Add configuration attribute for activating this optimization

Author: jbo-ads

include/mapcache.h

@@ -1578,6 +1578,7 @@ MS_DLL_EXPORT apr_array_header_t *mapcache_requested_dimensions_clone(apr_pool_t
 struct mapcache_dimension {
   mapcache_dimension_type type;
   int isTime;
+  int wms_single_query_minzoom;
   char *name;
   char *unit;
   apr_table_t *metadata;

lib/configuration_xml.c

@@ -63,6 +63,7 @@ void parseMetadata(mapcache_context *ctx, ezxml_t node, apr_table_t *metadata)
 void parseDimensions(mapcache_context *ctx, ezxml_t node, mapcache_tileset *tileset)
 {
   ezxml_t dimension_node;
+  ezxml_t wms_single_query_node;
   apr_array_header_t *dimensions = apr_array_make(ctx->pool,1,sizeof(mapcache_dimension*));
   for(dimension_node = ezxml_child(node,"dimension"); dimension_node; dimension_node = dimension_node->next) {
     char *name = (char*)ezxml_attr(dimension_node,"name");
@@ -120,6 +121,26 @@ void parseDimensions(mapcache_context *ctx, ezxml_t node, mapcache_tileset *tile
       return;
     }
 
+    dimension->wms_single_query_minzoom = -1;
+    wms_single_query_node = ezxml_child(dimension_node,"wms_single_query");
+    if (wms_single_query_node && wms_single_query_node->txt) {
+      if (!strcasecmp(wms_single_query_node->txt,"true")) {
+        const char * minzoom = ezxml_attr(wms_single_query_node,"minzoom");
+        dimension->wms_single_query_minzoom = 0;
+        if (minzoom && *minzoom) {
+          char *endptr;
+          dimension->wms_single_query_minzoom = strtol(minzoom,&endptr,10);
+          if (*endptr != 0 || dimension->wms_single_query_minzoom < 0) {
+            ctx->set_error(ctx, 400, "failed to parse minzoom \"%s\" for <wms_single_query>"
+                "expecting an integer starting from 0",minzoom);
+            return;
+          }
+        }
+      } else if (strcasecmp(wms_single_query_node->txt,"false")) {
+        ctx->set_error(ctx,400,"failed to parse <wms_single_query> (%s), expecting \"true\" or \"false\"",wms_single_query_node->txt);
+        return;
+      }
+    }
 
     dimension->configuration_parse_xml(ctx,dimension,dimension_node);
     GC_CHECK_ERROR(ctx);

lib/tileset.c

@@ -221,24 +221,27 @@ void mapcache_tileset_get_map_tiles(mapcache_context *ctx, mapcache_tileset *til
   resolution = mapcache_grid_get_resolution(bbox, width, height);
   *effectively_used_grid_link = mapcache_grid_get_closest_wms_level(ctx,grid_link,resolution,&level);
 
-  // Get dimensions values
+  /* we don't want to assemble tiles that have already been reassembled from a lower level */
+  if((*effectively_used_grid_link)->outofzoom_strategy == MAPCACHE_OUTOFZOOM_REASSEMBLE && level > (*effectively_used_grid_link)->max_cached_zoom) {
+    level = (*effectively_used_grid_link)->max_cached_zoom;
+  }
+
+  // Get dimensions values for whole map if required by <wms_single_query> configuration
   if (dimensions)
   {
     int j;
     for (j=0 ; j<dimensions->nelts ; j++)
     {
       mapcache_requested_dimension *rdim = APR_ARRAY_IDX(dimensions,j,mapcache_requested_dimension*);
-      rdim->cached_entries_for_value =
-        mapcache_dimension_get_entries_for_value(ctx,rdim->dimension,rdim->requested_value,
-            tileset,bbox,(*effectively_used_grid_link)->grid);
+      mapcache_dimension *dim = rdim->dimension;
+      if (dim->wms_single_query_minzoom != -1 && level >= dim->wms_single_query_minzoom) {
+        rdim->cached_entries_for_value =
+          mapcache_dimension_get_entries_for_value(ctx,rdim->dimension,rdim->requested_value,
+              tileset,bbox,(*effectively_used_grid_link)->grid);
+      }
     }
   }
 
-  /* we don't want to assemble tiles that have already been reassembled from a lower level */
-  if((*effectively_used_grid_link)->outofzoom_strategy == MAPCACHE_OUTOFZOOM_REASSEMBLE && level > (*effectively_used_grid_link)->max_cached_zoom) {
-    level = (*effectively_used_grid_link)->max_cached_zoom;
-  }
-
   mapcache_grid_get_xy(ctx,(*effectively_used_grid_link)->grid,bbox->minx,bbox->miny,level,&bl_x,&bl_y);
   mapcache_grid_get_xy(ctx,(*effectively_used_grid_link)->grid,bbox->maxx,bbox->maxy,level,&tr_x,&tr_y);
   Mx = MAPCACHE_MAX(MAPCACHE_MIN(MAPCACHE_MAX(tr_x,bl_x),(*effectively_used_grid_link)->grid_limits[level].maxx),(*effectively_used_grid_link)->grid_limits[level].minx);