boolean stopped() {
return state == State.STOPPED;
}
/**
* Returns <tt>true</tt> if the state is closed.
*/
public boolean closed() {
return state == State.CLOSED;
}
public boolean stoppedOrClosed() {
Lifecycle.State state = this.state;
return state == State.STOPPED || state == State.CLOSED;
}
public boolean canMoveToStarted() throws ElasticSearchIllegalStateException {
State localState = this.state;
if (localState == State.INITIALIZED || localState == State.STOPPED) {
return true;
}
if (localState == State.STARTED) {
return false;
}
if (localState == State.CLOSED) {
throw new ElasticSearchIllegalStateException("Can't move to started state when closed");
}
throw new ElasticSearchIllegalStateException("Can't move to started with unknown state");
}
public boolean moveToStarted() throws ElasticSearchIllegalStateException {
State localState = this.state;
if (localState == State.INITIALIZED || localState == State.STOPPED) {
state = State.STARTED;
return true;
}
if (localState == State.STARTED) {
return false;
}
if (localState == State.CLOSED) {
throw new ElasticSearchIllegalStateException("Can't move to started state when closed");
}
throw new ElasticSearchIllegalStateException("Can't move to started with unknown state");
}
public boolean canMoveToStopped() throws ElasticSearchIllegalStateException {
State localState = state;
if (localState == State.STARTED) {
return true;
}
if (localState == State.INITIALIZED || localState == State.STOPPED) {
return false;
}
if (localState == State.CLOSED) {
throw new ElasticSearchIllegalStateException("Can't move to started state when closed");
}
throw new ElasticSearchIllegalStateException("Can't move to started with unknown state");
}
public boolean moveToStopped() throws ElasticSearchIllegalStateException {
State localState = state;
if (localState == State.STARTED) {
state = State.STOPPED;
return true;
}
if (localState == State.INITIALIZED || localState == State.STOPPED) {
return false;
}
if (localState == State.CLOSED) {
throw new ElasticSearchIllegalStateException("Can't move to started state when closed");
}
throw new ElasticSearchIllegalStateException("Can't move to started with unknown state");
}
public boolean canMoveToClosed() throws ElasticSearchIllegalStateException {
State localState = state;
if (localState == State.CLOSED) {
return false;
}
if (localState == State.STARTED) {
throw new ElasticSearchIllegalStateException("Can't move to closed before moving to stopped mode");
}
return true;
}
public boolean moveToClosed() throws ElasticSearchIllegalStateException {
State localState = state;
if (localState == State.CLOSED) {
return false;
}
if (localState == State.STARTED) {
throw new ElasticSearchIllegalStateException("Can't move to closed before moving to stopped mode");
}
state = State.CLOSED;
return true;
}
@Override public String toString() {
return state.toString();
}
}