lib/ccan/htable: benchmark against hsearch(3)

Since that has a fixed hash table size and doesn't support delete, we can't
do a thorough comparison, but we can insert and search.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(Imported from CCAN commit 95757f0e9d979e7c653e9b53bb640deb4f0ea1f9)

1 files changed, 103 insertions, 0 deletions

diff --git a/lib/ccan/htable/tools/hsearchspeed.c b/lib/ccan/htable/tools/hsearchspeed.c
new file mode 100644
index 0000000000..ea1a3f5c4e
--- /dev/null
+++ b/lib/ccan/htable/tools/hsearchspeed.c
@@ -0,0 +1,103 @@
+/* Simple speed tests for a hash of strings using hsearch */
+#include <ccan/htable/htable_type.h>
+#include <ccan/htable/htable.c>
+#include <ccan/str_talloc/str_talloc.h>
+#include <ccan/grab_file/grab_file.h>
+#include <ccan/talloc/talloc.h>
+#include <ccan/hash/hash.h>
+#include <ccan/time/time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <search.h>
+
+/* Nanoseconds per operation */
+static size_t normalize(const struct timeval *start,
+			const struct timeval *stop,
+			unsigned int num)
+{
+	struct timeval diff;
+
+	timersub(stop, start, &diff);
+
+	/* Floating point is more accurate here. */
+	return (double)(diff.tv_sec * 1000000 + diff.tv_usec)
+		/ num * 1000;
+}
+
+int main(int argc, char *argv[])
+{
+	size_t i, j, num;
+	struct timeval start, stop;
+	char **w;
+	ENTRY *words, *misswords;
+
+	w = strsplit(NULL, grab_file(NULL,
+				     argv[1] ? argv[1] : "/usr/share/dict/words",
+				     NULL), "\n");
+	num = talloc_array_length(w) - 1;
+	printf("%zu words\n", num);
+
+	hcreate(num+num/3);
+
+	words = talloc_array(w, ENTRY, num);
+	for (i = 0; i < num; i++) {
+		words[i].key = w[i];
+		words[i].data = words[i].key;
+	}
+
+	/* Append and prepend last char for miss testing. */
+	misswords = talloc_array(w, ENTRY, num);
+	for (i = 0; i < num; i++) {
+		char lastc;
+		if (strlen(w[i]))
+			lastc = w[i][strlen(w[i])-1];
+		else
+			lastc = 'z';
+		misswords[i].key = talloc_asprintf(misswords, "%c%s%c%c",
+						   lastc, w[i],
+						   lastc, lastc);
+	}
+
+	printf("#01: Initial insert: ");
+	fflush(stdout);
+	start = time_now();
+	for (i = 0; i < num; i++)
+		hsearch(words[i], ENTER);
+	stop = time_now();
+	printf(" %zu ns\n", normalize(&start, &stop, num));
+
+	printf("#02: Initial lookup (match): ");
+	fflush(stdout);
+	start = time_now();
+	for (i = 0; i < num; i++)
+		if (hsearch(words[i], FIND)->data != words[i].data)
+			abort();
+	stop = time_now();
+	printf(" %zu ns\n", normalize(&start, &stop, num));
+
+	printf("#03: Initial lookup (miss): ");
+	fflush(stdout);
+	start = time_now();
+	for (i = 0; i < num; i++) {
+		if (hsearch(misswords[i], FIND))
+			abort();
+	}
+	stop = time_now();
+	printf(" %zu ns\n", normalize(&start, &stop, num));
+
+	/* Lookups in order are very cache-friendly for judy; try random */
+	printf("#04: Initial lookup (random): ");
+	fflush(stdout);
+	start = time_now();
+	for (i = 0, j = 0; i < num; i++, j = (j + 10007) % num)
+		if (hsearch(words[i], FIND)->data != words[i].data)
+			abort();
+	stop = time_now();
+	printf(" %zu ns\n", normalize(&start, &stop, num));
+
+	return 0;
+}