Add PH stats for secondary hash key vector lengths.

src/ph.c

@@ -458,6 +458,7 @@ PH_Stats(const struct ph * const restrict ph,
 
 	stats->h2buckets_min = UINT64_MAX;
 	stats->h2strings_min = UINT64_MAX;
+	stats->h2klen_min = SIZE_MAX;
 	for (unsigned i = 0; i <= ph->h1->mask; i++)
 		if (vbit_test(ph->collision, i)) {
 			struct hash *h2;
@@ -476,6 +477,14 @@ PH_Stats(const struct ph * const restrict ph,
 				((double)sz - stats->h2buckets_avg)
 				/ (double)stats->collisions;
 
+			if (h2->l < stats->h2klen_min)
+				stats->h2klen_min = h2->l;
+			if (h2->l > stats->h2klen_max)
+				stats->h2klen_max = h2->l;
+			stats->h2klen_avg +=
+				((double)h2->l - stats->h2klen_avg)
+				/ (double)stats->collisions;
+
 			for (unsigned j = 0; j < sz; j++) {
 				if (h2->tbl[j] == UINT_MAX)
 					continue;
@@ -493,6 +502,8 @@ PH_Stats(const struct ph * const restrict ph,
 		stats->h2buckets_min = 0;
 	if (stats->h2strings_min == UINT64_MAX)
 		stats->h2strings_min = 0;
+	if (stats->h2klen_min == SIZE_MAX)
+		stats->h2klen_min = 0;
 }
 
 void

src/ph.h

@@ -56,6 +56,9 @@ struct ph_stats {
 	uint64_t	h2strings_min;
 	uint64_t	h2strings_max;
 	double		h2strings_avg;
+	size_t		h2klen_min;
+	size_t		h2klen_max;
+	double		h2klen_avg;
 };
 
 /*

src/tests/bench/bench_ph.c

@@ -335,6 +335,9 @@ main(int argc, char *argv[])
 	printf("%lu h2 min strings\n", stats.h2strings_min);
 	printf("%lu h2 max strings\n", stats.h2strings_max);
 	printf("%.1f h2 mean strings\n", stats.h2strings_avg);
+	printf("%lu h2 min key vector length\n", stats.h2klen_min);
+	printf("%lu h2 max key vector length\n", stats.h2klen_max);
+	printf("%.1f h2 mean key vector length\n", stats.h2klen_avg);
 
 	if (do_iters == 0)
 		exit(EXIT_SUCCESS);