Avoid using Object.keys(obj).length in hot code paths

Complexity of Object.keys(obj).length is O(n) where n is the number of
object keys. Unfortunately, JavaScript have no built-in means of
determining number of object keys in constant time. Therefore, we have
to count object keys using separate counter variable.

It may look ugly (and indeed it is), but it greatly improves smoothness
and overall feel of IITC.

code/debugging.js

@@ -5,9 +5,9 @@
 window.debug = function() {}
 
 window.debug.renderDetails = function() {
-  console.log('portals: ' + Object.keys(portals).length);
+  console.log('portals: ' + window.portalsCount);
-  console.log('links:   ' + Object.keys(links).length);
+  console.log('links:   ' + window.linksCount);
-  console.log('fields:  ' + Object.keys(fields).length);
+  console.log('fields:  ' + window.fieldsCount);
 }
 
 window.debug.printStackTrace = function() {

code/map_data.js

@@ -572,7 +572,7 @@ window.getMarker = function(ent, portalLevel, latlng, team) {
 
 // renders a portal on the map from the given entity
 window.renderPortal = function(ent) {
-  if(Object.keys(portals).length >= MAX_DRAWN_PORTALS && ent[0] !== selectedPortal)
+  if(window.portalsCount >= MAX_DRAWN_PORTALS && ent[0] !== selectedPortal)
     return removeByGuid(ent[0]);
 
   // hide low level portals on low zooms
@@ -633,6 +633,7 @@ window.renderPortal = function(ent) {
         removeByGuid(portalResonatorGuid(portalGuid, i));
     }
     delete window.portals[portalGuid];
+    window.portalsCount --;
     if(window.selectedPortal === portalGuid) {
       window.unselectOldPortal();
     }
@@ -642,6 +643,7 @@ window.renderPortal = function(ent) {
     // enable for debugging
     if(window.portals[this.options.guid]) throw('duplicate portal detected');
     window.portals[this.options.guid] = this;
+    window.portalsCount ++;
 
     window.renderResonators(this.options.guid, this.options.details, this);
     // handles the case where a selected portal gets removed from the
@@ -781,7 +783,7 @@ window.resonatorsSetStyle = function(portalGuid, resoStyle, lineStyle) {
 
 // renders a link on the map from the given entity
 window.renderLink = function(ent) {
-  if(Object.keys(links).length >= MAX_DRAWN_LINKS)
+  if(window.linksCount >= MAX_DRAWN_LINKS)
     return removeByGuid(ent[0]);
 
   // some links are constructed from portal linkedEdges data. These have no valid 'creator' data.
@@ -823,11 +825,15 @@ window.renderLink = function(ent) {
 
   if(!getPaddedBounds().intersects(poly.getBounds())) return;
 
-  poly.on('remove', function() { delete window.links[this.options.guid]; });
+  poly.on('remove', function() {
+    delete window.links[this.options.guid]; 
+    window.linksCount--;
+  });
   poly.on('add',    function() {
     // enable for debugging
     if(window.links[this.options.guid]) throw('duplicate link detected');
     window.links[this.options.guid] = this;
+    window.linksCount++;
     this.bringToBack();
   });
   poly.addTo(linksLayer);
@@ -835,7 +841,7 @@ window.renderLink = function(ent) {
 
 // renders a field on the map from a given entity
 window.renderField = function(ent) {
-  if(Object.keys(fields).length >= MAX_DRAWN_FIELDS)
+  if(window.fieldsCount >= MAX_DRAWN_FIELDS)
     return window.removeByGuid(ent[0]);
 
   var old = findEntityInLeaflet(fieldsLayer, window.fields, ent[0]);
@@ -921,11 +927,15 @@ window.renderField = function(ent) {
   // events, thus this listener will be attached to the field. It
   // doesn’t matter to which element these are bound since Leaflet
   // will add/remove all elements of the LayerGroup at once.
-  poly.on('remove', function() { delete window.fields[this.options.guid]; });
+  poly.on('remove', function() {
+    delete window.fields[this.options.guid];
+    window.fieldsCount--;
+  });
   poly.on('add',    function() {
     // enable for debugging
     if(window.fields[this.options.guid]) console.warn('duplicate field detected');
     window.fields[this.options.guid] = f;
+    window.fieldsCount++;
     this.bringToBack();
   });
   f.addTo(fieldsLayer);

