001/*
002 * SonarQube
003 * Copyright (C) 2009-2017 SonarSource SA
004 * mailto:info AT sonarsource DOT com
005 *
006 * This program is free software; you can redistribute it and/or
007 * modify it under the terms of the GNU Lesser General Public
008 * License as published by the Free Software Foundation; either
009 * version 3 of the License, or (at your option) any later version.
010 *
011 * This program is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014 * Lesser General Public License for more details.
015 *
016 * You should have received a copy of the GNU Lesser General Public License
017 * along with this program; if not, write to the Free Software Foundation,
018 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
019 */
020package org.sonar.api;
021
022/**
023 * An interface which is implemented by classes annotated with {@link org.sonar.api.batch.ScannerSide ScannerSide},
024 * {@link org.sonar.api.server.ServerSide ServerSide} and/or {@link org.sonar.api.ce.ComputeEngineSide ComputeEngineSide}
025 * (referred to below as "component") that can be started and stopped.
026 * <p>
027 * The method {@link #start()} is called at the begin of the component lifecycle.
028 * It can be called again only after a call to {@link #stop()}. The {@link #stop()} method is called at the end of the
029 * component lifecycle, and can further be called after every {@link Startable#start()}.
030 * </p>
031 * <p>
032 * In the WebServer, a component is started once: either right when the WebServer is started if there is no migration,
033 * otherwise only after Database has been successfully migrated. It is stopped once when the WebServer is shutdown. Any
034 * exception thrown by method {@link #start()} will make the WebServer startup fail.
035 * </p>
036 * <p>
037 * In the Compute Engine, a component is started once when the Compute Engine is started and stopped once when the
038 * ComputeEngine is shut down. Any exception thrown by method {@link #start()} will make the Compute Engine startup fail.
039 * </p>
040 * <p>
041 * On Scanner side, the lifecycle of a component depends on the value of the {@link org.sonar.api.batch.InstantiationStrategy
042 * InstantiationStrategy} annotation.
043 * </p>
044 */
045public interface Startable {
046  /**
047   * Start this component. Called initially at the begin of the lifecycle. It can be called again after a stop.
048   */
049  void start();
050
051  /**
052   * Stop this component. Called near the end of the lifecycle. It can be called again after a further start.
053   */
054  void stop();
055}