package com.stxnext.management.android.ui.dependencies;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicInteger;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
/**
* <p>
* AsyncTaskEx enables proper and easy use of the UI thread. This class allows
* to perform background operations and publish results on the UI thread without
* having to manipulate threads and/or handlers.
* </p>
* <p>
* An asynchronous task is defined by a computation that runs on a background
* thread and whose result is published on the UI thread. An asynchronous task
* is defined by 3 generic types, called <code>Params</code>,
* <code>Progress</code> and <code>Result</code>, and 4 steps, called
* <code>begin</code>, <code>doInBackground</code>,
* <code>processProgress<code> and <code>end</code>.
* </p>
* <h2>Usage</h2>
* <p>
* AsyncTaskEx must be subclassed to be used. The subclass will override at
* least one method ({@link #doInBackground}), and most often will override a
* second one ({@link #onPostExecute}.)
* </p>
* <p>
* Here is an example of subclassing:
* </p>
*
* <pre class="prettyprint">
* private class DownloadFilesTask extends AsyncTaskEx<URL, Integer, Long> {
* protected Long doInBackground(URL... urls) {
* int count = urls.length;
* long totalSize = 0;
* for (int i = 0; i < count; i++) {
* totalSize += Downloader.downloadFile(urls[i]);
* publishProgress((int) ((i / (float) count) * 100));
* }
* return totalSize;
* }
*
* protected void onProgressUpdate(Integer... progress) {
* setProgressPercent(progress[0]);
* }
*
* protected void onPostExecute(Long result) {
* showDialog("Downloaded " + result + " bytes");
* }
* }
* </pre>
* <p>
* Once created, a task is executed very simply:
* </p>
*
* <pre class="prettyprint">
* new DownloadFilesTask().execute(url1, url2, url3);
* </pre>
*
* <h2>AsyncTaskEx's generic types</h2>
* <p>
* The three types used by an asynchronous task are the following:
* </p>
* <ol>
* <li><code>Params</code>, the type of the parameters sent to the task upon
* execution.</li>
* <li><code>Progress</code>, the type of the progress units published during
* the background computation.</li>
* <li><code>Result</code>, the type of the result of the background
* computation.</li>
* </ol>
* <p>
* Not all types are always used by am asynchronous task. To mark a type as
* unused, simply use the type {@link Void}:
* </p>
*
* <pre>
* private class MyTask extends AsyncTaskEx<Void, Void, Void) { ... }
* </pre>
*
* <h2>The 4 steps</h2>
* <p>
* When an asynchronous task is executed, the task goes through 4 steps:
* </p>
* <ol>
* <li>{@link #onPreExecute()}, invoked on the UI thread immediately after the
* task is executed. This step is normally used to setup the task, for instance
* by showing a progress bar in the user interface.</li>
* <li>{@link #doInBackground}, invoked on the background thread immediately
* after {@link #onPreExecute()} finishes executing. This step is used to
* perform background computation that can take a long time. The parameters of
* the asynchronous task are passed to this step. The result of the computation
* must be returned by this step and will be passed back to the last step. This
* step can also use {@link #publishProgress} to publish one or more units of
* progress. These values are published on the UI thread, in the
* {@link #onProgressUpdate} step.</li>
* <li>{@link #onProgressUpdate}, invoked on the UI thread after a call to
* {@link #publishProgress}. The timing of the execution is undefined. This
* method is used to display any form of progress in the user interface while
* the background computation is still executing. For instance, it can be used
* to animate a progress bar or show logs in a text field.</li>
* <li>{@link #onPostExecute}, invoked on the UI thread after the background
* computation finishes. The result of the background computation is passed to
* this step as a parameter.</li>
* </ol>
* <h2>Threading rules</h2>
* <p>
* There are a few threading rules that must be followed for this class to work
* properly:
* </p>
* <ul>
* <li>The task instance must be created on the UI thread.</li>
* <li>{@link #execute} must be invoked on the UI thread.</li>
* <li>Do not call {@link #onPreExecute()}, {@link #onPostExecute},
* {@link #doInBackground}, {@link #onProgressUpdate} manually.</li>
* <li>The task can be executed only once (an exception will be thrown if a
* second execution is attempted.)</li>
* </ul>
*/
public abstract class AsyncTaskEx<Params, Progress, Result> {
private static final String LOG_TAG = "AsyncTaskEx";
private static final int CORE_POOL_SIZE = 3;
private static final int MAXIMUM_POOL_SIZE = 10;
private static final int KEEP_ALIVE = 15;
private static final LinkedBlockingQueue<Runnable> sWorkQueue =
new LinkedBlockingQueue<Runnable>();
private static final ThreadFactory sThreadFactory = new ThreadFactory() {
private final AtomicInteger mCount = new AtomicInteger(1);
public Thread newThread(Runnable r) {
return new Thread(r, "AsyncTaskEx #" + mCount.getAndIncrement());
}
};
private static final ThreadPoolExecutor sExecutor = new ThreadPoolExecutor(CORE_POOL_SIZE,
MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, sWorkQueue, sThreadFactory);
private static final int MESSAGE_POST_RESULT = 0x1;
private static final int MESSAGE_POST_PROGRESS = 0x2;
private static final int MESSAGE_POST_CANCEL = 0x3;
private static final InternalHandler sHandler = new InternalHandler();
private final WorkerRunnable<Params, Result> mWorker;
private final FutureTask<Result> mFuture;
private volatile Status mStatus = Status.PENDING;
/**
* Indicates the current status of the task. Each status will be set only
* once during the lifetime of a task.
