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 
ImageDecorator(ImageProxy proxy)42         public ImageDecorator(ImageProxy proxy) {
43             super(proxy);
44             mClosed = new AtomicBoolean(false);
45         }
46 
47         @Override
close()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 
CloseWhenDoneImageReader(ImageReaderProxy delegate)64     public CloseWhenDoneImageReader(ImageReaderProxy delegate) {
65         super(delegate);
66         mLock = new Object();
67         mClosed = false;
68         mOpenImages = 0;
69     }
70 
decrementImageCount()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
acquireNextImage()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
acquireLatestImage()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
close()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