From e031e9719d21c11102870b8037bdda995dede5e0 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ren=C3=A9=20Scharfe?= Date: Fri, 1 Oct 2021 11:12:27 +0200 Subject: [PATCH] test-mergesort: add test subcommand MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Adapt the qsort certification program from "Engineering a Sort Function" by Bentley and McIlroy for testing our linked list sort function. It generates several lists with various distribution patterns and counts the number of operations llist_mergesort() needs to order them. It compares the result to the output of a trusted sort function (qsort(1)) and also checks if the sort is stable. Also add a test script that makes use of the new subcommand. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano --- t/helper/test-mergesort.c | 232 +++++++++++++++++++++++++++++++++++++++++++++- t/t0071-sort.sh | 11 +++ 2 files changed, 242 insertions(+), 1 deletion(-) create mode 100755 t/t0071-sort.sh diff --git a/t/helper/test-mergesort.c b/t/helper/test-mergesort.c index 05be0d067a..8006be8bf8 100644 --- a/t/helper/test-mergesort.c +++ b/t/helper/test-mergesort.c @@ -50,9 +50,239 @@ static int sort_stdin(void) return 0; } +static void dist_sawtooth(int *arr, int n, int m) +{ + int i; + for (i = 0; i < n; i++) + arr[i] = i % m; +} + +static void dist_rand(int *arr, int n, int m) +{ + int i; + for (i = 0; i < n; i++) + arr[i] = rand() % m; +} + +static void dist_stagger(int *arr, int n, int m) +{ + int i; + for (i = 0; i < n; i++) + arr[i] = (i * m + i) % n; +} + +static void dist_plateau(int *arr, int n, int m) +{ + int i; + for (i = 0; i < n; i++) + arr[i] = (i < m) ? i : m; +} + +static void dist_shuffle(int *arr, int n, int m) +{ + int i, j, k; + for (i = j = 0, k = 1; i < n; i++) + arr[i] = (rand() % m) ? (j += 2) : (k += 2); +} + +#define DIST(name) { #name, dist_##name } + +static struct dist { + const char *name; + void (*fn)(int *arr, int n, int m); +} dist[] = { + DIST(sawtooth), + DIST(rand), + DIST(stagger), + DIST(plateau), + DIST(shuffle), +}; + +static void mode_copy(int *arr, int n) +{ + /* nothing */ +} + +static void mode_reverse(int *arr, int n) +{ + int i, j; + for (i = 0, j = n - 1; i < j; i++, j--) + SWAP(arr[i], arr[j]); +} + +static void mode_reverse_1st_half(int *arr, int n) +{ + mode_reverse(arr, n / 2); +} + +static void mode_reverse_2nd_half(int *arr, int n) +{ + int half = n / 2; + mode_reverse(arr + half, n - half); +} + +static int compare_ints(const void *av, const void *bv) +{ + const int *ap = av, *bp = bv; + int a = *ap, b = *bp; + return (a > b) - (a < b); +} + +static void mode_sort(int *arr, int n) +{ + QSORT(arr, n, compare_ints); +} + +static void mode_dither(int *arr, int n) +{ + int i; + for (i = 0; i < n; i++) + arr[i] += i % 5; +} + +#define MODE(name) { #name, mode_##name } + +static struct mode { + const char *name; + void (*fn)(int *arr, int n); +} mode[] = { + MODE(copy), + MODE(reverse), + MODE(reverse_1st_half), + MODE(reverse_2nd_half), + MODE(sort), + MODE(dither), +}; + +static struct stats { + int get_next, set_next, compare; +} stats; + +struct number { + int value, rank; + struct number *next; +}; + +static void *get_next_number(const void *a) +{ + stats.get_next++; + return ((const struct number *)a)->next; +} + +static void set_next_number(void *a, void *b) +{ + stats.set_next++; + ((struct number *)a)->next = b; +} + +static int compare_numbers(const void *av, const void *bv) +{ + const struct number *an = av, *bn = bv; + int a = an->value, b = bn->value; + stats.compare++; + return (a > b) - (a < b); +} + +static void clear_numbers(struct number *list) +{ + while (list) { + struct number *next = list->next; + free(list); + list = next; + } +} + +static int test(const struct dist *dist, const struct mode *mode, int n, int m) +{ + int *arr; + size_t i; + struct number *curr, *list, **tail; + int is_sorted = 1; + int is_stable = 1; + const char *verdict; + int result = -1; + + ALLOC_ARRAY(arr, n); + dist->fn(arr, n, m); + mode->fn(arr, n); + for (i = 0, tail = &list; i < n; i++) { + curr = xmalloc(sizeof(*curr)); + curr->value = arr[i]; + curr->rank = i; + *tail = curr; + tail = &curr->next; + } + *tail = NULL; + + stats.get_next = stats.set_next = stats.compare = 0; + list = llist_mergesort(list, get_next_number, set_next_number, + compare_numbers); + + QSORT(arr, n, compare_ints); + for (i = 0, curr = list; i < n && curr; i++, curr = curr->next) { + if (arr[i] != curr->value) + is_sorted = 0; + if (curr->next && curr->value == curr->next->value && + curr->rank >= curr->next->rank) + is_stable = 0; + } + if (i < n) { + verdict = "too short"; + } else if (curr) { + verdict = "too long"; + } else if (!is_sorted) { + verdict = "not sorted"; + } else if (!is_stable) { + verdict = "unstable"; + } else { + verdict = "OK"; + result = 0; + } + + printf("%-9s %-16s %8d %8d %8d %8d %8d %s\n", + dist->name, mode->name, n, m, stats.get_next, stats.set_next, + stats.compare, verdict); + + clear_numbers(list); + free(arr); + + return result; +} + +/* + * A version of the qsort certification program from "Engineering a Sort + * Function" by Bentley and McIlroy, Software—Practice and Experience, + * Volume 23, Issue 11, 1249–1265 (November 1993). + */ +static int run_tests(int argc, const char **argv) +{ + const char *argv_default[] = { "100", "1023", "1024", "1025" }; + if (!argc) + return run_tests(ARRAY_SIZE(argv_default), argv_default); + printf("%-9s %-16s %8s %8s %8s %8s %8s %s\n", + "distribut", "mode", "n", "m", "get_next", "set_next", + "compare", "verdict"); + while (argc--) { + int i, j, m, n = strtol(*argv++, NULL, 10); + for (i = 0; i < ARRAY_SIZE(dist); i++) { + for (j = 0; j < ARRAY_SIZE(mode); j++) { + for (m = 1; m < 2 * n; m *= 2) { + if (test(&dist[i], &mode[j], n, m)) + return 1; + } + } + } + } + return 0; +} + int cmd__mergesort(int argc, const char **argv) { if (argc == 2 && !strcmp(argv[1], "sort")) return sort_stdin(); - usage("test-tool mergesort sort"); + if (argc > 1 && !strcmp(argv[1], "test")) + return run_tests(argc - 2, argv + 2); + fprintf(stderr, "usage: test-tool mergesort sort\n"); + fprintf(stderr, " or: test-tool mergesort test [...]\n"); + return 129; } diff --git a/t/t0071-sort.sh b/t/t0071-sort.sh new file mode 100755 index 0000000000..a8ab174879 --- /dev/null +++ b/t/t0071-sort.sh @@ -0,0 +1,11 @@ +#!/bin/sh + +test_description='verify sort functions' + +. ./test-lib.sh + +test_expect_success 'llist_mergesort()' ' + test-tool mergesort test +' + +test_done -- 2.11.4.GIT