[PATCH 10/9 v2] test-mergesort: use repeatable random numbers
flat view
STALE1831d
From: René Scharfe <hidden>
Date: 2021-10-08 04:04:55
Subsystem:
the rest · Maintainer:
Linus Torvalds
Use MINSTD to generate pseudo-random numbers consistently instead of using rand(3), whose output can vary from system to system, and reset its seed before filling in the test values. This gives repeatable results across versions and systems, which simplifies sharing and comparing of results between developers. Signed-off-by: René Scharfe <redacted> --- Change: Use uint32_t to avoid relying on unsigned int being exactly 4 bytes wide. D'oh! t/helper/test-mergesort.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/t/helper/test-mergesort.c b/t/helper/test-mergesort.c
index 29758cf89b..c6fa816be3 100644
--- a/t/helper/test-mergesort.c
+++ b/t/helper/test-mergesort.c@@ -2,6 +2,12 @@ #include "cache.h" #include "mergesort.h" +static uint32_t minstd_rand(uint32_t *state) +{ + *state = (uint64_t)*state * 48271 % 2147483647; + return *state; +} + struct line { char *text; struct line *next;
@@ -60,8 +66,9 @@ static void dist_sawtooth(int *arr, int n, int m) static void dist_rand(int *arr, int n, int m) { int i; + uint32_t seed = 1; for (i = 0; i < n; i++) - arr[i] = rand() % m; + arr[i] = minstd_rand(&seed) % m; } static void dist_stagger(int *arr, int n, int m)
@@ -81,8 +88,9 @@ static void dist_plateau(int *arr, int n, int m) static void dist_shuffle(int *arr, int n, int m) { int i, j, k; + uint32_t seed = 1; for (i = j = 0, k = 1; i < n; i++) - arr[i] = (rand() % m) ? (j += 2) : (k += 2); + arr[i] = minstd_rand(&seed) % m ? (j += 2) : (k += 2); } #define DIST(name) { #name, dist_##name } --
2.33.0