content: /*
   * Copyright (C) 2017 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;
  import android.app.IApplicationThread;
  import android.app.servertransaction.ClientTransaction;
  import android.app.servertransaction.ClientTransactionItem;
  import android.app.servertransaction.ActivityLifecycleItem;
  import android.os.Binder;
  import android.os.IBinder;
  import android.os.RemoteException;
  
  /**
   * Class that is able to combine multiple client lifecycle transition requests and/or callbacks,
   * and execute them as a single transaction.
   *
   * @see ClientTransaction
   */
  class ClientLifecycleManager {
      // TODO(lifecycler): Implement building transactions or global transaction.
      // TODO(lifecycler): Use object pools for transactions and transaction items.
  
      /**
       * Schedule a transaction, which may consist of multiple callbacks and a lifecycle request.
       * @param transaction A sequence of client transaction items.
       * @throws RemoteException
       *
       * @see ClientTransaction
       */
      void scheduleTransaction(ClientTransaction transaction) throws RemoteException {
          final IApplicationThread client = transaction.getClient();
          transaction.schedule();
          if (!(client instanceof Binder)) {
              // If client is not an instance of Binder - it's a remote call and at this point it is
              // safe to recycle the object. All objects used for local calls will be recycled after
              // the transaction is executed on client in ActivityThread.
              transaction.recycle();
          }
      }
  
      /**
       * Schedule a single lifecycle request or callback to client activity.
       * @param client Target client.
       * @param activityToken Target activity token.
       * @param stateRequest A request to move target activity to a desired lifecycle state.
       * @throws RemoteException
       *
       * @see ClientTransactionItem
       */
      void scheduleTransaction(@NonNull IApplicationThread client, @NonNull IBinder activityToken,
              @NonNull ActivityLifecycleItem stateRequest) throws RemoteException {
          final ClientTransaction clientTransaction = transactionWithState(client, activityToken,
                  stateRequest);
          scheduleTransaction(clientTransaction);
      }
  
      /**
       * Schedule a single callback delivery to client activity.
       * @param client Target client.
       * @param activityToken Target activity token.
       * @param callback A request to deliver a callback.
       * @throws RemoteException
       *
       * @see ClientTransactionItem
       */
      void scheduleTransaction(@NonNull IApplicationThread client, @NonNull IBinder activityToken,
              @NonNull ClientTransactionItem callback) throws RemoteException {
          final ClientTransaction clientTransaction = transactionWithCallback(client, activityToken,
                  callback);
          scheduleTransaction(clientTransaction);
      }
  
      /**
       * Schedule a single callback delivery to client application.
       * @param client Target client.
       * @param callback A request to deliver a callback.
       * @throws RemoteException
       *
       * @see ClientTransactionItem
       */
      void scheduleTransaction(@NonNull IApplicationThread client,
              @NonNull ClientTransactionItem callback) throws RemoteException {
          final ClientTransaction clientTransaction = transactionWithCallback(client,
                  null /* activityToken */, callback);
          scheduleTransaction(clientTransaction);
      }
  
      /**
       * @return A new instance of {@link ClientTransaction} with a single lifecycle state request.
       *
       * @see ClientTransaction
       * @see ClientTransactionItem
       */
      private static ClientTransaction transactionWithState(@NonNull IApplicationThread client,
              @NonNull IBinder activityToken, @NonNull ActivityLifecycleItem stateRequest) {
          final ClientTransaction clientTransaction = ClientTransaction.obtain(client, activityToken);
          clientTransaction.setLifecycleStateRequest(stateRequest);
          return clientTransaction;
      }
  
      /**
       * @return A new instance of {@link ClientTransaction} with a single callback invocation.
       *
       * @see ClientTransaction
       * @see ClientTransactionItem
       */
      private static ClientTransaction transactionWithCallback(@NonNull IApplicationThread client,
              IBinder activityToken, @NonNull ClientTransactionItem callback) {
          final ClientTransaction clientTransaction = ClientTransaction.obtain(client, activityToken);
          clientTransaction.addCallback(callback);
          return clientTransaction;
      }
  }
  