content: /**
   * Copyright (C) 2010-2016 eBusiness Information, Excilys Group
   * Copyright (C) 2016-2020 the AndroidAnnotations project
   *
   * Licensed 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.androidannotations.annotations;
  
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;
  
  /**
   * <p>
   * Should be used on method that must be run in a background thread.
   * </p>
   * <p>
   * The annotated method MUST return void and MAY contain parameters.
   * </p>
   * <p>
   * The generated code is based on
   * {@link org.androidannotations.api.BackgroundExecutor BackgroundExecutor}
   * methods.
   * </p>
   * 
   * <h2>Cancellation</h2>
   * <p>
   * Since 3.0, you're able to cancel a background task by calling
   * <code>BackgroundExecutor.cancelAll("id")</code> where "id" matches the
   * {@link #id()} value.
   * 
   * </p>
   * <blockquote>
   * 
   * <b>Example</b> :
   * 
   * <pre>
   * &#064;EBean
   * public class MyBean {
   * 	private static final String TASK_ID = &quot;task1&quot;;
   * 
   * 	&#064;Background(id = TASK_ID)
   * 	void launchTask() {
   * 		// ...
   * 	}
   * 
   * 	void stopTask() {
   * 		BackgroundExecutor.cancelAll(TASK_ID);
   * 	}
   * 
   * }
   * </pre>
   * 
   * </blockquote>
   * <p>
   * <b>Note</b>: Cancellation may or may not be successful. If the task wasn't
   * executed yet, it will be removed from the pool. But it could fail if task has
   * already completed, has already been cancelled, or could not be cancelled for
   * some other reason. See {@link java.util.concurrent.Future#cancel(boolean)
   * Future#cancel(boolean)} for more information.
   * </p>
   * 
   * <h2>Execution flow</h2>
   * <p>
   * By default, all tasks will be put in a
   * {@link java.util.concurrent.ScheduledThreadPoolExecutor
   * ScheduledThreadPoolExecutor} with a core pool size of
   * <code>2 * numberOfCpu</code>. Which means that background methods will be
   * executed in <b>PARALLEL</b>. You can change this by calling
   * <code>BackgroundExecutor.setExecutor(...)</code>.
   * </p>
   * <p>
   * If you want execute ALL background methods SEQUENTIALLY, the best way is to
   * change the executor of {@link org.androidannotations.api.BackgroundExecutor
   * BackgroundExecutor} to a
   * {@link java.util.concurrent.ScheduledThreadPoolExecutor
   * ScheduledThreadPoolExecutor} with a core pool size of <code>1</code>.
   * </p>
   * <p>
   * If you want execute some background methods SEQUENTIALLY, you should simply
   * use {@link #serial()} field. All task with the same serial key will be
   * executed sequentially.
   * </p>
   *
   * <blockquote>
   * 
   * <b>Example 1</b> (all tasks executed sequentially) :
   * 
   * <pre>
   * &#064;EBean
   * public class MyBean {
   * 
   * 	static {
   * 		BackgroundExecutor.setExecutor(Executors.newScheduledThreadPool(1));
   * 	}
   * 
   * 	private int i = 0;
   * 
   * 	void launchTasks() {
   * 		backgroundTask();
   * 		backgroundTask();
   * 		backgroundTask();
   * 	}
   * 
   * 	&#064;Background
   * 	void backgroundTask() {
   * 		Log.i(&quot;AA&quot;, &quot;i = &quot;, i++);
   * 	}
   * }
   * </pre>
   * 
   * <b>Example 2</b> (some tasks executed sequentially) :
   * 
   * <pre>
   * &#064;EBean
   * public class MyBean {
   * 
   * 	private int i = 0;
   * 
   * 	void launchTasks() {
   * 		backgroundTask();
   * 		backgroundTask();
   * 		backgroundTask();
   * 	}
   * 
   * 	&#064;Background(serial = &quot;sequence1&quot;)
   * 	void backgroundTask() {
   * 		Log.i(&quot;AA&quot;, &quot;i = &quot;, i++);
   * 	}
   * }
   * </pre>
   * 
   * </blockquote>
   * 
   * 
   * <h2>Delay</h2>
   * <p>
   * Sometimes you may want to delay execution of a background method. To do so,
   * you should use the {@link #delay()} field.
   * </p>
   * <b>Example</b> :
   *
   * <blockquote>
   * 
   * <pre>
   * &#064;EBean
   * public class MyBean {
   * 
   * 	&#064;Background(delay = 2000)
   * 	void backgroundTask() {
   * 		// ...
   * 	}
   * }
   * </pre>
   * 
   * </blockquote>
   * 
   * 
   * @see UiThread
   * @see org.androidannotations.api.BackgroundExecutor
   */
  @Retention(RetentionPolicy.CLASS)
  @Target(ElementType.METHOD)
  public @interface Background {
  	/**
  	 * Identifier for task cancellation.
  	 * 
  	 * To cancel all tasks having a specified background id:
  	 * 
  	 * <pre>
  	 * boolean mayInterruptIfRunning = true;
  	 * BackgroundExecutor.cancelAll(&quot;my_background_id&quot;, mayInterruptIfRunning);
  	 * </pre>
  	 * 
  	 * @return the task id for cancellation
  	 **/
  	String id() default "";
  
  	/**
  	 * Minimum delay, in milliseconds, before the background task is executed.
  	 *
  	 * @return the delay of the execution
  	 */
  	long delay() default 0;
  
  	/**
  	 * Serial execution group.
  	 * 
  	 * All background tasks having the same <code>serial</code> will be executed
  	 * sequentially.
  	 *
  	 * @return the serial execution group
  	 **/
  	String serial() default "";
  }
  