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Elasticsearch subproject :server
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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;
/**
* 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()) {
* return;
* }
* // continue with stop logic
* }
*
*
* 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:
*
* public void close() {
* if (lifecycleState.started()) {
* stop();
* }
* if (!lifecycleState.moveToClosed()) {
* return;
* }
* // perform close logic here
* }
*
*/
public class Lifecycle {
public enum State {
INITIALIZED,
STOPPED,
STARTED,
CLOSED
}
private volatile State state = State.INITIALIZED;
public State state() {
return this.state;
}
/**
* Returns true if the state is initialized.
*/
public boolean initialized() {
return state == State.INITIALIZED;
}
/**
* Returns true if the state is started.
*/
public boolean started() {
return state == State.STARTED;
}
/**
* Returns true if the state is stopped.
*/
public boolean stopped() {
return state == State.STOPPED;
}
/**
* Returns true 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 IllegalStateException {
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 IllegalStateException("Can't move to started state when closed");
}
throw new IllegalStateException("Can't move to started with unknown state");
}
public boolean moveToStarted() throws IllegalStateException {
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 IllegalStateException("Can't move to started state when closed");
}
throw new IllegalStateException("Can't move to started with unknown state");
}
public boolean canMoveToStopped() throws IllegalStateException {
State localState = state;
if (localState == State.STARTED) {
return true;
}
if (localState == State.INITIALIZED || localState == State.STOPPED) {
return false;
}
if (localState == State.CLOSED) {
throw new IllegalStateException("Can't move to stopped state when closed");
}
throw new IllegalStateException("Can't move to stopped with unknown state");
}
public boolean moveToStopped() throws IllegalStateException {
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 IllegalStateException("Can't move to stopped state when closed");
}
throw new IllegalStateException("Can't move to stopped with unknown state");
}
public boolean canMoveToClosed() throws IllegalStateException {
State localState = state;
if (localState == State.CLOSED) {
return false;
}
if (localState == State.STARTED) {
throw new IllegalStateException("Can't move to closed before moving to stopped mode");
}
return true;
}
public boolean moveToClosed() throws IllegalStateException {
State localState = state;
if (localState == State.CLOSED) {
return false;
}
if (localState == State.STARTED) {
throw new IllegalStateException("Can't move to closed before moving to stopped mode");
}
state = State.CLOSED;
return true;
}
@Override
public String toString() {
return state.toString();
}
}