Add LocalManagerRegistry inside system server.

This is similar to LocalServices, but dedicated to module API in the
same process.

Bug: 158736025
Test: presubmit
Change-Id: Ib9f14070a665ebd8c582376d7ea044d9b945b6b0

services/api/current.txt

@@ -46,6 +46,11 @@ package com.android.role.persistence {
 
 package com.android.server {
 
+  public final class LocalManagerRegistry {
+    method public static <T> void addManager(@NonNull Class<T>, @NonNull T);
+    method @Nullable public static <T> T getManager(@NonNull Class<T>);
+  }
+
   public abstract class SystemService {
     ctor public SystemService(@NonNull android.content.Context);
     method @NonNull public final android.content.Context getContext();

services/core/java/com/android/server/LocalManagerRegistry.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.util.ArrayMap;
+
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * The registry for in-process module interfaces.
+ * <p>
+ * In-process module interfaces should be named with the suffix {@code ManagerLocal} for
+ * consistency.
+ *
+ * @hide
+ */
+@SystemApi(client = SystemApi.Client.SYSTEM_SERVER)
+public final class LocalManagerRegistry {
+    private LocalManagerRegistry() {}
+
+    @NonNull
+    private static final Map<Class<?>, Object> sManagers = new ArrayMap<>();
+
+    /**
+     * Get a manager from the registry.
+     *
+     * @param managerClass the class that the manager implements
+     * @return the manager, or {@code null} if not found
+     */
+    @Nullable
+    @SuppressWarnings("unchecked")
+    public static <T> T getManager(@NonNull Class<T> managerClass) {
+        synchronized (sManagers) {
+            return (T) sManagers.get(managerClass);
+        }
+    }
+
+    /**
+     * Adds a manager to the registry.
+     *
+     * @param managerClass the class that the manager implements
+     * @param manager the manager
+     * @throws IllegalStateException if the manager class is already registered
+     */
+    public static <T> void addManager(@NonNull Class<T> managerClass, @NonNull T manager) {
+        Objects.requireNonNull(managerClass, "managerClass");
+        Objects.requireNonNull(manager, "manager");
+        synchronized (sManagers) {
+            if (sManagers.containsKey(managerClass)) {
+                throw new IllegalStateException(managerClass.getName() + " is already registered");
+            }
+            sManagers.put(managerClass, manager);
+        }
+    }
+}