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, 2 insertions, 3 deletions

diff --git a/name-hash.c b/name-hash.c
index 49fd508317..702cd0518f 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -213,12 +213,11 @@ struct cache_entry *index_dir_exists(struct index_state *istate, const char *nam
 struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
 {
 	struct cache_entry *ce;
-	struct hashmap_entry key;
 
 	lazy_init_name_hash(istate);
 
-	hashmap_entry_init(&key, memihash(name, namelen));
-	ce = hashmap_get(&istate->name_hash, &key, NULL);
+	ce = hashmap_get_from_hash(&istate->name_hash,
+				   memihash(name, namelen), NULL);
 	while (ce) {
 		if (same_name(ce, name, namelen, icase))
 			return ce;