content: /*
   * Copyright (C) 2015 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.internal.util;
  
  import android.app.AlarmManager;
  import android.content.Context;
  import android.os.Handler;
  import android.os.Message;
  
  import com.android.internal.annotations.VisibleForTesting;
  
   /**
   * An AlarmListener that sends the specified message to a Handler and keeps the system awake until
   * the message is processed.
   *
   * This is useful when using the AlarmManager direct callback interface to wake up the system and
   * request that an object whose API consists of messages (such as a StateMachine) perform some
   * action.
   *
   * In this situation, using AlarmManager.onAlarmListener by itself will wake up the system to send
   * the message, but does not guarantee that the system will be awake until the target object has
   * processed it. This is because as soon as the onAlarmListener sends the message and returns, the
   * AlarmManager releases its wakelock and the system is free to go to sleep again.
   */
  public class WakeupMessage implements AlarmManager.OnAlarmListener {
      private final AlarmManager mAlarmManager;
  
      @VisibleForTesting
      protected final Handler mHandler;
      @VisibleForTesting
      protected final String mCmdName;
      @VisibleForTesting
      protected final int mCmd, mArg1, mArg2;
      @VisibleForTesting
      protected final Object mObj;
      private final Runnable mRunnable;
      private boolean mScheduled;
  
      public WakeupMessage(Context context, Handler handler,
              String cmdName, int cmd, int arg1, int arg2, Object obj) {
          mAlarmManager = getAlarmManager(context);
          mHandler = handler;
          mCmdName = cmdName;
          mCmd = cmd;
          mArg1 = arg1;
          mArg2 = arg2;
          mObj = obj;
          mRunnable = null;
      }
  
      public WakeupMessage(Context context, Handler handler, String cmdName, int cmd, int arg1) {
          this(context, handler, cmdName, cmd, arg1, 0, null);
      }
  
      public WakeupMessage(Context context, Handler handler,
              String cmdName, int cmd, int arg1, int arg2) {
          this(context, handler, cmdName, cmd, arg1, arg2, null);
      }
  
      public WakeupMessage(Context context, Handler handler, String cmdName, int cmd) {
          this(context, handler, cmdName, cmd, 0, 0, null);
      }
  
      public WakeupMessage(Context context, Handler handler, String cmdName, Runnable runnable) {
          mAlarmManager = getAlarmManager(context);
          mHandler = handler;
          mCmdName = cmdName;
          mCmd = 0;
          mArg1 = 0;
          mArg2 = 0;
          mObj = null;
          mRunnable = runnable;
      }
  
      private static AlarmManager getAlarmManager(Context context) {
          return (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
      }
  
      /**
       * Schedule the message to be delivered at the time in milliseconds of the
       * {@link android.os.SystemClock#elapsedRealtime SystemClock.elapsedRealtime()} clock and wakeup
       * the device when it goes off. If schedule is called multiple times without the message being
       * dispatched then the alarm is rescheduled to the new time.
       */
      public synchronized void schedule(long when) {
          mAlarmManager.setExact(
                  AlarmManager.ELAPSED_REALTIME_WAKEUP, when, mCmdName, this, mHandler);
          mScheduled = true;
      }
  
      /**
       * Cancel all pending messages. This includes alarms that may have been fired, but have not been
       * run on the handler yet.
       */
      public synchronized void cancel() {
          if (mScheduled) {
              mAlarmManager.cancel(this);
              mScheduled = false;
          }
      }
  
      @Override
      public void onAlarm() {
          // Once this method is called the alarm has already been fired and removed from
          // AlarmManager (it is still partially tracked, but only for statistics). The alarm can now
          // be marked as unscheduled so that it can be rescheduled in the message handler.
          final boolean stillScheduled;
          synchronized (this) {
              stillScheduled = mScheduled;
              mScheduled = false;
          }
          if (stillScheduled) {
              Message msg;
              if (mRunnable == null) {
                  msg = mHandler.obtainMessage(mCmd, mArg1, mArg2, mObj);
              } else {
                  msg = Message.obtain(mHandler, mRunnable);
              }
              mHandler.dispatchMessage(msg);
              msg.recycle();
          }
      }
  }
  