[Git][freetype/freetype-demos][master] [graph] Count the number of hash clashes.

[Alexei Podtelezhnikov (@apodtele)]

Alexei Podtelezhnikov pushed to branch master at FreeType / FreeType Demo Programs

Commits:

• ecaa7996
  by Alexei Podtelezhnikov at 2022-08-22T23:08:10-04:00

  [graph] Count the number of hash clashes.
  
  The hash table lookups take very noticeable time when rendering is
  complex like in `ftgrid`.  This can help optimize the hash function.
  
  * graph/gblender.h (GBLENDER_STATS): New field for clashes.
  * graph/gblender.c (gblender_init, gblender_lookup{,_channel},
  gblender_dump_stats): Initialize, collect, and report clashes.
  

2 changed files:

• graph/gblender.c
• graph/gblender.h

Changes:

graph/gblender.c

---

...	...	@@ -167,6 +167,7 @@ gblender_init( GBlender blender,
167	167	#ifdef GBLENDER_STATS
168	168	blender->stat_hits = 0;
169	169	blender->stat_lookups = 0;
	170	+ blender->stat_clashes = 0;
170	171	blender->stat_keys = 0;
171	172	blender->stat_clears = 0;
172	173	#endif
...	...	@@ -308,6 +309,9 @@ NewNode:
308	309	#endif
309	310
310	311	Exit:
	312	+#ifdef GBLENDER_STATS
	313	+ blender->stat_clashes += ( idx - idx0 ) & (GBLENDER_KEY_COUNT-1);
	314	+#endif
311	315	return key->cells;
312	316	}
313	317
...	...	@@ -399,6 +403,9 @@ NewNode:
399	403	#endif
400	404
401	405	Exit:
	406	+#ifdef GBLENDER_STATS
	407	+ blender->stat_clashes += ( idx - idx0 ) & (GBLENDER_KEY_COUNT-1);
	408	+#endif
402	409	return (unsigned char*)blender->cells + key->index;
403	410	}
404	411
...	...	@@ -421,6 +428,7 @@ gblender_dump_stats( GBlender blender )
421	428	blender->stat_lookups,
422	429	blender->stat_lookups - blender->stat_keys,
423	430	blender->stat_lookups );
	431	+ printf( " Clashes: %ld\n", blender->stat_clashes );
424	432	printf( " Keys used: %ld\n Caches full: %ld\n",
425	433	blender->stat_keys, blender->stat_clears );
426	434	}

graph/gblender.h

---

...	...	@@ -107,6 +107,7 @@
107	107	#ifdef GBLENDER_STATS
108	108	long stat_hits; /* number of direct hits */
109	109	long stat_lookups; /* number of table lookups */
	110	+ long stat_clashes; /* number of table clashes */
110	111	long stat_keys; /* number of table key recomputation */
111	112	long stat_clears; /* number of table clears */
112	113	#endif

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