t/helper/test-hashmap.c

#include "test-tool.h"
#include "git-compat-util.h"
#include "hashmap.h"
#include "strbuf.h"
#include "string-list.h"

struct test_entry
{
	int padding; /* hashmap entry no longer needs to be the first member */
	struct hashmap_entry ent;
	/* key and value as two \0-terminated strings */
	char key[FLEX_ARRAY];
};

static int test_entry_cmp(const void *cmp_data,
			  const struct hashmap_entry *eptr,
			  const struct hashmap_entry *entry_or_key,
			  const void *keydata)
{
	const int ignore_case = cmp_data ? *((int *)cmp_data) : 0;
	const struct test_entry *e1, *e2;
	const char *key = keydata;

	e1 = container_of(eptr, const struct test_entry, ent);
	e2 = container_of(entry_or_key, const struct test_entry, ent);

	if (ignore_case)
		return strcasecmp(e1->key, key ? key : e2->key);
	else
		return strcmp(e1->key, key ? key : e2->key);
}

static struct test_entry *alloc_test_entry(unsigned int hash,
					   const char *key,
					   const char *value)
{
	size_t klen = strlen(key);
	size_t vlen = strlen(value);
	struct test_entry *entry = xmalloc(st_add4(sizeof(*entry), klen, vlen, 2));
	hashmap_entry_init(&entry->ent, hash);
	memcpy(entry->key, key, klen + 1);
	memcpy(entry->key + klen + 1, value, vlen + 1);
	return entry;
}

#define HASH_METHOD_FNV 0
#define HASH_METHOD_I 1
#define HASH_METHOD_IDIV10 2
#define HASH_METHOD_0 3
#define HASH_METHOD_X2 4
#define TEST_SPARSE 8
#define TEST_ADD 16
#define TEST_SIZE 100000

static unsigned int hash(unsigned int method, unsigned int i, const char *key)
{
	unsigned int hash = 0;
	switch (method & 3)
	{
	case HASH_METHOD_FNV:
		hash = strhash(key);
		break;
	case HASH_METHOD_I:
		hash = i;
		break;
	case HASH_METHOD_IDIV10:
		hash = i / 10;
		break;
	case HASH_METHOD_0:
		hash = 0;
		break;
	}

	if (method & HASH_METHOD_X2)
		hash = 2 * hash;
	return hash;
}

/*
 * Test performance of hashmap.[ch]
 * Usage: time echo "perfhashmap method rounds" | test-tool hashmap
 */
static void perf_hashmap(unsigned int method, unsigned int rounds)
{
	struct hashmap map;
	char buf[16];
	struct test_entry **entries;
	unsigned int *hashes;
	unsigned int i, j;

	ALLOC_ARRAY(entries, TEST_SIZE);
	ALLOC_ARRAY(hashes, TEST_SIZE);
	for (i = 0; i < TEST_SIZE; i++) {
		xsnprintf(buf, sizeof(buf), "%i", i);
		entries[i] = alloc_test_entry(0, buf, "");
		hashes[i] = hash(method, i, entries[i]->key);
	}

	if (method & TEST_ADD) {
		/* test adding to the map */
		for (j = 0; j < rounds; j++) {
			hashmap_init(&map, test_entry_cmp, NULL, 0);

			/* add entries */
			for (i = 0; i < TEST_SIZE; i++) {
				hashmap_entry_init(&entries[i]->ent, hashes[i]);
				hashmap_add(&map, &entries[i]->ent);
			}

			hashmap_clear(&map);
		}
	} else {
		/* test map lookups */
		hashmap_init(&map, test_entry_cmp, NULL, 0);

		/* fill the map (sparsely if specified) */
		j = (method & TEST_SPARSE) ? TEST_SIZE / 10 : TEST_SIZE;
		for (i = 0; i < j; i++) {
			hashmap_entry_init(&entries[i]->ent, hashes[i]);
			hashmap_add(&map, &entries[i]->ent);
		}

		for (j = 0; j < rounds; j++) {
			for (i = 0; i < TEST_SIZE; i++) {
				hashmap_get_from_hash(&map, hashes[i],
						      entries[i]->key);
			}
		}

		hashmap_clear(&map);
	}
}

#define DELIM " \t\r\n"

/*
 * Read stdin line by line and print result of commands to stdout:
 *
 * perfhashmap method rounds -> test hashmap.[ch] performance
 *
 * NOTE: this is not used by any of our mechanized build & test
 * procedure, after 3469a236 (t: port helper/test-hashmap.c to
 * unit-tests/t-hashmap.c, 2024-08-03).  See the log message of that
 * commit for the reason why this is still here.
 */
int cmd__hashmap(int argc UNUSED, const char **argv UNUSED)
{
	struct string_list parts = STRING_LIST_INIT_NODUP;
	struct strbuf line = STRBUF_INIT;

	/* process commands from stdin */
	while (strbuf_getline(&line, stdin) != EOF) {
		char *cmd, *p1, *p2;

		/* break line into command and up to two parameters */
		string_list_setlen(&parts, 0);
		string_list_split_in_place_f(&parts, line.buf, DELIM, 2,
					     STRING_LIST_SPLIT_NONEMPTY);

		/* ignore empty lines */
		if (!parts.nr)
			continue;
		if (!*parts.items[0].string || *parts.items[0].string == '#')
			continue;

		cmd = parts.items[0].string;
		p1 = parts.nr >= 1 ? parts.items[1].string : NULL;
		p2 = parts.nr >= 2 ? parts.items[2].string : NULL;

		if (!strcmp("perfhashmap", cmd) && p1 && p2) {

			perf_hashmap(atoi(p1), atoi(p2));

		} else {

			printf("Unknown command %s\n", cmd);

		}
	}

	string_list_clear(&parts, 0);
	strbuf_release(&line);
	return 0;
}