shapeObj buffer resize algorithm

[Kovacs Baldvin]

Hi!

I've attached a patch that makes the msAddLines variants to use
relocate, but without introducing the manual heuristic. I think
it is the reasonable solution...

Best regards,
Baldvin Kovacs

-------------------------

Below are the profiling results. For every test case 100 runs
were made and the results cumulated. All of them was compiled 
with -O2 -pg

1. With this patch included:

  %   cumulative   self              self     total           
 time   seconds   seconds    calls  ms/call  ms/call  name    
 17.79      4.67     4.67      100    46.70    46.70  msImageCopyMerge
 14.63      8.51     3.84      200    19.20    19.20  msImageInitGD
...
  3.85     19.46     1.01  3120400     0.00     0.00  msAddLine

2. With the bufsize *= 2 heuristic:

  %   cumulative   self              self     total           
 time   seconds   seconds    calls  ms/call  ms/call  name    
 18.69      4.87     4.87      100    48.70    48.70  msImageCopyMerge
 14.51      8.65     3.78      200    18.90    18.90  msImageInitGD
...
  2.99     19.79     0.78  3120400     0.00     0.00  msAddLine
...
  0.31     24.75     0.08   441600     0.00     0.00  msShapeObjIncBuffer

3. cvs version:

  %   cumulative   self              self     total           
 time   seconds   seconds    calls   s/call   s/call  name    
 86.61    163.87   163.87  3120400     0.00     0.00  msAddLine
  2.53    168.66     4.79      100     0.05     0.05  msImageCopyMerge
  1.99    172.42     3.76      200     0.02     0.02  msImageInitGD

-------------- next part --------------
Index: mapprimitive.c
===================================================================
RCS file: /data2/cvsroot/mapserver/mapprimitive.c,v
retrieving revision 1.53
diff -u -r1.53 mapprimitive.c
--- mapprimitive.c	14 Jun 2005 16:03:34 -0000	1.53
+++ mapprimitive.c	27 Jul 2005 14:01:26 -0000
@@ -1,4 +1,4 @@
-/******************************************************************************
+ /******************************************************************************
  *
  * Project:  MapServer
  * Purpose:  Implementations for rectObj, pointObj, lineObj, shapeObj, etc.
@@ -254,35 +254,27 @@
 int msAddLine(shapeObj *p, lineObj *new_line)
 {
   int c;
-  lineObj *extended_line;
 
   /* Create an extended line array */
-  if((extended_line = (lineObj *)malloc((p->numlines + 1) * sizeof(lineObj))) == NULL) {
+  p->line = (lineObj *)realloc(p->line, (p->numlines + 1) * sizeof(lineObj));
+  if( p->line == NULL ) {
     msSetError(MS_MEMERR, NULL, "msAddLine()");
     return(MS_FAILURE);
   }
 
-  /* Copy the old line into the extended line array */
-  for (c= 0; c < p->numlines; c++)
-    extended_line[c]= p->line[c];
-
   /* Copy the new line onto the end of the extended line array */
-  c= p->numlines;
-  extended_line[c].numpoints = new_line->numpoints;  
-  if((extended_line[c].point = (pointObj *)malloc(new_line->numpoints * sizeof(pointObj))) == NULL) {
+  c = p->numlines;
+  p->line[c].numpoints = new_line->numpoints;  
+  if((p->line[c].point = (pointObj *)malloc(new_line->numpoints * sizeof(pointObj))) == NULL) {
     msSetError(MS_MEMERR, NULL, "msAddLine()");
     return(MS_FAILURE);
   }
 
-  memcpy( extended_line[c].point, new_line->point, 
+  memcpy( p->line[c].point, new_line->point, 
           sizeof(pointObj) * new_line->numpoints );
 
-  /* Dispose of the old line */
-  if(p->line) free(p->line);
-
   /* Update the polygon information */
   p->numlines++;
-  p->line = extended_line;
 
   return(MS_SUCCESS);
 }
@@ -294,33 +286,25 @@
 int msAddLineDirectly(shapeObj *p, lineObj *new_line)
 {
   int c;
-  lineObj *extended_line;
 
   /* Create an extended line array */
-  if((extended_line = (lineObj *)malloc((p->numlines + 1) * sizeof(lineObj))) == NULL) {
+  p->line = (lineObj *)realloc(p->line, (p->numlines + 1) * sizeof(lineObj));
+  if( p->line == NULL ) {
     msSetError(MS_MEMERR, NULL, "msAddLine()");
     return(MS_FAILURE);
   }
 
-  /* Copy the old line into the extended line array */
-  for (c= 0; c < p->numlines; c++)
-    extended_line[c]= p->line[c];
-
   /* Copy the new line onto the end of the extended line array */
   c= p->numlines;
-  extended_line[c].numpoints = new_line->numpoints;  
-  extended_line[c].point = new_line->point;
+  p->line[c].numpoints = new_line->numpoints;  
+  p->line[c].point = new_line->point;
 
   /* strip points reference off the passed in lineObj */
   new_line->point = NULL;
   new_line->numpoints = 0;
 
-  /* Dispose of the old line */
-  if(p->line) free(p->line);
-
   /* Update the polygon information */
   p->numlines++;
-  p->line = extended_line;
 
   return(MS_SUCCESS);
 }