1 files changed, 184 insertions, 0 deletions
diff --git a/t/helper/test-hashmap.c b/t/helper/test-hashmap.c
new file mode 100644
index 0000000000..16a3145c3a
--- /dev/null
+++ b/t/helper/test-hashmap.c
@@ -0,0 +1,184 @@
+#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(&parts, line.buf, DELIM, 2);
+		string_list_remove_empty_items(&parts, 0);
+
+		/* 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;
+}