| /* |
| * Copyright (C) 2010 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.util; |
| |
| import java.lang.ref.PhantomReference; |
| import java.lang.ref.Reference; |
| import java.lang.ref.ReferenceQueue; |
| |
| /** |
| * This class can be used to implement reliable finalizers. |
| * |
| * @hide |
| */ |
| public final class Finalizers { |
| private static final String LOG_TAG = "Finalizers"; |
| |
| private static final Object[] sLock = new Object[0]; |
| private static boolean sInit; |
| private static Reclaimer sReclaimer; |
| |
| /** |
| * Subclass of PhantomReference used to reclaim resources. |
| */ |
| public static abstract class ReclaimableReference<T> extends PhantomReference<T> { |
| public ReclaimableReference(T r, ReferenceQueue<Object> q) { |
| super(r, q); |
| } |
| |
| public abstract void reclaim(); |
| } |
| |
| /** |
| * Returns the queue used to reclaim ReclaimableReferences. |
| * |
| * @return A reference queue or null before initialization |
| */ |
| public static ReferenceQueue<Object> getQueue() { |
| synchronized (sLock) { |
| if (!sInit) { |
| return null; |
| } |
| if (!sReclaimer.isRunning()) { |
| sReclaimer = new Reclaimer(sReclaimer.mQueue); |
| sReclaimer.start(); |
| } |
| return sReclaimer.mQueue; |
| } |
| } |
| |
| /** |
| * Invoked by Zygote. Don't touch! |
| */ |
| public static void init() { |
| synchronized (sLock) { |
| if (!sInit && sReclaimer == null) { |
| sReclaimer = new Reclaimer(); |
| sReclaimer.start(); |
| sInit = true; |
| } |
| } |
| } |
| |
| private static class Reclaimer extends Thread { |
| ReferenceQueue<Object> mQueue; |
| |
| private volatile boolean mRunning = false; |
| |
| Reclaimer() { |
| this(new ReferenceQueue<Object>()); |
| } |
| |
| Reclaimer(ReferenceQueue<Object> queue) { |
| super("Reclaimer"); |
| setDaemon(true); |
| mQueue = queue; |
| } |
| |
| @Override |
| public void start() { |
| mRunning = true; |
| super.start(); |
| } |
| |
| boolean isRunning() { |
| return mRunning; |
| } |
| |
| @SuppressWarnings({"InfiniteLoopStatement"}) |
| @Override |
| public void run() { |
| try { |
| while (true) { |
| try { |
| cleanUp(mQueue.remove()); |
| } catch (InterruptedException e) { |
| // Ignore |
| } |
| } |
| } catch (Exception e) { |
| Log.e(LOG_TAG, "Reclaimer thread exiting: ", e); |
| } finally { |
| mRunning = false; |
| } |
| } |
| |
| private void cleanUp(Reference<?> reference) { |
| do { |
| reference.clear(); |
| ((ReclaimableReference<?>) reference).reclaim(); |
| } while ((reference = mQueue.poll()) != null); |
| } |
| } |
| } |