package com.ccxt.whl.video.util;
import java.util.ArrayDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.concurrent.LinkedBlockingDeque;
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.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.os.Handler;
import android.os.Message;
import android.os.Process;
public abstract class AsyncTask<Params, Progress, Result> {
private static final String LOG_TAG = "AsyncTask";
private static final int CORE_POOL_SIZE = 5;
private static final int MAXIMUM_POOL_SIZE = 128;
private static final int KEEP_ALIVE = 1;
private static final ThreadFactory sThreadFactory = new ThreadFactory() {
private final AtomicInteger mCount = new AtomicInteger(1);
@Override
public Thread newThread(Runnable r) {
return new Thread(r, "AsyncTask #" + mCount.getAndIncrement());
}
};
@SuppressLint("NewApi")
private static final BlockingQueue<Runnable> sPoolWorkQueue = new LinkedBlockingDeque<Runnable>(
10);
/**
* An {@link java.util.concurrent.Executor} that can be used to execute
* tasks in parallel.
*/
public static final Executor THREAD_POOL_EXECUTOR = new ThreadPoolExecutor(
CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS,
sPoolWorkQueue, sThreadFactory,
new ThreadPoolExecutor.DiscardOldestPolicy());
/**
* An {@link java.util.concurrent.Executor} that executes tasks one at a
* time in serial order. This serialization is global to a particular
* process.
*/
public static final Executor SERIAL_EXECUTOR = Utils.hasHoneycomb() ? new SerialExecutor()
: Executors.newSingleThreadExecutor(sThreadFactory);
public static final Executor DUAL_THREAD_EXECUTOR = Executors
.newFixedThreadPool(2, sThreadFactory);
private static final int MESSAGE_POST_RESULT = 0x1;
private static final int MESSAGE_POST_PROGRESS = 0x2;
private static final InternalHandler sHandler = new InternalHandler();
private static volatile Executor sDefaultExecutor = SERIAL_EXECUTOR;
private final WorkerRunnable<Params, Result> mWorker;
private final FutureTask<Result> mFuture;
private volatile Status mStatus = Status.PENDING;
private final AtomicBoolean mCancelled = new AtomicBoolean();
private final AtomicBoolean mTaskInvoked = new AtomicBoolean();
@TargetApi(11)
private static class SerialExecutor implements Executor {
final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();
Runnable mActive;
public synchronized void execute(final Runnable r) {
mTasks.offer(new Runnable() {
public void run() {
try {
r.run();
} finally {
scheduleNext();
}
}
});
if (mActive == null) {
scheduleNext();
}
}
protected synchronized void scheduleNext() {
if ((mActive = mTasks.poll()) != null) {
THREAD_POOL_EXECUTOR.execute(mActive);
}
}
}
/**
* 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 AsyncTask#onPostExecute} has finished.
*/
FINISHED,
}
/** @hide Used to force static handler to be created. */
public static void init() {
sHandler.getLooper();
}
/** @hide */
public static void setDefaultExecutor(Executor exec) {
sDefaultExecutor = exec;
}
/**
* Creates a new asynchronous task. This constructor must be invoked on the
* UI thread.
*/
public AsyncTask() {
mWorker = new WorkerRunnable<Params, Result>() {
public Result call() throws Exception {
mTaskInvoked.set(true);
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
// noinspection unchecked
return postResult(doInBackground(mParams));
}
};
mFuture = new FutureTask<Result>(mWorker) {
@Override
protected void done() {
try {
postResultIfNotInvoked(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) {
postResultIfNotInvoked(null);
}
}
};
}
private void postResultIfNotInvoked(Result result) {
final boolean wasTaskInvoked = mTaskInvoked.get();
if (!wasTaskInvoked) {
postResult(result);
}
}
private Result postResult(Result result) {
@SuppressWarnings("unchecked")
Message message = sHandler.obtainMessage(MESSAGE_POST_RESULT,
new AsyncTaskResult<Result>(this, result));
message.sendToTarget();
return result;
}
/**
* 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() {
}
/**
* <p>
* Runs on the UI thread after {@link #doInBackground}. The specified result
* is the value returned by {@link #doInBackground}.
