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213 lines (191 loc) · 6.45 KB
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/**
* Copyright (C) 2010-2013 eBusiness Information, Excilys Group
*
* 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.api;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class BackgroundExecutor {
private static Executor executor = Executors.newScheduledThreadPool(2 * Runtime.getRuntime().availableProcessors());
/*
* serialRunning is used as a lock in synchronized blocks for both
* serialRunning and serialQueues access
*/
/* Set of queueIds having a currently running task */
private static final Set<String> serialRunning = new HashSet<String>();
/* Tasks queues for each serial */
private static final Map<String, List<Task>> serialQueues = new HashMap<String, List<Task>>();
/**
* Execute a task after (at least) the given delay <strong>and</strong>
* after all tasks added with the same non-null <code>serial</code> (if any)
* have completed execution.
*
* @param runnable
* the task to execute
* @param delay
* the time from now to delay execution, in milliseconds
* @param serial
* the serial queue to use (<code>null</code> or <code>""</code>
* for no serial execution)
* @throws IllegalArgumentException
* if <code>delay</code> is strictly positive and the current
* executor does not support scheduling (if
* {@link #setExecutor(Executor)} has been called with such an
* executor)
*/
public static void execute(Runnable runnable, int delay, String serial) {
/* "" means null (a default annotation String value cannot be null) */
if (serial == null || serial.isEmpty()) {
if (delay > 0) {
/* no serial, but a delay: schedule the task */
if (!(executor instanceof ScheduledExecutorService)) {
throw new IllegalArgumentException("The executor set does not support scheduling");
}
((ScheduledExecutorService) executor).schedule(runnable, delay, TimeUnit.MILLISECONDS);
} else {
/* no serial, no delay: execute now */
executor.execute(runnable);
}
} else {
/* serial is defined, the delay is managed by Task */
Task task = new Task(runnable, delay, serial);
synchronized (serialRunning) {
if (serialRunning.contains(serial)) {
/* a task for this serial is already running, queue this one */
List<Task> queue = serialQueues.get(serial);
if (queue == null) {
/* the queue does not exist yet */
queue = new ArrayList<Task>();
serialQueues.put(serial, queue);
}
/* queue the task for later execution */
queue.add(task);
} else {
/* mark this serial as having a running task */
serialRunning.add(serial);
/* execute the task (a wrapper for runnable) now */
execute(task, delay); /* do not pass serial here */
}
}
}
}
/**
* Execute a task.
*
* Equivalent to {@link #execute(Runnable, int, String) execute(runnable, 0,
* null)}.
*
* @param runnable
* the task to execute
*/
public static void execute(Runnable runnable) {
execute(runnable, 0, null);
}
/**
* Execute a task after the given delay.
*
* Equivalent to {@link #execute(Runnable, int, String) execute(runnable,
* delay, null)}.
*
* @param runnable
* the task to execute
* @param delay
* the time from now to delay execution, in milliseconds
* @throws IllegalArgumentException
* if <code>delay</code> is strictly positive and the current
* executor does not support scheduling (if
* {@link #setExecutor(Executor)} has been called with such an
* executor)
*/
public static void execute(Runnable runnable, int delay) {
execute(runnable, delay, null);
}
/**
* Execute a task after all tasks added with the same non-null
* <code>serial</code> (if any) have completed execution.
*
* Equivalent to {@link #execute(Runnable, int, String) execute(runnable, 0,
* serial)}.
*
* @param runnable
* the task to execute
* @param serial
* the serial queue to use (<code>null</code> or <code>""</code>
* for no serial execution)
*/
public static void execute(Runnable runnable, String serial) {
execute(runnable, 0, serial);
}
/**
* Change the executor.
*
* Note that if the given executor is not a {@link ScheduledExecutorService}
* then executing a task after a delay will not be supported anymore.
*
* @param executor
* the new executor
*/
public static void setExecutor(Executor executor) {
BackgroundExecutor.executor = executor;
}
private static class Task implements Runnable {
Runnable runnable;
long targetTime; /* in milliseconds since epoch */
String serial;
Task(Runnable runnable, int delay, String serial) {
this.runnable = runnable;
if (delay > 0) {
targetTime = System.currentTimeMillis() + delay;
}
this.serial = serial;
}
@Override
public void run() {
try {
runnable.run();
} finally {
/* handle next tasks */
postExecute();
}
}
private void postExecute() {
synchronized (serialRunning) {
List<Task> queue = serialQueues.get(serial);
if (queue == null) {
/* no task is queue for this serial, mark it as not running */
serialRunning.remove(serial);
} else {
/* queue is not empty, retrieve the oldest queued task */
Task nextTask = queue.remove(0);
if (queue.isEmpty()) {
/* no more tasks in the queue */
serialQueues.remove(serial);
}
/* compute the remaining delay */
int delay = Math.max(0, (int) (nextTask.targetTime - System.currentTimeMillis()));
/* execute the next task */
execute(nextTask, delay); /* do not pass serial here */
}
}
}
}
}