make Looper, Handler, and MessageQueue work properly

this for example makes Unity apps not steal the main thread,
hanging Gtk.

src/api-impl/android/os/HandlerThread.java

@@ -1,19 +1,149 @@
+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package android.os;
 
+/**
+ * Handy class for starting a new thread that has a looper. The looper can then be
+ * used to create handler classes. Note that start() must still be called.
+ */
 public class HandlerThread extends Thread {
-	String name;
-
-	public HandlerThread() {}
+	int mPriority;
+	int mTid = -1;
+	Looper mLooper;
 
 	public HandlerThread(String name) {
-		this.name = name;
+		super(name);
+		mPriority = Process.THREAD_PRIORITY_DEFAULT;
 	}
 
-	public void start() {
-		// if(name.equals("FlurryAgent")) { return; }
+	/**
+	 * Constructs a HandlerThread.
+	 * @param name
+	 * @param priority The priority to run the thread at. The value supplied must be from
+	 * {@link android.os.Process} and not from java.lang.Thread.
+	 */
+	public HandlerThread(String name, int priority) {
+		super(name);
+		mPriority = priority;
 	}
 
+	/**
+	 * Call back method that can be explicitly overridden if needed to execute some
+	 * setup before Looper loops.
+	 */
+	protected void onLooperPrepared() {
+	}
+
+	@Override
+	public void run() {
+		mTid = Process.myTid();
+		Looper.prepare();
+		synchronized (this) {
+			mLooper = Looper.myLooper();
+			notifyAll();
+		}
+		Process.setThreadPriority(mPriority);
+		onLooperPrepared();
+		Looper.loop();
+		mTid = -1;
+	}
+
+	/**
+	 * This method returns the Looper associated with this thread. If this thread not been started
+	 * or for any reason is isAlive() returns false, this method will return null. If this thread
+	 * has been started, this method will block until the looper has been initialized.
+	 * @return The looper.
+	 */
 	public Looper getLooper() {
-		return new Looper();
+		if (!isAlive()) {
+			return null;
+		}
+
+		// If the thread has been started, wait until the looper has been created.
+		synchronized (this) {
+			while (isAlive() && mLooper == null) {
+				try {
+					wait();
+				} catch (InterruptedException e) {
+				}
+			}
+		}
+		return mLooper;
+	}
+
+	/**
+	 * Quits the handler thread's looper.
+	 * <p>
+	 * Causes the handler thread's looper to terminate without processing any
+	 * more messages in the message queue.
+	 * </p><p>
+	 * Any attempt to post messages to the queue after the looper is asked to quit will fail.
+	 * For example, the {@link Handler#sendMessage(Message)} method will return false.
+	 * </p><p class="note">
+	 * Using this method may be unsafe because some messages may not be delivered
+	 * before the looper terminates.  Consider using {@link #quitSafely} instead to ensure
+	 * that all pending work is completed in an orderly manner.
+	 * </p>
+	 *
+	 * @return True if the looper looper has been asked to quit or false if the
+	 * thread had not yet started running.
+	 *
+	 * @see #quitSafely
+	 */
+	public boolean quit() {
+		Looper looper = getLooper();
+		if (looper != null) {
+			looper.quit();
+			return true;
+		}
+		return false;
+	}
+
+	/**
+	 * Quits the handler thread's looper safely.
+	 * <p>
+	 * Causes the handler thread's looper to terminate as soon as all remaining messages
+	 * in the message queue that are already due to be delivered have been handled.
+	 * Pending delayed messages with due times in the future will not be delivered.
+	 * </p><p>
+	 * Any attempt to post messages to the queue after the looper is asked to quit will fail.
+	 * For example, the {@link Handler#sendMessage(Message)} method will return false.
+	 * </p><p>
+	 * If the thread has not been started or has finished (that is if
+	 * {@link #getLooper} returns null), then false is returned.
+	 * Otherwise the looper is asked to quit and true is returned.
+	 * </p>
+	 *
+	 * @return True if the looper looper has been asked to quit or false if the
+	 * thread had not yet started running.
+	 */
+	public boolean quitSafely() {
+		Looper looper = getLooper();
+		if (looper != null) {
+			looper.quitSafely();
+			return true;
+		}
+		return false;
+	}
+
+	/**
+	 * Returns the identifier of this thread. See Process.myTid().
+	 */
+	public int getThreadId() {
+		return mTid;
 	}
 }