Updating tileJson provider to use webworkers to process tiles when they are available. This is probably still not as efficient as it could be as we are not recycling workers.

lib/torque/provider/tilejson.js

@@ -48,10 +48,39 @@
      *   Index: Array index to the properties
      * }
      */
-    proccessTile: function(rows, coord, zoom) {
+    createProccessTileWorker:function(){
+      var workerFunction = "var proccessTile ="+ this.proccessTileSerial.toString()
+      var wrapper = "; self.onmessage = function(e){var data = JSON.parse(e.data); JSON.stringify(self.postMessage(proccessTile(data.rows,data.coord, data.zoom, data.options)))}"
+      var script = workerFunction + wrapper;
+      var blob = new Blob([script], {type: "text/javascript"})
+      var worker  = new Worker(window.URL.createObjectURL(blob))
+      return worker
+    },
+    proccessTile:function(rows,coord,zoom,callback){
+      if(typeof(Worker) === "undefined"){
+        callback(this.proccessTileSerial(rows,coord,zoom, this.options))
+      }
+      else{
+        var worker = this.createProccessTileWorker()
+        worker.onmessage = function(e){
+          callback(e.data)
+          worker.terminate()
+        }
+
+        var workerSafeOptions= {
+          x : new this.options.coordinates_data_type(rows.length),
+          y : new this.options.coordinates_data_type(rows.length),
+          cumulative: this.options.cumulative,
+          valueDataType: this.options.valueDataType,
+          resolution: this.options.resolution,
+        }
+        worker.postMessage(JSON.stringify({rows: rows, coord: {x:coord.x,y:coord.y}, zoom:zoom, options: workerSafeOptions}))
+      }
+    },
+    proccessTileSerial: function(rows, coord, zoom,options) {
       var r;
-      var x = new this.options.coordinates_data_type(rows.length);
+      var x = options.x || new options.coordinates_data_type(rows.length);
-      var y = new this.options.coordinates_data_type(rows.length);
+      var y = options.y || new options.coordinates_data_type(rows.length);
 
       // count number of dates
       var dates = 0;
@@ -64,16 +93,16 @@
         }
       }
 
-      if(this.options.cumulative) {
+      if(options.cumulative) {
         dates = (1 + maxDateSlots) * rows.length;
       }
 
-      var type = this.options.cumulative ? Uint32Array: Uint8ClampedArray;
+      var type = options.cumulative ? Uint32Array: Uint8ClampedArray;
 
       // reserve memory for all the dates
       var timeIndex = new Int32Array(maxDateSlots + 1); //index-size
       var timeCount = new Int32Array(maxDateSlots + 1);
-      var renderData = new (this.options.valueDataType || type)(dates);
+      var renderData = new (options.valueDataType || type)(dates);
       var renderDataPos = new Uint32Array(dates);
 
       var rowsPerSlot = {};
@@ -81,15 +110,15 @@
       // precache pixel positions
       for (var r = 0; r < rows.length; ++r) {
         var row = rows[r];
-        x[r] = row.x__uint8 * this.options.resolution;
+        x[r] = row.x__uint8 * options.resolution;
-        y[r] = row.y__uint8 * this.options.resolution;
+        y[r] = row.y__uint8 * options.resolution;
 
         var dates = row.dates__uint16;
         var vals = row.vals__uint8;
-        if (!this.options.cumulative) {
+        if (!options.cumulative) {
           for (var j = 0, len = dates.length; j < len; ++j) {
               var rr = rowsPerSlot[dates[j]] || (rowsPerSlot[dates[j]] = []);
-              if(this.options.cumulative) {
+              if(options.cumulative) {
                   vals[j] += prev_val;
               }
               prev_val = vals[j];
@@ -152,7 +181,7 @@
       };
     },
 
-    setSteps: function(steps, opt) { 
+    setSteps: function(steps, opt) {
       opt = opt || {};
       if (this.options.steps !== steps) {
         this.options.steps = steps;
@@ -257,7 +286,7 @@
       torque.net.get( url , function (data) {
         if (data && data.responseText) {
           var rows = JSON.parse(data.responseText);
-          callback(self.proccessTile(rows, coord, zoom));
+          self.proccessTile(rows, coord, zoom,callback.bind(self));
         } else {
           callback(null);
         }
@@ -314,6 +343,7 @@
 
     _fetchMap: function(callback) {
       var self = this;
+
       torque.net.get(this.options.tileJSON, function (data) {
         data = JSON.parse(data.response);
         if (data) {
@@ -334,4 +364,4 @@
     }
   };
 
-  module.exports = tileJSON;
+  module.exports = tileJSON;