OpenTracks/MyTracks/src/com/google/android/apps/mytracks/services/PeriodicTaskExecuter.java

/*
 * Copyright 2009 Google Inc.
 * 
 * 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.google.android.apps.mytracks.services;

import com.google.android.apps.mytracks.MyTracksConstants;

import android.util.Log;

import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

/**
 * This class will periodically announce the user's trip statistics.
 *
 * @author Sandor Dornbush
 */
public class PeriodicTaskExecuter {

  private final PeriodicTask task;
  private final TrackRecordingService service;

  /**
   * A timer to schedule the announcements.
   * This is non-null if the task is in started (scheduled) state.
   */
  private Timer timer;

  public PeriodicTaskExecuter(PeriodicTask task,
                              TrackRecordingService service) {
    this.task = task;
    this.service = service;
  }

  /**
   * Schedules the task at the given interval.
   *
   * @param interval The interval in milliseconds
   */
  public void scheduleTask(long interval) {
    // TODO: Decouple service from this class once and forever.
    if (!service.isRecording()) {
      return;
    }

    if (timer != null) {
      timer.cancel();
      timer.purge();
    } else {
      // First start, or we were previously shut down.
      task.start();
    }

    timer = new Timer();
    if (interval <= 0) {
      return;
    }

    long now = System.currentTimeMillis();
    long next = service.getTripStatistics().getStartTime();
    if (next < now) {
      next = now + interval - ((now - next) % interval);
    }

    Date start = new Date(next);
    Log.i(MyTracksConstants.TAG,
        task.getClass().getSimpleName() + " scheduled to start at " + start
        + " every " + interval + " milliseconds.");
    timer.scheduleAtFixedRate(new PeriodicTimerTask(), start, interval);
  }

  /**
   * Cleans up this object.
   */
  public void shutdown() {
    Log.i(MyTracksConstants.TAG,
        task.getClass().getSimpleName() + " shutting down.");
    if (timer != null) {
      timer.cancel();
      timer.purge();
      timer = null;
      task.shutdown();
    }
  }

  /**
   * The timer task to announce the trip status.
   */
  private class PeriodicTimerTask extends TimerTask {
    @Override
    public void run() {
      task.run(service);
    }
  }
}