scheduler.js

// Copyright 2012 and onwards 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.

/**
 * @fileoverview Performs operations that must be done on a schedule: e.g.
 * updating the badge, fetching new events from the server, etc.
 *
 * @author manas@google.com (Manas Tungare)
 */

/**
 * The namespace for all scheduling operations.
 */
var scheduler = {};

/**
 * Poll the server every 6 hours for new calendars that may have been added.
 * @type {number}
 * @const
 * @private
 */
scheduler.CALENDARS_POLL_INTERVAL_MS_ = 6 * 60 * 60 * 1000;

/**
 * Poll the server every hour for new calendar events, but not new calendars.
 * @type {number}
 * @const
 * @private
 */
scheduler.EVENTS_POLL_INTERVAL_MS_ = 60 * 60 * 1000;

/**
 * Update the badge every minute.
 * @type {number}
 * @const
 * @private
 */
scheduler.BADGE_UPDATE_INTERVAL_MS_ = 60 * 1000;

/**
 * Starts the scheduler that updates the badge (more often) and the feed from
 * the calendar (less often).
 */
scheduler.start = function() {
  background.log('scheduler.start()');

  // Do a one-time initial fetch on load. Settings are only refreshed when restarting Chrome.
  feeds.fetchSettings();
  feeds.fetchCalendars();

  window.setInterval(function() {
    feeds.refreshUI();

    var now = (new Date()).getTime();
    if (!feeds.lastFetchedAt) {
      // If never successfully fetched before, fetch the list of calendars now.
      feeds.fetchSettings();
      feeds.fetchCalendars();
    } else {
      var feedsFetchedAtMs = feeds.lastFetchedAt.getTime();
      if (now - feedsFetchedAtMs > scheduler.CALENDARS_POLL_INTERVAL_MS_) {
        feeds.fetchCalendars();  // Will trigger fetchEvents automatically.
      } else if (now - feedsFetchedAtMs > scheduler.EVENTS_POLL_INTERVAL_MS_) {
        feeds.fetchEvents();
      }
    }
  }, scheduler.BADGE_UPDATE_INTERVAL_MS_);
};