oidmap: map with OID as key

This is similar to using the hashmap in hashmap.c, but with an
easier-to-use API. In particular, custom entry comparisons no longer
need to be written, and lookups can be done without constructing a
temporary entry structure.

This is implemented as a thin wrapper over the hashmap API. In
particular, this means that there is an additional 4-byte overhead due
to the fact that the first 4 bytes of the hash is redundantly stored.
For now, I'm taking the simpler approach, but if need be, we can
reimplement oidmap without affecting the callers significantly.

oidset has been updated to use oidmap.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 28 deletions

diff --git a/oidset.c b/oidset.c
index a6a08ba52a..f1f874aaad 100644
--- a/oidset.c
+++ b/oidset.c
@@ -1,50 +1,30 @@
 #include "cache.h"
 #include "oidset.h"
 
-struct oidset_entry {
-	struct hashmap_entry hash;
-	struct object_id oid;
-};
-
-static int oidset_hashcmp(const void *unused_cmp_data,
-			  const void *va, const void *vb,
-			  const void *vkey)
-{
-	const struct oidset_entry *a = va, *b = vb;
-	const struct object_id *key = vkey;
-	return oidcmp(&a->oid, key ? key : &b->oid);
-}
-
 int oidset_contains(const struct oidset *set, const struct object_id *oid)
 {
-	struct hashmap_entry key;
-
-	if (!set->map.cmpfn)
+	if (!set->map.map.tablesize)
 		return 0;
-
-	hashmap_entry_init(&key, sha1hash(oid->hash));
-	return !!hashmap_get(&set->map, &key, oid);
+	return !!oidmap_get(&set->map, oid);
 }
 
 int oidset_insert(struct oidset *set, const struct object_id *oid)
 {
-	struct oidset_entry *entry;
-
-	if (!set->map.cmpfn)
-		hashmap_init(&set->map, oidset_hashcmp, NULL, 0);
+	struct oidmap_entry *entry;
 
-	if (oidset_contains(set, oid))
+	if (!set->map.map.tablesize)
+		oidmap_init(&set->map, 0);
+	else if (oidset_contains(set, oid))
 		return 1;
 
 	entry = xmalloc(sizeof(*entry));
-	hashmap_entry_init(&entry->hash, sha1hash(oid->hash));
 	oidcpy(&entry->oid, oid);
 
-	hashmap_add(&set->map, entry);
+	oidmap_put(&set->map, entry);
 	return 0;
 }
 
 void oidset_clear(struct oidset *set)
 {
-	hashmap_free(&set->map, 1);
+	oidmap_free(&set->map, 1);
 }