*/
public enum Status {
/**
* Indicates that the task has not been executed yet.
*/
PENDING,
/**
* Indicates that the task is running.
*/
RUNNING,
/**
* Indicates that {@link AsyncTaskEx#onPostExecute} has finished.
*/
FINISHED,
}
public static void clearQueue() {
sWorkQueue.clear();
}
/**
* Creates a new asynchronous task. This constructor must be invoked on the
* UI thread.
*/
//private int priority;
public AsyncTaskEx(final int priority) {
//this.priority = priority;
mWorker = new WorkerRunnable<Params, Result>() {
public Result call() throws Exception {
//Process.setThreadPriority(priority);
Thread.currentThread().setPriority(priority);
return doInBackground(mParams);
}
};
mFuture = new FutureTask<Result>(mWorker) {
@SuppressWarnings("unchecked")
@Override
protected void done() {
Message message;
Result result = null;
try {
result = get();
} catch (InterruptedException e) {
android.util.Log.w(LOG_TAG, e);
} catch (ExecutionException e) {
throw new RuntimeException("An error occured while executing doInBackground()",
e.getCause());
} catch (CancellationException e) {
message = sHandler.obtainMessage(MESSAGE_POST_CANCEL,
new AsyncTaskExResult<Result>(AsyncTaskEx.this, (Result[]) null));
message.sendToTarget();
return;
} catch (Throwable t) {
throw new RuntimeException("An error occured while executing "
+ "doInBackground()", t);
}
message = sHandler.obtainMessage(MESSAGE_POST_RESULT,
new AsyncTaskExResult<Result>(AsyncTaskEx.this, result));
message.sendToTarget();
}
};
}
public AsyncTaskEx() {
mWorker = new WorkerRunnable<Params, Result>() {
public Result call() throws Exception {
//Process.setThreadPriority(Process.THREAD_PRIORITY_URGENT_AUDIO);
Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
return doInBackground(mParams);
}
};
mFuture = new FutureTask<Result>(mWorker) {
@SuppressWarnings("unchecked")
@Override
protected void done() {
Message message;
Result result = null;
try {
result = get();
} catch (InterruptedException e) {
android.util.Log.w(LOG_TAG, e);
} catch (ExecutionException e) {
throw new RuntimeException("An error occured while executing doInBackground()",
e.getCause());
} catch (CancellationException e) {
message = sHandler.obtainMessage(MESSAGE_POST_CANCEL,
new AsyncTaskExResult<Result>(AsyncTaskEx.this, (Result[]) null));
message.sendToTarget();
return;
} catch (Throwable t) {
throw new RuntimeException("An error occured while executing "
+ "doInBackground()", t);
}
message = sHandler.obtainMessage(MESSAGE_POST_RESULT,
new AsyncTaskExResult<Result>(AsyncTaskEx.this, result));
message.sendToTarget();
}
};
}
/**
* Returns the current status of this task.
*
* @return The current status.
*/
public final Status getStatus() {
return mStatus;
}
/**
* Override this method to perform a computation on a background thread. The
* specified parameters are the parameters passed to {@link #execute} by the
* caller of this task. This method can call {@link #publishProgress} to
* publish updates on the UI thread.
*
* @param params The parameters of the task.
* @return A result, defined by the subclass of this task.
* @see #onPreExecute()
* @see #onPostExecute
* @see #publishProgress
*/
protected abstract Result doInBackground(Params... params);
/**
* Runs on the UI thread before {@link #doInBackground}.
*
* @see #onPostExecute
* @see #doInBackground
*/
protected void onPreExecute() {
}
/**
* Runs on the UI thread after {@link #doInBackground}. The specified result
* is the value returned by {@link #doInBackground} or null if the task was
* cancelled or an exception occured.
*
* @param result The result of the operation computed by
* {@link #doInBackground}.
* @see #onPreExecute
* @see #doInBackground
*/
protected void onPostExecute(Result result) {
}
/**
* Runs on the UI thread after {@link #publishProgress} is invoked. The
* specified values are the values passed to {@link #publishProgress}.
*
* @param values The values indicating progress.
