1 /*
2  * Copyright (C) 2020 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 android.app.compat;
18 
19 import android.annotation.NonNull;
20 import android.app.PropertyInvalidatedCache;
21 import android.content.Context;
22 import android.os.Binder;
23 import android.os.RemoteException;
24 import android.os.ServiceManager;
25 
26 import com.android.internal.compat.IPlatformCompat;
27 
28 /**
29  * Handles caching of calls to {@link com.android.internal.compat.IPlatformCompat}
30  * @hide
31  */
32 public final class ChangeIdStateCache
33         extends PropertyInvalidatedCache<ChangeIdStateQuery, Boolean> {
34     private static final String CACHE_KEY = "cache_key.is_compat_change_enabled";
35     private static final int MAX_ENTRIES = 64;
36     private static boolean sDisabled = false;
37     private volatile IPlatformCompat mPlatformCompat;
38 
39     /** @hide */
ChangeIdStateCache()40     public ChangeIdStateCache() {
41         super(MAX_ENTRIES, CACHE_KEY);
42     }
43 
44     /**
45      * Disable cache.
46      *
47      * <p>Should only be used in unit tests.
48      * @hide
49      */
disable()50     public static void disable() {
51         sDisabled = true;
52     }
53 
54     /**
55      * Invalidate the cache.
56      *
57      * <p>Can only be called by the system server process.
58      * @hide
59      */
invalidate()60     public static void invalidate() {
61         if (!sDisabled) {
62             PropertyInvalidatedCache.invalidateCache(CACHE_KEY);
63         }
64     }
65 
66     @NonNull
getPlatformCompatService()67     IPlatformCompat getPlatformCompatService() {
68         IPlatformCompat platformCompat = mPlatformCompat;
69         if (platformCompat == null) {
70             synchronized (this) {
71                 platformCompat = mPlatformCompat;
72                 if (platformCompat == null) {
73                     platformCompat = IPlatformCompat.Stub.asInterface(
74                         ServiceManager.getService(Context.PLATFORM_COMPAT_SERVICE));
75                     if (platformCompat == null) {
76                         throw new RuntimeException(
77                             "Could not get PlatformCompatService instance!");
78                     }
79                     mPlatformCompat = platformCompat;
80                 }
81             }
82         }
83         return platformCompat;
84     }
85 
86     @Override
recompute(ChangeIdStateQuery query)87     public Boolean recompute(ChangeIdStateQuery query) {
88         final long token = Binder.clearCallingIdentity();
89         try {
90             if (query.type == ChangeIdStateQuery.QUERY_BY_PACKAGE_NAME) {
91                 return getPlatformCompatService().isChangeEnabledByPackageName(query.changeId,
92                                                                    query.packageName,
93                                                                    query.userId);
94             } else if (query.type == ChangeIdStateQuery.QUERY_BY_UID) {
95                 return getPlatformCompatService().isChangeEnabledByUid(query.changeId, query.uid);
96             } else {
97                 throw new IllegalArgumentException("Invalid query type: " + query.type);
98             }
99         } catch (RemoteException e) {
100             e.rethrowFromSystemServer();
101         } finally {
102             Binder.restoreCallingIdentity(token);
103         }
104         throw new IllegalStateException("Could not recompute value!");
105     }
106 }
107