Prevent polling requests from being queued up

lib/assets/javascripts/cartodb/common/background_polling/models/geocoding_model.js

@@ -1,12 +1,11 @@
 var Backbone = require('backbone');
 var _ = require('underscore');
-var pollTimer = 2000;
+var GeocodingModelPoller = require('./geocoding_model_poller');
 
 /**
  *  Geocoding model
  *
  */
-
 module.exports = cdb.core.Model.extend({
 
   options: {
@@ -35,16 +34,17 @@ module.exports = cdb.core.Model.extend({
   },
 
   initialize: function(opts) {
+    var self = this;
     this._initBinds();
     _.extend(this.options, opts);
+    this.poller = new GeocodingModelPoller(this);
     if (this.options.startPollingAutomatically) {
-      this._checkModel();  
-    }
+      this._checkModel();
+    };
   },
 
   _initBinds: function() {
     this.bind('change:id', this._checkModel, this);
-    this.bind('change:state', this._checkState, this);
   },
 
   _checkModel: function() {
@@ -74,33 +74,12 @@ module.exports = cdb.core.Model.extend({
     }
   },
 
-  // checks for poll to finish
-  pollCheck: function(i) {
-    var self = this;
-
-    if (this.pollTimer) {
-      return false;
-    }
-
-    this.pollTimer = setInterval(function() {
-      self.fetch({
-        error: function(e) {
-          self.trigger("change");
-        }
-      });
-    }, pollTimer);
+  pollCheck: function() {
+    this.poller.start();
   },
 
   destroyCheck: function() {
-    clearInterval(this.pollTimer);
-    delete this.pollTimer;
-  },
-
-  _checkState: function() {
-    var state = this.get('state');
-    if (this.hasFailed() || this.hasCompleted()) {
-      this.destroyCheck();
-    }
+    this.poller.stop();
   },
 
   getError: function() {
@@ -121,13 +100,10 @@ module.exports = cdb.core.Model.extend({
   },
 
   cancelGeocoding: function() {
-    this.destroyCheck();
     this.save({ state: 'cancelled' }, { wait:true });
   },
 
   resetGeocoding: function() {
-    this.destroyCheck();
     this.set('state', 'reset');
   }
-
 });

lib/assets/javascripts/cartodb/common/background_polling/models/geocoding_model_poller.js

@@ -0,0 +1,22 @@
+var Poller = require('./poller');
+
+var GeocodingModelPoller = function(model) {
+
+  var POLLING_INTERVAL = 2000;
+
+  var options = {
+    interval: POLLING_INTERVAL,
+    stopWhen: function(model) {
+      return model.hasFailed() || model.hasCompleted();
+    },
+    error: function(model) {
+      model.trigger("change");
+    }
+  };
+
+  Poller.call(this, model, options);
+};
+
+GeocodingModelPoller.prototype = _.extend({}, Poller.prototype);
+
+module.exports = GeocodingModelPoller;

lib/assets/javascripts/cartodb/common/background_polling/models/import_model.js

@@ -1,15 +1,12 @@
 var cdb = require('cartodb.js');
 var cdbAdmin = require('cdb.admin');
-var pollTimer = 2000; // Interval time between poll checkings
-var timerMultiply = 2.5;  // Multiply interval for this number
-var maxTries = 30; // Max tries until interval change
+var ImportModelPoller = require('./import_model_poller');
 
 /**
  *  New import model that controls
  *  the state of an import
  *
  */
-
 module.exports = cdb.core.Model.extend({
 
   url: function(method) {
@@ -25,11 +22,10 @@ module.exports = cdb.core.Model.extend({
 
   initialize: function() {
     this._initBinds();
+    this.poller = new ImportModelPoller(this);
   },
 
   _initBinds: function() {
-    this.bind('change:state', this._checkState, this);
-    this.bind('change:success', this._checkState, this);
     this.bind('change:item_queue_id', this._checkQueueId, this);
   },
 
@@ -39,13 +35,6 @@ module.exports = cdb.core.Model.extend({
     this[ data.interval > 0 ? '_createSyncImport' : '_createRegularImport'](d);
   },
 
-  _checkState: function() {
-    var state = this.get('state');
-    if (state === "complete" || state === "failure") {
-      this.destroyCheck();
-    }
-  },
-
   _checkQueueId: function() {
     if (this.get('item_queue_id')) {
       this.pollCheck();
@@ -138,28 +127,11 @@ module.exports = cdb.core.Model.extend({
   },
 
   pollCheck: function() {
-    if (this.pollTimer) return;
-    var self = this;
-    var tries = 0;
-    this.pollTimer = setInterval(request, pollTimer);
-
-    function request() {
-      self.destroyCheck();
-      self.fetch();
-      ++tries;
-      // Multiply polling timer by a number when a max
-      // of tries have been reached
-      var multiply = tries > maxTries ? timerMultiply : 1 ;
-      self.pollTimer = setInterval(request, pollTimer * multiply);
-    }
-
-    // Start doing a fetch
-    self.fetch();
+    this.poller.start();
   },
 
   destroyCheck: function() {
-    clearInterval(this.pollTimer);
-    delete this.pollTimer;
+    this.poller.stop();
   }
 
 });

lib/assets/javascripts/cartodb/common/background_polling/models/import_model_poller.js

