(#2026) fix performance regression in geography distance calculation

git-svn-id: http://svn.osgeo.org/postgis/trunk@10531 b70326c6-7e19-0410-871a-916f4a2858ee

NEWS

@@ -83,6 +83,7 @@ PostGIS 2.1.0
   - #1957, ST_Distance to a one-point LineString returns NULL 
   - #1976, Geography point-in-ring code overhauled for more reliability
   - #1981, cleanup of unused variables causing warnings with gcc 4.6+
+  - #2026, improve performance of distance calculations 
   - #2057, Fixed linking issue for raster2psql to libpq
 
 PostGIS 2.0.1

liblwgeom/g_box.c

@@ -26,6 +26,12 @@ void gbox_init(GBOX *gbox)
 	memset(gbox, 0, sizeof(GBOX));
 }
 
+GBOX* gbox_clone(const GBOX *gbox)
+{
+	GBOX *g = lwalloc(sizeof(GBOX));
+	memcpy(g, gbox, sizeof(GBOX));
+	return g;
+}
 
 /* TODO to be removed */
 BOX3D* box3d_from_gbox(const GBOX *gbox)

liblwgeom/liblwgeom.h.in

@@ -681,6 +681,10 @@ extern void lwgeom_drop_srid(LWGEOM *lwgeom);
  * NULL if the geometry is empty.
  */
 extern void lwgeom_add_bbox(LWGEOM *lwgeom);
+/**
+* Compute a box for geom and all sub-geometries, if not already computed
+*/
+extern void lwgeom_add_bbox_deep(LWGEOM *lwgeom, GBOX *gbox);
 
 /** 
  * Get a non-empty geometry bounding box, computing and

liblwgeom/liblwgeom_internal.h

@@ -330,6 +330,7 @@ GBOX *box2d_clone(const GBOX *lwgeom);
 LWLINE *lwline_clone_deep(const LWLINE *lwgeom);
 LWPOLY *lwpoly_clone_deep(const LWPOLY *lwgeom);
 LWCOLLECTION *lwcollection_clone_deep(const LWCOLLECTION *lwgeom);
+GBOX *gbox_clone(const GBOX *gbox);
 
 /*
 * Startpoint

liblwgeom/lwgeom.c

@@ -565,14 +565,43 @@ void
 lwgeom_add_bbox(LWGEOM *lwgeom)
 {
 	/* an empty LWGEOM has no bbox */
-	if( lwgeom_is_empty(lwgeom) ) return;
+	if ( lwgeom_is_empty(lwgeom) ) return;
 
 	if ( lwgeom->bbox ) return;
 	FLAGS_SET_BBOX(lwgeom->flags, 1);
 	lwgeom->bbox = gbox_new(lwgeom->flags);
 	lwgeom_calculate_gbox(lwgeom, lwgeom->bbox);
 }
 
+void 
+lwgeom_add_bbox_deep(LWGEOM *lwgeom, GBOX *gbox)
+{
+	if ( lwgeom_is_empty(lwgeom) ) return;
+
+	FLAGS_SET_BBOX(lwgeom->flags, 1);
+
+	if ( ! ( gbox || lwgeom->bbox ) )
+	{
+		lwgeom->bbox = gbox_new(lwgeom->flags);
+		lwgeom_calculate_gbox(lwgeom, lwgeom->bbox);		
+	}
+	else if ( gbox && ! lwgeom->bbox )
+	{
+		lwgeom->bbox = gbox_clone(gbox);
+	}
+
+	if ( lwgeom_is_collection(lwgeom) )
+	{
+		int i;
+		LWCOLLECTION *lwcol = (LWCOLLECTION*)lwgeom;
+
+		for ( i = 0; i < lwcol->ngeoms; i++ )
+		{
+			lwgeom_add_bbox_deep(lwcol->geoms[i], lwgeom->bbox);
+		}
+	}
+}
+
 const GBOX *
 lwgeom_get_bbox(const LWGEOM *lwg)
 {

postgis/geography_measurement.c

@@ -87,6 +87,10 @@ Datum geography_distance_uncached(PG_FUNCTION_ARGS)
 		PG_RETURN_NULL();
 	}
 
+	/* Make sure we have boxes attached */
+	lwgeom_add_bbox_deep(lwgeom1, NULL);
+	lwgeom_add_bbox_deep(lwgeom2, NULL);
+
 	distance = lwgeom_distance_spheroid(lwgeom1, lwgeom2, &s, FP_TOLERANCE);
 
 	/* Clean up */