hashmap: add simplified hashmap_get_from_hash() API

Hashmap entries are typically looked up by just a key. The hashmap_get()
API expects an initialized entry structure instead, to support compound
keys. This flexibility is currently only needed by find_dir_entry() in
name-hash.c (and compat/win32/fscache.c in the msysgit fork). All other
(currently five) call sites of hashmap_get() have to set up a near emtpy
entry structure, resulting in duplicate code like this:

  struct hashmap_entry keyentry;
  hashmap_entry_init(&keyentry, hash(key));
  return hashmap_get(map, &keyentry, key);

Add a hashmap_get_from_hash() API that allows hashmap lookups by just
specifying the key and its hash code, i.e.:

  return hashmap_get_from_hash(map, hash(key), key);

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 8 deletions

diff --git a/test-hashmap.c b/test-hashmap.c
index f5183fb9e8..3c9f67bcb2 100644
--- a/test-hashmap.c
+++ b/test-hashmap.c
@@ -115,9 +115,8 @@ static void perf_hashmap(unsigned int method, unsigned int rounds)
 
 		for (j = 0; j < rounds; j++) {
 			for (i = 0; i < TEST_SIZE; i++) {
-				struct hashmap_entry key;
-				hashmap_entry_init(&key, hashes[i]);
-				hashmap_get(&map, &key, entries[i]->key);
+				hashmap_get_from_hash(&map, hashes[i],
+						      entries[i]->key);
 			}
 		}
 
@@ -199,12 +198,8 @@ int main(int argc, char *argv[])
 
 		} else if (!strcmp("get", cmd) && l1) {
 
-			/* setup static key */
-			struct hashmap_entry key;
-			hashmap_entry_init(&key, hash);
-
 			/* lookup entry in hashmap */
-			entry = hashmap_get(&map, &key, p1);
+			entry = hashmap_get_from_hash(&map, hash, p1);
 
 			/* print result */
 			if (!entry)