@@ -0,0 +1,27 @@
+var Poller = require('./poller');
+
+var ImportModelPoller = function(model) {
+
+  var POLLING_INTERVAL = 2000; // Interval time between poll checkings
+  var POLLING_INTERVAL_MULTIPLIER = 2.5;  // Multiply interval by this number
+  var POLLING_REQUESTS_BEFORE_INTERVAL_CHANGE = 30; // Max tries until interval change
+
+  var options = {
+    interval: function(numberOfRequests) {
+      if (numberOfRequests >= POLLING_REQUESTS_BEFORE_INTERVAL_CHANGE) {
+        return POLLING_INTERVAL * POLLING_INTERVAL_MULTIPLIER;
+      }
+      return POLLING_INTERVAL;
+    },
+    stopWhen: function(model) {
+      var state = model.get('state');
+      return (state === "complete" || state === "failure");
+    }
+  };
+
+  Poller.call(this, model, options);
+};
+
+ImportModelPoller.prototype = _.extend({}, Poller.prototype);
+
+module.exports = ImportModelPoller;

lib/assets/javascripts/cartodb/common/background_polling/models/poller.js

@@ -0,0 +1,81 @@
+/*
+ * Periodically fetches a model/collection. It waits for ongoing 
+ * fetch requests before trying to fetch again. A stop condition
+ * can be specified.
+ *
+ * Usage example:
+ * 
+ * var poller = new Poller(model, {
+ *   interval: 1000,
+ *   stopWhen: function(model) {
+ *     return model.get('state') === 'completed';
+ *   }
+ * });
+ * 
+ * poller.start();
+ *
+ * // ...
+ *
+ * poller.stop();
+ * 
+ */
+var Poller = function(model, options) {
+  this.model = model;
+  this.numberOfRequests = 0;
+  this.polling = false;
+  this.interval = options['interval'];
+  if (typeof this.interval !== "function") {
+    this.interval = function() { return options['interval']; };
+  }
+  this.stopWhen = options['stopWhen'];
+  this.error = options['error'];
+  this.autoStart = options['autoStart'];
+
+  if (this.autoStart) {
+    this.start();
+  }
+}
+
+Poller.prototype.start = function() {
+  if (this.timeout) {
+    return;
+  }
+
+  this._scheduleFetch();
+}
+
+Poller.prototype._scheduleFetch = function() {
+  this.timeout = setTimeout(this._fetch.bind(this), this.interval(this.numberOfRequests));
+}
+
+Poller.prototype._fetch = function() {
+  var self = this;
+  if (!self.polling) {
+    self.polling = true;
+    self.model.fetch({
+      success: function() {
+        self.polling = false;
+        self.numberOfRequests++;
+        if (self._continuePolling()) {
+          self._scheduleFetch();
+        }
+      },
+      error: function(e) {
+        _.isFunction(self.error) && self.error(self.model);
+      }
+    })
+  }
+}
+
+Poller.prototype._continuePolling = function() {
+  return !this.stopWhen ||
+    (_.isFunction(this.stopWhen) && !this.stopWhen(this.model));
+}
+
+Poller.prototype.stop = function() {
+  this.polling = false;
+  clearTimeout(this.timeout);
+  delete(this.timeout);
+}
+
+module.exports = Poller;

lib/assets/test/spec/cartodb/common/background_importer/geocoding_model.spec.js

@@ -28,35 +28,46 @@ describe('common/background_polling/geocoding_model', function() {
   it('should have several change binds', function() {
     this.model._initBinds();
     expect(this.model.bind.calls.argsFor(0)[0]).toEqual('change:id');
-    expect(this.model.bind.calls.argsFor(1)[0]).toEqual('change:state');
   });
 
-  describe('polling', function() {
+  describe('.pollCheck', function() {
 
     beforeEach(function() {
-      this.model.set('id', '1');
-      spyOn(this.model, 'fetch').and.callThrough();
+      jasmine.clock().install();
+      spyOn(this.model, 'fetch');
+    });
+
+    afterEach(function() {
+      jasmine.clock().uninstall();
+    });
+
+    it('should start polling', function() {
+      spyOn(this.model.poller, 'start');
+
       this.model.pollCheck();
+
+      expect(this.model.poller.start).toHaveBeenCalled();
+    });
+  });
+
+  describe('.destroyCheck', function() {
+
+    beforeEach(function() {
+      jasmine.clock().install();
+      spyOn(this.model, 'fetch');
     });
 
-    it('should stop polling when geocoding has failed', function(done) {
-      var self = this;
-      setTimeout(function(){
-        self.model.set('state', 'failed');
-        expect(self.model.fetch.calls.count()).toBe(1);
-        expect(self.model.pollTimer).toBeUndefined();
-        done();
-      }, 2000);
+    afterEach(function() {
+      jasmine.clock().uninstall();
     });
 
-    it('should stop polling when geocoding has completed', function(done) {
-      var self = this;
-      setTimeout(function(){
-        self.model.set('state', 'finished');
-        expect(self.model.fetch.calls.count()).toBe(1);
-        expect(self.model.pollTimer).toBeUndefined();
-        done();
-      }, 2000);
+    it('should stop polling', function() {
+      spyOn(this.model.poller, 'stop');
+
+      this.model.pollCheck();
+      this.model.destroyCheck();
+
+      expect(this.model.poller.stop).toHaveBeenCalled();
     });
   });