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
17package com.android.gallery3d.util;
18
19import com.android.gallery3d.common.BlobCache;
20
21import android.content.Context;
22import android.content.SharedPreferences;
23import android.preference.PreferenceManager;
24
25import java.io.File;
26import java.io.IOException;
27import java.util.HashMap;
28
29public class CacheManager {
30    private static final String TAG = "CacheManager";
31    private static final String KEY_CACHE_UP_TO_DATE = "cache-up-to-date";
32    private static HashMap<String, BlobCache> sCacheMap =
33            new HashMap<String, BlobCache>();
34    private static boolean sOldCheckDone = false;
35
36    // Return null when we cannot instantiate a BlobCache, e.g.:
37    // there is no SD card found.
38    // This can only be called from data thread.
39    public static BlobCache getCache(Context context, String filename,
40            int maxEntries, int maxBytes, int version) {
41        synchronized (sCacheMap) {
42            if (!sOldCheckDone) {
43                removeOldFilesIfNecessary(context);
44                sOldCheckDone = true;
45            }
46            BlobCache cache = sCacheMap.get(filename);
47            if (cache == null) {
48                File cacheDir = context.getExternalCacheDir();
49                String path = cacheDir.getAbsolutePath() + "/" + filename;
50                try {
51                    cache = new BlobCache(path, maxEntries, maxBytes, false,
52                            version);
53                    sCacheMap.put(filename, cache);
54                } catch (IOException e) {
55                    Log.e(TAG, "Cannot instantiate cache!", e);
56                }
57            }
58            return cache;
59        }
60    }
61
62    // Removes the old files if the data is wiped.
63    private static void removeOldFilesIfNecessary(Context context) {
64        SharedPreferences pref = PreferenceManager
65                .getDefaultSharedPreferences(context);
66        int n = 0;
67        try {
68            n = pref.getInt(KEY_CACHE_UP_TO_DATE, 0);
69        } catch (Throwable t) {
70            // ignore.
71        }
72        if (n != 0) return;
73        pref.edit().putInt(KEY_CACHE_UP_TO_DATE, 1).commit();
74
75        File cacheDir = context.getExternalCacheDir();
76        String prefix = cacheDir.getAbsolutePath() + "/";
77
78        BlobCache.deleteFiles(prefix + "imgcache");
79        BlobCache.deleteFiles(prefix + "rev_geocoding");
80        BlobCache.deleteFiles(prefix + "bookmark");
81    }
82}
83