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 com.android.server;
18 
19 import android.annotation.NonNull;
20 import android.annotation.Nullable;
21 import android.annotation.SystemApi;
22 import android.util.ArrayMap;
23 
24 import java.util.Map;
25 import java.util.Objects;
26 
27 /**
28  * The registry for in-process module interfaces.
29  * <p>
30  * In-process module interfaces should be named with the suffix {@code ManagerLocal} for
31  * consistency.
32  *
33  * @hide
34  */
35 @SystemApi(client = SystemApi.Client.SYSTEM_SERVER)
36 public final class LocalManagerRegistry {
LocalManagerRegistry()37     private LocalManagerRegistry() {}
38 
39     @NonNull
40     private static final Map<Class<?>, Object> sManagers = new ArrayMap<>();
41 
42     /**
43      * Get a manager from the registry.
44      *
45      * @param managerClass the class that the manager implements
46      * @return the manager, or {@code null} if not found
47      */
48     @Nullable
49     @SuppressWarnings("unchecked")
getManager(@onNull Class<T> managerClass)50     public static <T> T getManager(@NonNull Class<T> managerClass) {
51         synchronized (sManagers) {
52             return (T) sManagers.get(managerClass);
53         }
54     }
55 
56     /**
57      * Returns a manager from the registry, or throws {@link ManagerNotFoundException} if not found.
58      *
59      * @hide
60      */
61     @NonNull
getManagerOrThrow(@onNull Class<T> managerClass)62     public static <T> T getManagerOrThrow(@NonNull Class<T> managerClass)
63             throws ManagerNotFoundException {
64         T manager = getManager(managerClass);
65         if (manager == null) {
66             throw new ManagerNotFoundException(managerClass);
67         }
68         return manager;
69     }
70 
71     /**
72      * Adds a manager to the registry.
73      *
74      * @param managerClass the class that the manager implements
75      * @param manager the manager
76      * @throws IllegalStateException if the manager class is already registered
77      */
addManager(@onNull Class<T> managerClass, @NonNull T manager)78     public static <T> void addManager(@NonNull Class<T> managerClass, @NonNull T manager) {
79         Objects.requireNonNull(managerClass, "managerClass");
80         Objects.requireNonNull(manager, "manager");
81         synchronized (sManagers) {
82             if (sManagers.containsKey(managerClass)) {
83                 throw new IllegalStateException(managerClass.getName() + " is already registered");
84             }
85             sManagers.put(managerClass, manager);
86         }
87     }
88 
89     /**
90      * Exception thrown when no local manager published for given class.
91      *
92      * @hide
93      */
94     public static class ManagerNotFoundException extends Exception {
ManagerNotFoundException(@onNull Class<T> managerClass)95         public <T> ManagerNotFoundException(@NonNull Class<T> managerClass) {
96             super("Local manager " + managerClass.getName() + " does not exist or is not ready");
97         }
98     }
99 }
100