michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.util;
michael@0: 
michael@0: import android.os.Handler;
michael@0: import android.os.Looper;
michael@0: 
michael@0: import java.util.concurrent.SynchronousQueue;
michael@0: 
michael@0: final class GeckoBackgroundThread extends Thread {
michael@0:     private static final String LOOPER_NAME = "GeckoBackgroundThread";
michael@0: 
michael@0:     // Guarded by 'this'.
michael@0:     private static Handler sHandler = null;
michael@0:     private SynchronousQueue<Handler> mHandlerQueue = new SynchronousQueue<Handler>();
michael@0: 
michael@0:     // Singleton, so private constructor.
michael@0:     private GeckoBackgroundThread() {
michael@0:         super();
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void run() {
michael@0:         setName(LOOPER_NAME);
michael@0:         Looper.prepare();
michael@0:         try {
michael@0:             mHandlerQueue.put(new Handler());
michael@0:         } catch (InterruptedException ie) {}
michael@0: 
michael@0:         Looper.loop();
michael@0:     }
michael@0: 
michael@0:     // Get a Handler for a looper thread, or create one if it doesn't yet exist.
michael@0:     /*package*/ static synchronized Handler getHandler() {
michael@0:         if (sHandler == null) {
michael@0:             GeckoBackgroundThread lt = new GeckoBackgroundThread();
michael@0:             ThreadUtils.setBackgroundThread(lt);
michael@0:             lt.start();
michael@0:             try {
michael@0:                 sHandler = lt.mHandlerQueue.take();
michael@0:             } catch (InterruptedException ie) {}
michael@0:         }
michael@0:         return sHandler;
michael@0:     }
michael@0: 
michael@0:     /*package*/ static void post(Runnable runnable) {
michael@0:         Handler handler = getHandler();
michael@0:         if (handler == null) {
michael@0:             throw new IllegalStateException("No handler! Must have been interrupted. Not posting.");
michael@0:         }
michael@0:         handler.post(runnable);
michael@0:     }
michael@0: }