The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 package org.mozilla.gecko.util;

 import android.os.Handler;

 import android.os.Looper;

 import java.util.concurrent.SynchronousQueue;

 final class GeckoBackgroundThread extends Thread {

     private static final String LOOPER_NAME = "GeckoBackgroundThread";

     // Guarded by 'this'.

     private static Handler sHandler = null;

     private SynchronousQueue<Handler> mHandlerQueue = new SynchronousQueue<Handler>();

     // Singleton, so private constructor.

     private GeckoBackgroundThread() {

         super();

     }

     @Override

     public void run() {

         setName(LOOPER_NAME);

         Looper.prepare();

         try {

             mHandlerQueue.put(new Handler());

         } catch (InterruptedException ie) {}

         Looper.loop();

     }

     // Get a Handler for a looper thread, or create one if it doesn't yet exist.

     /*package*/ static synchronized Handler getHandler() {

         if (sHandler == null) {

             GeckoBackgroundThread lt = new GeckoBackgroundThread();

             ThreadUtils.setBackgroundThread(lt);

             lt.start();

             try {

                 sHandler = lt.mHandlerQueue.take();

             } catch (InterruptedException ie) {}

         }

         return sHandler;

     }

     /*package*/ static void post(Runnable runnable) {

         Handler handler = getHandler();

         if (handler == null) {

             throw new IllegalStateException("No handler! Must have been interrupted. Not posting.");

         }

         handler.post(runnable);

     }

 }