openproject/frontend/app/services/cache-service.js

//-- copyright
// OpenProject is a project management system.
// Copyright (C) 2012-2015 the OpenProject Foundation (OPF)
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License version 3.
//
// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
// Copyright (C) 2006-2013 Jean-Philippe Lang
// Copyright (C) 2010-2013 the ChiliProject Team
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// See doc/COPYRIGHT.rdoc for more details.
//++

module.exports = function (HALAPIResource,
                           $http,
                           $q,
                           $window,
                           CacheFactory) {

  var cacheName = 'openproject-cache',
    _promises = {},
    _cache = CacheFactory.get(cacheName);

  if (!_cache) {
    _cache = CacheFactory(cacheName, {
      maxAge: 10 * 60 * 1000, // 10 mins
      storageMode: 'sessionStorage',
    });
  }

  var CacheService = {

    cache: function (key, value) {
      _cache.put(key, value);
    },

    get: function (key) {
      return _cache.get(key);
    },

    remove: function (key) {
      _cache.remove(key);
    },

    loadResource: function (resource, force) {
      var key = resource.props.href,
        cacheDisabled = $window.openProject.environment === 'test',
        cached,
        _fetchResource = function () {
          var deferred = $q.defer();

          resource.fetch().then(function (data) {
            CacheService.cache(key, data);
            deferred.resolve(data);
          }, function () {
            deferred.reject();
            CacheService.remove(key);
          });

          return deferred.promise;
        };

      // Return early when frontend caching is not desired
      if (cacheDisabled) {
        return _fetchResource();
      }

      // Got the result directly? Great.
      cached = CacheService.get(key);
      if (cached && !force) {
        var deferred = $q.defer();
        deferred.resolve(cached);
        return deferred.promise;
      }

      // Return an existing promise if it exists
      // Avoids intermittent requests while a first
      // is already underway.
      if (_promises[key]) {
        return _promises[key];
      }

      var promise = _fetchResource();
      _promises[key] = promise;
      return promise;
    }
  };

  return CacheService;
};