merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/oidmap.c

@@ -0,0 +1,55 @@
+#include "cache.h"
+#include "oidmap.h"
+
+static int oidmap_neq(const void *hashmap_cmp_fn_data,
+		      const void *entry, const void *entry_or_key,
+		      const void *keydata)
+{
+	const struct oidmap_entry *entry_ = entry;
+	if (keydata)
+		return !oideq(&entry_->oid, (const struct object_id *) keydata);
+	return !oideq(&entry_->oid,
+		      &((const struct oidmap_entry *) entry_or_key)->oid);
+}
+
+void oidmap_init(struct oidmap *map, size_t initial_size)
+{
+	hashmap_init(&map->map, oidmap_neq, NULL, initial_size);
+}
+
+void oidmap_free(struct oidmap *map, int free_entries)
+{
+	if (!map)
+		return;
+	hashmap_free(&map->map, free_entries);
+}
+
+void *oidmap_get(const struct oidmap *map, const struct object_id *key)
+{
+	if (!map->map.cmpfn)
+		return NULL;
+
+	return hashmap_get_from_hash(&map->map, oidhash(key), key);
+}
+
+void *oidmap_remove(struct oidmap *map, const struct object_id *key)
+{
+	struct hashmap_entry entry;
+
+	if (!map->map.cmpfn)
+		oidmap_init(map, 0);
+
+	hashmap_entry_init(&entry, oidhash(key));
+	return hashmap_remove(&map->map, &entry, key);
+}
+
+void *oidmap_put(struct oidmap *map, void *entry)
+{
+	struct oidmap_entry *to_put = entry;
+
+	if (!map->map.cmpfn)
+		oidmap_init(map, 0);
+
+	hashmap_entry_init(&to_put->internal_entry, oidhash(&to_put->oid));
+	return hashmap_put(&map->map, to_put);
+}