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-rw-r--r--t/helper/test-mergesort.c405
1 files changed, 405 insertions, 0 deletions
diff --git a/t/helper/test-mergesort.c b/t/helper/test-mergesort.c
new file mode 100644
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--- /dev/null
+++ b/t/helper/test-mergesort.c
@@ -0,0 +1,405 @@
+#include "test-tool.h"
+#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;
+};
+
+DEFINE_LIST_SORT(static, sort_lines, struct line, next);
+
+static int compare_strings(const struct line *x, const struct line *y)
+{
+ return strcmp(x->text, y->text);
+}
+
+static int sort_stdin(void)
+{
+ struct line *lines;
+ struct line **tail = &lines;
+ struct strbuf sb = STRBUF_INIT;
+ struct mem_pool lines_pool;
+ char *p;
+
+ strbuf_read(&sb, 0, 0);
+
+ /*
+ * Split by newline, but don't create an item
+ * for the empty string after the last separator.
+ */
+ if (sb.len && sb.buf[sb.len - 1] == '\n')
+ strbuf_setlen(&sb, sb.len - 1);
+
+ mem_pool_init(&lines_pool, 0);
+ p = sb.buf;
+ for (;;) {
+ char *eol = strchr(p, '\n');
+ struct line *line = mem_pool_alloc(&lines_pool, sizeof(*line));
+ line->text = p;
+ *tail = line;
+ tail = &line->next;
+ if (!eol)
+ break;
+ *eol = '\0';
+ p = eol + 1;
+ }
+ *tail = NULL;
+
+ sort_lines(&lines, compare_strings);
+
+ while (lines) {
+ puts(lines->text);
+ lines = lines->next;
+ }
+ 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;
+ uint32_t seed = 1;
+ for (i = 0; i < n; i++)
+ arr[i] = minstd_rand(&seed) % 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;
+ uint32_t seed = 1;
+ for (i = j = 0, k = 1; i < n; i++)
+ arr[i] = minstd_rand(&seed) % 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 const struct dist *get_dist_by_name(const char *name)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(dist); i++) {
+ if (!strcmp(dist[i].name, name))
+ return &dist[i];
+ }
+ return NULL;
+}
+
+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;
+}
+
+static void unriffle(int *arr, int n, int *tmp)
+{
+ int i, j;
+ COPY_ARRAY(tmp, arr, n);
+ for (i = j = 0; i < n; i += 2)
+ arr[j++] = tmp[i];
+ for (i = 1; i < n; i += 2)
+ arr[j++] = tmp[i];
+}
+
+static void unriffle_recursively(int *arr, int n, int *tmp)
+{
+ if (n > 1) {
+ int half = n / 2;
+ unriffle(arr, n, tmp);
+ unriffle_recursively(arr, half, tmp);
+ unriffle_recursively(arr + half, n - half, tmp);
+ }
+}
+
+static void mode_unriffle(int *arr, int n)
+{
+ int *tmp;
+ ALLOC_ARRAY(tmp, n);
+ unriffle_recursively(arr, n, tmp);
+ free(tmp);
+}
+
+static unsigned int prev_pow2(unsigned int n)
+{
+ unsigned int pow2 = 1;
+ while (pow2 * 2 < n)
+ pow2 *= 2;
+ return pow2;
+}
+
+static void unriffle_recursively_skewed(int *arr, int n, int *tmp)
+{
+ if (n > 1) {
+ int pow2 = prev_pow2(n);
+ int rest = n - pow2;
+ unriffle(arr + pow2 - rest, rest * 2, tmp);
+ unriffle_recursively_skewed(arr, pow2, tmp);
+ unriffle_recursively_skewed(arr + pow2, rest, tmp);
+ }
+}
+
+static void mode_unriffle_skewed(int *arr, int n)
+{
+ int *tmp;
+ ALLOC_ARRAY(tmp, n);
+ unriffle_recursively_skewed(arr, n, tmp);
+ free(tmp);
+}
+
+#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),
+ MODE(unriffle),
+ MODE(unriffle_skewed),
+};
+
+static const struct mode *get_mode_by_name(const char *name)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(mode); i++) {
+ if (!strcmp(mode[i].name, name))
+ return &mode[i];
+ }
+ return NULL;
+}
+
+static int generate(int argc, const char **argv)
+{
+ const struct dist *dist = NULL;
+ const struct mode *mode = NULL;
+ int i, n, m, *arr;
+
+ if (argc != 4)
+ return 1;
+
+ dist = get_dist_by_name(argv[0]);
+ mode = get_mode_by_name(argv[1]);
+ n = strtol(argv[2], NULL, 10);
+ m = strtol(argv[3], NULL, 10);
+ if (!dist || !mode)
+ return 1;
+
+ ALLOC_ARRAY(arr, n);
+ dist->fn(arr, n, m);
+ mode->fn(arr, n);
+ for (i = 0; i < n; i++)
+ printf("%08x\n", arr[i]);
+ free(arr);
+ return 0;
+}
+
+static struct stats {
+ int get_next, set_next, compare;
+} stats;
+
+struct number {
+ int value, rank;
+ struct number *next;
+};
+
+DEFINE_LIST_SORT_DEBUG(static, sort_numbers, struct number, next,
+ stats.get_next++, stats.set_next++);
+
+static int compare_numbers(const struct number *an, const struct number *bn)
+{
+ 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;
+ sort_numbers(&list, 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)
+{
+ int i;
+ const char *sep;
+
+ if (argc == 6 && !strcmp(argv[1], "generate"))
+ return generate(argc - 2, argv + 2);
+ if (argc == 2 && !strcmp(argv[1], "sort"))
+ return sort_stdin();
+ if (argc > 1 && !strcmp(argv[1], "test"))
+ return run_tests(argc - 2, argv + 2);
+ fprintf(stderr, "usage: test-tool mergesort generate <distribution> <mode> <n> <m>\n");
+ fprintf(stderr, " or: test-tool mergesort sort\n");
+ fprintf(stderr, " or: test-tool mergesort test [<n>...]\n");
+ fprintf(stderr, "\n");
+ for (i = 0, sep = "distributions: "; i < ARRAY_SIZE(dist); i++, sep = ", ")
+ fprintf(stderr, "%s%s", sep, dist[i].name);
+ fprintf(stderr, "\n");
+ for (i = 0, sep = "modes: "; i < ARRAY_SIZE(mode); i++, sep = ", ")
+ fprintf(stderr, "%s%s", sep, mode[i].name);
+ fprintf(stderr, "\n");
+ return 129;
+}