content: /*
   * Copyright (C) 2018 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.wm;
  
  import android.annotation.NonNull;
  
  /**
   * Multi-cast delegate implementation for {@link ActivityMetricsLaunchObserver}.
   *
   * <br/><br/>
   * This enables multiple launch observers to subscribe to {@link ActivityMetricsLogger}
   * independently of each other.
   *
   * <br/><br/>
   * Some callbacks in {@link ActivityMetricsLaunchObserver} have a {@code byte[]}
   * parameter; this array is reused by all the registered observers, so it must not be written to
   * (i.e. all observers must treat any array parameters as immutable).
   *
   * <br /><br />
   * Multi-cast invocations occurs sequentially in-order of registered observers.
   */
  public interface ActivityMetricsLaunchObserverRegistry {
      /**
       * Register an extra launch observer to receive the multi-cast.
       *
       * <br /><br />
       * Multi-cast invocation happens in the same order the observers were registered. For example,
       * <pre>
       *     registerLaunchObserver(A)
       *     registerLaunchObserver(B)
       *
       *     obs.onIntentFailed() ->
       *       A.onIntentFailed()
       *       B.onIntentFailed()
       * </pre>
       */
      void registerLaunchObserver(@NonNull ActivityMetricsLaunchObserver launchObserver);
  
      /**
       * Unregister an existing launch observer. It will not receive the multi-cast in the future.
       *
       * <br /><br />
       * This does nothing if this observer was not already registered.
       */
      void unregisterLaunchObserver(@NonNull ActivityMetricsLaunchObserver launchObserver);
  }
  