msDrawMap(): optimize pre-processing of WMS/WFS layers

Currently we use msLayerIsVisible() to determine how many potential WMS/WFS
layers there are. But this is a costly operation. Rather test the connectiontype,
and defer testing msLayerIsVisible() as late as possible.

Author: rouault

mapdraw.c

@@ -220,7 +220,8 @@ imageObj *msDrawMap(mapObj *map, int querymap)
 #if defined(USE_WMS_LYR) || defined(USE_WFS_LYR)
   enum MS_CONNECTION_TYPE lastconnectiontype;
   httpRequestObj *pasOWSReqInfo=NULL;
-  int numOWSLayers=0, numOWSRequests=0;
+  int numOWSLayers=0;
+  int numOWSRequests=0;
   wmsParamsObj sLastWMSParams;
 #endif
 
@@ -256,30 +257,43 @@ imageObj *msDrawMap(mapObj *map, int querymap)
    */
   numOWSLayers=0;
   for(i=0; i<map->numlayers; i++) {
-    if(map->layerorder[i] != -1 &&
-        msLayerIsVisible(map, GET_LAYER(map,map->layerorder[i])))
+      if(map->layerorder[i] == -1 )
+        continue;
+
+      lp = GET_LAYER(map,map->layerorder[i]);
+      if( lp->connectiontype != MS_WMS &&
+          lp->connectiontype != MS_WFS ) {
+        continue;
+      }
       numOWSLayers++;
   }
 
-
   if (numOWSLayers > 0) {
+
     /* Alloc and init pasOWSReqInfo...
      */
-    pasOWSReqInfo = (httpRequestObj *)malloc((numOWSLayers+1)*sizeof(httpRequestObj));
+    pasOWSReqInfo = (httpRequestObj *)malloc(numOWSLayers*sizeof(httpRequestObj));
     if (pasOWSReqInfo == NULL) {
       msSetError(MS_MEMERR, "Allocation of httpRequestObj failed.", "msDrawMap()");
       return NULL;
     }
-    msHTTPInitRequestObj(pasOWSReqInfo, numOWSLayers+1);
+    msHTTPInitRequestObj(pasOWSReqInfo, numOWSLayers);
     msInitWmsParamsObj(&sLastWMSParams);
 
     /* Pre-download all WMS/WFS layers in parallel before starting to draw map */
     lastconnectiontype = MS_SHAPEFILE;
-    for(i=0; numOWSLayers && i<map->numlayers; i++) {
-      if(map->layerorder[i] == -1 || !msLayerIsVisible(map, GET_LAYER(map,map->layerorder[i])))
+    for(i=0; i<map->numlayers; i++) {
+      if(map->layerorder[i] == -1 )
         continue;
 
       lp = GET_LAYER(map,map->layerorder[i]);
+      if( lp->connectiontype != MS_WMS &&
+          lp->connectiontype != MS_WFS ) {
+        continue;
+      }
+
+      if( !msLayerIsVisible(map, lp) )
+        continue;
 
 #ifdef USE_WMS_LYR
       if(lp->connectiontype == MS_WMS) {
@@ -306,9 +320,7 @@ imageObj *msDrawMap(mapObj *map, int querymap)
       lastconnectiontype = lp->connectiontype;
     }
 
-#ifdef USE_WMS_LYR
     msFreeWmsParamsObj(&sLastWMSParams);
-#endif
   } /* if numOWSLayers > 0 */
 
   if(numOWSRequests && msOWSExecuteRequests(pasOWSReqInfo, numOWSRequests, map, MS_TRUE) == MS_FAILURE) {

maphttp.c

@@ -113,11 +113,6 @@ void msHTTPCleanup()
  * Should be called on a new array of httpRequestObj to initialize them
  * for use with msHTTPExecuteRequest(), etc.
  *
- * Note that users of this module should always allocate and init one
- * more instance of httpRequestObj in their array than what they plan to
- * use because the terminate_handler() needs the last entry in the array
- * to have reqObj->request == NULL
- *
  **********************************************************************/
 void msHTTPInitRequestObj(httpRequestObj *pasReqInfo, int numRequests)
 {