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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.camera.one.v2;
     18 
     19 import com.android.camera.one.v2.camera2proxy.ForwardingImageProxy;
     20 import com.android.camera.one.v2.camera2proxy.ForwardingImageReader;
     21 import com.android.camera.one.v2.camera2proxy.ImageProxy;
     22 import com.android.camera.one.v2.camera2proxy.ImageReaderProxy;
     23 
     24 import java.util.concurrent.atomic.AtomicBoolean;
     25 
     26 import javax.annotation.Nullable;
     27 import javax.annotation.concurrent.GuardedBy;
     28 import javax.annotation.concurrent.ThreadSafe;
     29 
     30 /**
     31  * Defers closing the underlying {@link ImageReaderProxy} until all images have
     32  * been released.
     33  * <p>
     34  * TODO Rename to something nicer
     35  */
     36 @ThreadSafe
     37 public final class CloseWhenDoneImageReader extends ForwardingImageReader implements
     38         ImageReaderProxy {
     39     private class ImageDecorator extends ForwardingImageProxy {
     40         private final AtomicBoolean mClosed;
     41 
     42         public ImageDecorator(ImageProxy proxy) {
     43             super(proxy);
     44             mClosed = new AtomicBoolean(false);
     45         }
     46 
     47         @Override
     48         public void close() {
     49             if (!mClosed.getAndSet(true)) {
     50                 super.close();
     51                 decrementImageCount();
     52             }
     53         }
     54     }
     55 
     56     private final Object mLock;
     57     @GuardedBy("mLock")
     58     private boolean mClosePending;
     59     @GuardedBy("mLock")
     60     private boolean mClosed;
     61     @GuardedBy("mLock")
     62     private int mOpenImages;
     63 
     64     public CloseWhenDoneImageReader(ImageReaderProxy delegate) {
     65         super(delegate);
     66         mLock = new Object();
     67         mClosed = false;
     68         mOpenImages = 0;
     69     }
     70 
     71     private void decrementImageCount() {
     72         synchronized (mLock) {
     73             mOpenImages--;
     74             if (mClosePending && !mClosed && mOpenImages == 0) {
     75                 mClosed = true;
     76                 super.close();
     77             }
     78         }
     79     }
     80 
     81     @Override
     82     @Nullable
     83     public ImageProxy acquireNextImage() {
     84         synchronized (mLock) {
     85             if (!mClosePending && !mClosed) {
     86                 ImageProxy image = super.acquireNextImage();
     87                 if (image != null) {
     88                     mOpenImages++;
     89                     return new ImageDecorator(image);
     90                 }
     91             }
     92         }
     93         return null;
     94     }
     95 
     96     @Override
     97     @Nullable
     98     public ImageProxy acquireLatestImage() {
     99         synchronized (mLock) {
    100             if (!mClosePending && !mClosed) {
    101                 ImageProxy image = super.acquireLatestImage();
    102                 if (image != null) {
    103                     mOpenImages++;
    104                     return new ImageDecorator(image);
    105                 }
    106             }
    107         }
    108         return null;
    109     }
    110 
    111     @Override
    112     public void close() {
    113         synchronized (mLock) {
    114             if (mClosed || mClosePending) {
    115                 return;
    116             }
    117             mClosePending = true;
    118             if (mOpenImages == 0) {
    119                 mClosed = true;
    120                 super.close();
    121             }
    122         }
    123     }
    124 }
    125