* </p>
*
* <p>
* This method won't be invoked if the task was cancelled.
* </p>
*
* @param result
* The result of the operation computed by
* {@link #doInBackground}.
*
* @see #onPreExecute
* @see #doInBackground
* @see #onCancelled(Object)
*/
@SuppressWarnings({ "UnusedDeclaration" })
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
*/
@SuppressWarnings({ "UnusedDeclaration" })
protected void onProgressUpdate(Progress... values) {
}
/**
* <p>
* Runs on the UI thread after {@link #cancel(boolean)} is invoked and
* {@link #doInBackground(Object[])} has finished.
* </p>
*
* <p>
* The default implementation simply invokes {@link #onCancelled()} and
* ignores the result. If you write your own implementation, do not call
* <code>super.onCancelled(result)</code>.
* </p>
*
* @param result
* The result, if any, computed in
* {@link #doInBackground(Object[])}, can be null
*
* @see #cancel(boolean)
* @see #isCancelled()
*/
@SuppressWarnings({ "UnusedParameters" })
protected void onCancelled(Result result) {
onCancelled();
}
/**
* <p>
* Applications should preferably override {@link #onCancelled(Object)}.
* This method is invoked by the default implementation of
* {@link #onCancelled(Object)}.
* </p>
*
* <p>
* Runs on the UI thread after {@link #cancel(boolean)} is invoked and
* {@link #doInBackground(Object[])} has finished.
* </p>
*
* @see #onCancelled(Object)
* @see #cancel(boolean)
* @see #isCancelled()
*/
protected void onCancelled() {
}
/**
* Returns <tt>true</tt> if this task was cancelled before it completed
* normally. If you are calling {@link #cancel(boolean)} on the task, the
* value returned by this method should be checked periodically from
* {@link #doInBackground(Object[])} to end the task as soon as possible.
*
* @return <tt>true</tt> if task was cancelled before it completed
*
* @see #cancel(boolean)
*/
public final boolean isCancelled() {
return mCancelled.get();
}
/**
* <p>
* 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.
* </p>
*
* <p>
* Calling this method will result in {@link #onCancelled(Object)} being
* invoked on the UI thread after {@link #doInBackground(Object[])} returns.
* Calling this method guarantees that {@link #onPostExecute(Object)} is
* never invoked. After invoking this method, you should check the value
* returned by {@link #isCancelled()} periodically from
* {@link #doInBackground(Object[])} to finish the task as early as
* possible.
* </p>
*
* @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(Object)
*/
public final boolean cancel(boolean mayInterruptIfRunning) {
mCancelled.set(true);
return mFuture.cancel(mayInterruptIfRunning);
}
/**
* Waits if necessary for the computation to complete, and then retrieves
* its result.
*
* @return The computed result.
*
* @throws java.util.concurrent.CancellationException
* If the computation was cancelled.
* @throws java.util.concurrent.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 java.util.concurrent.CancellationException
* If the computation was cancelled.
* @throws java.util.concurrent.ExecutionException
* If the computation threw an exception.
* @throws InterruptedException
* If the current thread was interrupted while waiting.
* @throws java.util.concurrent.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.
*
* <p>
* Note: this function schedules the task on a queue for a single background
* thread or pool of threads depending on the platform version. When first
* introduced, AsyncTasks were executed serially on a single background
* thread. Starting with {@link android.os.Build.VERSION_CODES#DONUT}, this
* was changed to a pool of threads allowing multiple tasks to operate in
* parallel. Starting {@link android.os.Build.VERSION_CODES#HONEYCOMB},
* tasks are back to being executed on a single thread to avoid common
* application errors caused by parallel execution. If you truly want
* parallel execution, you can use the {@link #executeOnExecutor} version of
* this method with {@link #THREAD_POOL_EXECUTOR}; however, see commentary
* there for warnings on its use.