* @see #publishProgress
* @see #doInBackground
*/
protected void onProgressUpdate(Progress... values) {
}
/**
* Runs on the UI thread after {@link #cancel(boolean)} is invoked.
*
* @see #cancel(boolean)
* @see #isCancelled()
*/
protected void onCancelled() {
}
/**
* Returns <tt>true</tt> if this task was cancelled before it completed
* normally.
*
* @return <tt>true</tt> if task was cancelled before it completed
* @see #cancel(boolean)
*/
public final boolean isCancelled() {
return mFuture.isCancelled();
}
/**
* Attempts to cancel execution of this task. This attempt will fail if the
* task has already completed, already been cancelled, or could not be
* cancelled for some other reason. If successful, and this task has not
* started when <tt>cancel</tt> is called, this task should never run. If
* the task has already started, then the <tt>mayInterruptIfRunning</tt>
* parameter determines whether the thread executing this task should be
* interrupted in an attempt to stop the task.
*
* @param mayInterruptIfRunning <tt>true</tt> if the thread executing this
* task should be interrupted; otherwise, in-progress tasks are
* allowed to complete.
* @return <tt>false</tt> if the task could not be cancelled, typically
* because it has already completed normally; <tt>true</tt>
* otherwise
* @see #isCancelled()
* @see #onCancelled()
*/
public final boolean cancel(boolean mayInterruptIfRunning) {
return mFuture.cancel(mayInterruptIfRunning);
}
/**
* Waits if necessary for the computation to complete, and then retrieves
* its result.
*
* @return The computed result.
* @throws CancellationException If the computation was cancelled.
* @throws ExecutionException If the computation threw an exception.
* @throws InterruptedException If the current thread was interrupted while
* waiting.
*/
public final Result get() throws InterruptedException, ExecutionException {
return mFuture.get();
}
/**
* Waits if necessary for at most the given time for the computation to
* complete, and then retrieves its result.
*
* @param timeout Time to wait before cancelling the operation.
* @param unit The time unit for the timeout.
* @return The computed result.
* @throws CancellationException If the computation was cancelled.
* @throws ExecutionException If the computation threw an exception.
* @throws InterruptedException If the current thread was interrupted while
* waiting.
* @throws TimeoutException If the wait timed out.
*/
public final Result get(long timeout, TimeUnit unit) throws InterruptedException,
ExecutionException, TimeoutException {
return mFuture.get(timeout, unit);
}
/**
* Executes the task with the specified parameters. The task returns itself
* (this) so that the caller can keep a reference to it. This method must be
* invoked on the UI thread.
*
* @param params The parameters of the task.
* @return This instance of AsyncTaskEx.
* @throws IllegalStateException If {@link #getStatus()} returns either
* {@link AsyncTaskEx.Status#RUNNING} or
* {@link AsyncTaskEx.Status#FINISHED}.
*/
public final AsyncTaskEx<Params, Progress, Result> execute(Params... params) {
if (mStatus != Status.PENDING) {
switch (mStatus) {
case RUNNING:
throw new IllegalStateException("Cannot execute task:"
+ " the task is already running.");
case FINISHED:
throw new IllegalStateException("Cannot execute task:"
+ " the task has already been executed "
+ "(a task can be executed only once)");
}
}
mStatus = Status.RUNNING;
onPreExecute();
mWorker.mParams = params;
sExecutor.execute(mFuture);
return this;
}
/**
* This method can be invoked from {@link #doInBackground} to publish
* updates on the UI thread while the background computation is still
* running. Each call to this method will trigger the execution of
* {@link #onProgressUpdate} on the UI thread.
*
* @param values The progress values to update the UI with.
* @see #onProgressUpdate
* @see #doInBackground
*/
protected final void publishProgress(Progress... values) {
sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
new AsyncTaskExResult<Progress>(this, values)).sendToTarget();
}
private void finish(Result result) {
onPostExecute(result);
mStatus = Status.FINISHED;
}
private static class InternalHandler extends Handler {
@SuppressWarnings({
"unchecked", "rawtypes"
})
@Override
public void handleMessage(Message msg) {
AsyncTaskExResult result = (AsyncTaskExResult) msg.obj;
switch (msg.what) {
case MESSAGE_POST_RESULT:
// There is only one result
result.mTask.finish(result.mData[0]);
break;
case MESSAGE_POST_PROGRESS:
result.mTask.onProgressUpdate(result.mData);
break;
case MESSAGE_POST_CANCEL:
result.mTask.onCancelled();
break;
}
}
}
private static abstract class WorkerRunnable<Params, Result> implements Callable<Result> {
Params[] mParams;
}
@SuppressWarnings({
"rawtypes"
})
private static class AsyncTaskExResult<Data> {
final AsyncTaskEx mTask;
final Data[] mData;
AsyncTaskExResult(AsyncTaskEx task, Data... data) {
mTask = task;
mData = data;
}
}
}