[babl] babl: make pixel-count instrumentation opt-in

[Øyvind Kolås <ok src gnome org>]

commit 20d3b800dc7972897a5fa89bb664227c7d043111
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jan 17 03:46:59 2018 +0100

    babl: make pixel-count instrumentation opt-in
    
    Checking if an integer is 0/1 is lower overhead than incrementing a long stored
    kt a memory location. As a side effect, the entries in
    ~/.cache/babl/babl-fishes will not be sorted by most used to least used unless
    the BABL_INSTRUMENT environment variable is set to a value.

 babl/babl-fish-path.c |   15 ++++++++++++---
 babl/babl-internal.h  |    4 +++-
 2 files changed, 15 insertions(+), 4 deletions(-)
---
diff --git a/babl/babl-fish-path.c b/babl/babl-fish-path.c
index 867cb8d..eb10fe9 100644
--- a/babl/babl-fish-path.c
+++ b/babl/babl-fish-path.c
@@ -99,6 +99,7 @@ _babl_fish_create_name (char       *buf,
 static int max_path_length (void);
 
 static int debug_conversions = 0;
+int _babl_instrument = 0;
 
 double _babl_legal_error (void)
 {
@@ -120,6 +121,12 @@ double _babl_legal_error (void)
   else
     debug_conversions = 0;
 
+  env = getenv ("BABL_INSTRUMENT");
+  if (env && env[0] != '\0')
+    _babl_instrument = 1;
+  else
+    _babl_instrument = 0;
+
   return error;
 }
 
@@ -732,8 +739,9 @@ _babl_process (const Babl *cbabl,
                long        n)
 {
   Babl *babl = (void*)cbabl;
-  babl->fish.pixels += n;
   babl->fish.dispatch (babl, source, destination, n, *babl->fish.data);
+  if (_babl_instrument)
+    babl->fish.pixels += n;
   return n;
 }
 
@@ -765,7 +773,8 @@ babl_process_rows (const Babl *fish,
   if (n <= 0)
     return 0;
 
-  babl->fish.pixels += n * rows;
+  if (_babl_instrument)
+    babl->fish.pixels += n * rows;
   for (row = 0; row < rows; row++)
     {
       babl->fish.dispatch (babl, (void*)src, (void*)dst, n, *babl->fish.data);
@@ -996,7 +1005,7 @@ get_path_instrumentation (FishPathInstrumentation *fpi,
   process_conversion_path (path, fpi->source, source_bpp, fpi->destination,
                            dest_bpp, fpi->num_test_pixels);
   ticks_end = babl_ticks ();
-  *path_cost = ticks_end - ticks_start;
+  *path_cost = (ticks_end - ticks_start);
 
   /* transform the reference and the actual destination buffers to RGBA
    * for comparison with each other
diff --git a/babl/babl-internal.h b/babl/babl-internal.h
index ff83795..415bc5e 100644
--- a/babl/babl-internal.h
+++ b/babl/babl-internal.h
@@ -483,6 +483,7 @@ void babl_space_to_xyz   (const Babl *space, const double *rgb, double *xyz);
  */
 void babl_space_from_xyz (const Babl *space, const double *xyz, double *rgb);
 
+extern int _babl_instrument;
 
 static inline void
 babl_conversion_process (const Babl *babl,
@@ -491,7 +492,8 @@ babl_conversion_process (const Babl *babl,
                          long        n)
 {
   BablConversion *conversion = (BablConversion *) babl;
-  conversion->pixels += n;
+  if (_babl_instrument)
+    conversion->pixels += n;
   conversion->dispatch (babl, source, destination, n, conversion->data);
 }