*
* <p>
* This method must be invoked on the UI thread.
*
* @param params
* The parameters of the task.
*
* @return This instance of AsyncTask.
*
* @throws IllegalStateException
* If {@link #getStatus()} returns either
* {@link AsyncTask.Status#RUNNING} or
* {@link AsyncTask.Status#FINISHED}.
*
* @see #executeOnExecutor(java.util.concurrent.Executor, Object[])
* @see #execute(Runnable)
*/
public final AsyncTask<Params, Progress, Result> execute(Params... params) {
return executeOnExecutor(sDefaultExecutor, params);
}
/**
* Executes the task with the specified parameters. The task returns itself
* (this) so that the caller can keep a reference to it.
*
* <p>
* This method is typically used with {@link #THREAD_POOL_EXECUTOR} to allow
* multiple tasks to run in parallel on a pool of threads managed by
* AsyncTask, however you can also use your own
* {@link java.util.concurrent.Executor} for custom behavior.
*
* <p>
* <em>Warning:</em> Allowing multiple tasks to run in parallel from a
* thread pool is generally <em>not</em> what one wants, because the order
* of their operation is not defined. For example, if these tasks are used
* to modify any state in common (such as writing a file due to a button
* click), there are no guarantees on the order of the modifications.
* Without careful work it is possible in rare cases for the newer version
* of the data to be over-written by an older one, leading to obscure data
* loss and stability issues. Such changes are best executed in serial; to
* guarantee such work is serialized regardless of platform version you can
* use this function with {@link #SERIAL_EXECUTOR}.
*
* <p>
* This method must be invoked on the UI thread.
*
* @param exec
* The executor to use. {@link #THREAD_POOL_EXECUTOR} is
* available as a convenient process-wide thread pool for tasks
* that are loosely coupled.
* @param params
* The parameters of the task.
*
* @return This instance of AsyncTask.
*
* @throws IllegalStateException
* If {@link #getStatus()} returns either
* {@link AsyncTask.Status#RUNNING} or
* {@link AsyncTask.Status#FINISHED}.
*
* @see #execute(Object[])
*/
public final AsyncTask<Params, Progress, Result> executeOnExecutor(
Executor exec, 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;
exec.execute(mFuture);
return this;
}
/**
* Convenience version of {@link #execute(Object...)} for use with a simple
* Runnable object. See {@link #execute(Object[])} for more information on
* the order of execution.
*
* @see #execute(Object[])
* @see #executeOnExecutor(java.util.concurrent.Executor, Object[])
*/
public static void execute(Runnable runnable) {
sDefaultExecutor.execute(runnable);
}
/**
* 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.
*
* {@link #onProgressUpdate} will note be called if the task has been
* canceled.
*
* @param values
* The progress values to update the UI with.
*
* @see #onProgressUpdate
* @see #doInBackground
*/
protected final void publishProgress(Progress... values) {
if (!isCancelled()) {
sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
new AsyncTaskResult<Progress>(this, values)).sendToTarget();
}
}
private void finish(Result result) {
if (isCancelled()) {
onCancelled(result);
} else {
onPostExecute(result);
}
mStatus = Status.FINISHED;
}
private static class InternalHandler extends Handler {
@SuppressWarnings({ "unchecked", "RawUseOfParameterizedType" })
@Override
public void handleMessage(Message msg) {
AsyncTaskResult result = (AsyncTaskResult) 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;
}
}
}
private static abstract class WorkerRunnable<Params, Result> implements
Callable<Result> {
Params[] mParams;
}
@SuppressWarnings({ "RawUseOfParameterizedType" })
private static class AsyncTaskResult<Data> {
final AsyncTask mTask;
final Data[] mData;
AsyncTaskResult(AsyncTask task, Data... data) {
mTask = task;
mData = data;
}
}
}