1 /*
2  * Copyright (C) 2010 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.gallery3d.data;
18 
19 import android.content.Context;
20 
21 import com.android.gallery3d.common.BlobCache;
22 import com.android.gallery3d.common.BlobCache.LookupRequest;
23 import com.android.gallery3d.common.Utils;
24 import com.android.gallery3d.data.BytesBufferPool.BytesBuffer;
25 import com.android.gallery3d.util.CacheManager;
26 import com.android.gallery3d.util.GalleryUtils;
27 
28 import java.io.IOException;
29 import java.nio.ByteBuffer;
30 
31 public class ImageCacheService {
32     @SuppressWarnings("unused")
33     private static final String TAG = "ImageCacheService";
34 
35     private static final String IMAGE_CACHE_FILE = "imgcache";
36     private static final int IMAGE_CACHE_MAX_ENTRIES = 5000;
37     private static final int IMAGE_CACHE_MAX_BYTES = 200 * 1024 * 1024;
38     private static final int IMAGE_CACHE_VERSION = 7;
39 
40     private BlobCache mCache;
41 
ImageCacheService(Context context)42     public ImageCacheService(Context context) {
43         mCache = CacheManager.getCache(context, IMAGE_CACHE_FILE,
44                 IMAGE_CACHE_MAX_ENTRIES, IMAGE_CACHE_MAX_BYTES,
45                 IMAGE_CACHE_VERSION);
46     }
47 
48     /**
49      * Gets the cached image data for the given <code>path</code>,
50      *  <code>timeModified</code> and <code>type</code>.
51      *
52      * The image data will be stored in <code>buffer.data</code>, started from
53      * <code>buffer.offset</code> for <code>buffer.length</code> bytes. If the
54      * buffer.data is not big enough, a new byte array will be allocated and returned.
55      *
56      * @return true if the image data is found; false if not found.
57      */
getImageData(Path path, long timeModified, int type, BytesBuffer buffer)58     public boolean getImageData(Path path, long timeModified, int type, BytesBuffer buffer) {
59         byte[] key = makeKey(path, timeModified, type);
60         long cacheKey = Utils.crc64Long(key);
61         try {
62             LookupRequest request = new LookupRequest();
63             request.key = cacheKey;
64             request.buffer = buffer.data;
65             synchronized (mCache) {
66                 if (!mCache.lookup(request)) return false;
67             }
68             if (isSameKey(key, request.buffer)) {
69                 buffer.data = request.buffer;
70                 buffer.offset = key.length;
71                 buffer.length = request.length - buffer.offset;
72                 return true;
73             }
74         } catch (IOException ex) {
75             // ignore.
76         }
77         return false;
78     }
79 
putImageData(Path path, long timeModified, int type, byte[] value)80     public void putImageData(Path path, long timeModified, int type, byte[] value) {
81         byte[] key = makeKey(path, timeModified, type);
82         long cacheKey = Utils.crc64Long(key);
83         ByteBuffer buffer = ByteBuffer.allocate(key.length + value.length);
84         buffer.put(key);
85         buffer.put(value);
86         synchronized (mCache) {
87             try {
88                 mCache.insert(cacheKey, buffer.array());
89             } catch (IOException ex) {
90                 // ignore.
91             }
92         }
93     }
94 
clearImageData(Path path, long timeModified, int type)95     public void clearImageData(Path path, long timeModified, int type) {
96         byte[] key = makeKey(path, timeModified, type);
97         long cacheKey = Utils.crc64Long(key);
98         synchronized (mCache) {
99             try {
100                 mCache.clearEntry(cacheKey);
101             } catch (IOException ex) {
102                 // ignore.
103             }
104         }
105     }
106 
makeKey(Path path, long timeModified, int type)107     private static byte[] makeKey(Path path, long timeModified, int type) {
108         return GalleryUtils.getBytes(path.toString() + "+" + timeModified + "+" + type);
109     }
110 
isSameKey(byte[] key, byte[] buffer)111     private static boolean isSameKey(byte[] key, byte[] buffer) {
112         int n = key.length;
113         if (buffer.length < n) {
114             return false;
115         }
116         for (int i = 0; i < n; ++i) {
117             if (key[i] != buffer[i]) {
118                 return false;
119             }
120         }
121         return true;
122     }
123 }
124