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/*
This file is part of Subsonic.
Subsonic is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Subsonic is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Subsonic. If not, see <http://www.gnu.org/licenses/>.
Copyright 2009 (C) Sindre Mehus
*/
package github.daneren2005.dsub.util;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicBoolean;
import org.xmlpull.v1.XmlPullParserException;
import android.app.Activity;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.util.Log;
import github.daneren2005.dsub.R;
import github.daneren2005.dsub.view.ErrorDialog;
/**
* @author Sindre Mehus
*/
public abstract class BackgroundTask<T> implements ProgressListener {
private static final String TAG = BackgroundTask.class.getSimpleName();
private final Context context;
protected boolean cancelled = false;
protected Task task;
private static final int DEFAULT_CONCURRENCY = 5;
private static final Collection<Thread> threads = Collections.synchronizedCollection(new ArrayList<Thread>());
protected static final BlockingQueue<BackgroundTask.Task> queue = new LinkedBlockingQueue<BackgroundTask.Task>(10);
private static final Handler handler = new Handler();
public BackgroundTask(Context context) {
this.context = context;
if(threads.size() < DEFAULT_CONCURRENCY) {
for(int i = threads.size(); i < DEFAULT_CONCURRENCY; i++) {
Thread thread = new Thread(new TaskRunnable(), String.format("BackgroundTask_%d", i));
threads.add(thread);
thread.start();
}
}
}
public static void stopThreads() {
for(Thread thread: threads) {
thread.interrupt();
}
threads.clear();
queue.clear();
}
protected Activity getActivity() {
return (context instanceof Activity) ? ((Activity) context) : null;
}
protected Handler getHandler() {
return handler;
}
public abstract void execute();
protected abstract T doInBackground() throws Throwable;
protected abstract void done(T result);
protected void error(Throwable error) {
Log.w(TAG, "Got exception: " + error, error);
Activity activity = getActivity();
if(activity != null) {
new ErrorDialog(activity, getErrorMessage(error), true);
}
}
protected String getErrorMessage(Throwable error) {
if (error instanceof IOException && !Util.isNetworkConnected(context)) {
return context.getResources().getString(R.string.background_task_no_network);
}
if (error instanceof FileNotFoundException) {
return context.getResources().getString(R.string.background_task_not_found);
}
if (error instanceof IOException) {
return context.getResources().getString(R.string.background_task_network_error);
}
if (error instanceof XmlPullParserException) {
return context.getResources().getString(R.string.background_task_parse_error);
}
String message = error.getMessage();
if (message != null) {
return message;
}
return error.getClass().getSimpleName();
}
public void cancel() {
cancelled = true;
if(task != null) {
task.cancel();
}
}
protected boolean isCancelled() {
return cancelled;
}
@Override
public abstract void updateProgress(final String message);
@Override
public void updateProgress(int messageId) {
updateProgress(context.getResources().getString(messageId));
}
protected class Task {
private Thread thread;
private AtomicBoolean taskStart = new AtomicBoolean(true);
private void execute() throws Exception {
if(!taskStart.get()) {
return;
}
thread = Thread.currentThread();
try {
final T result = doInBackground();
if(isCancelled()) {
return;
}
handler.post(new Runnable() {
@Override
public void run() {
onDone(result);
}
});
} catch(InterruptedException interrupt) {
if(taskStart.get()) {
// Don't exit root thread if task cancelled
throw interrupt;
}
} catch(final Throwable t) {
if(isCancelled()) {
return;
}
handler.post(new Runnable() {
@Override
public void run() {
try {
onError(t);
} catch(Exception e) {
// Don't care
}
}
});
}
}
public void cancel() {
taskStart.set(false);
if(thread != null) {
thread.interrupt();
}
}
public void onDone(T result) {
done(result);
}
public void onError(Throwable t) {
error(t);
}
}
private class TaskRunnable implements Runnable {
private boolean running = true;
public TaskRunnable() {
}
@Override
public void run() {
Looper.prepare();
while(running) {
try {
Task task = queue.take();
task.execute();
} catch(InterruptedException stop) {
running = false;
threads.remove(Thread.currentThread());
} catch(Throwable t) {
Log.e(TAG, "Unexpected crash in BackgroundTask thread", t);
}
}
}
}
}
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