code/portal_render_limit.js

@@ -41,6 +41,7 @@ window.portalRenderLimit.previousMinLevel = -1;
 window.portalRenderLimit.previousZoomLevel = null;
 window.portalRenderLimit.newPortalsPerLevel = new Array(MAX_PORTAL_LEVEL + 1);
 window.portalRenderLimit.portalsLowerThanPrevMinLv = new Array(MAX_PORTAL_LEVEL + 1);
+window.portalRenderLimit.portalsLowerThanPrevMinLvCnt = new Array(MAX_PORTAL_LEVEL + 1);
 
 window.portalRenderLimit.init = function () {
   var currentZoomLevel = map.getZoom();
@@ -72,6 +73,7 @@ window.portalRenderLimit.resetCounting = function() {
 window.portalRenderLimit.resetPortalsLowerThanPrevMinLv = function() {
   for(var i = 0; i <= MAX_PORTAL_LEVEL; i++) {
     portalRenderLimit.portalsLowerThanPrevMinLv[i] = {};
+    portalRenderLimit.portalsLowerThanPrevMinLvCnt[i] = 0;
   }
 }
 
@@ -125,6 +127,7 @@ window.portalRenderLimit.splitLowLevelPortals = function(portals) {
 
     if(!portalOnMap && portalLevel < portalRenderLimit.previousMinLevel) {
       portalRenderLimit.portalsLowerThanPrevMinLv[portalLevel][guid] = portal;
+      portalRenderLimit.portalsLowerThanPrevMinLvCnt[portalLevel]++;
     } else {
       resultPortals[guid] = portal;
     }
@@ -158,7 +161,7 @@ window.portalRenderLimit.setMinLevel = function() {
   // Find the min portal level under render limit
   while(newMinLevel > 0) {
     var oldPortalCount = layerGroupLength(portalsLayers[newMinLevel - 1]);
-    var storedPortalCount = Object.keys(portalRenderLimit.portalsLowerThanPrevMinLv[newMinLevel - 1]).length;
+    var storedPortalCount = portalRenderLimit.portalsLowerThanPrevMinLvCnt[newMinLevel - 1];
     var newPortalCount = Math.max(storedPortalCount, portalRenderLimit.newPortalsPerLevel[newMinLevel - 1]);
 
     totalPortalsCount += oldPortalCount + newPortalCount;

code/utils_misc.js

@@ -245,9 +245,9 @@ window.getPaddedBounds = function() {
 // cally detect if the render limit will be hit.
 window.renderLimitReached = function(ratio) {
   ratio = ratio || 1;
-  if(Object.keys(portals).length*ratio >= MAX_DRAWN_PORTALS) return true;
+  if(window.portalsCount*ratio >= MAX_DRAWN_PORTALS) return true;
-  if(Object.keys(links).length*ratio >= MAX_DRAWN_LINKS) return true;
+  if(window.linksCount*ratio >= MAX_DRAWN_LINKS) return true;
-  if(Object.keys(fields).length*ratio >= MAX_DRAWN_FIELDS) return true;
+  if(window.fieldsCount*ratio >= MAX_DRAWN_FIELDS) return true;
   var param = { 'reached': false };
   window.runHooks('checkRenderLimit', param);
   return param.reached;

main.js

@@ -250,8 +250,11 @@ var portalsLayers, linksLayer, fieldsLayer;
 // automatically kept in sync with the items on *sLayer, so never ever
 // write to them.
 window.portals = {};
+window.portalsCount = 0;
 window.links = {};
+window.linksCount = 0;
 window.fields = {};
+window.fieldsCount = 0;
 window.resonators = {};
 
 // contain current status(on/off) of overlay layerGroups.