[PATCH v2 1/8] packfile: use a `strmap` to store packs by name

From: Patrick Steinhardt <ps@pks.im>
Date: Oct 30, 2025, 10:38 UTC
Message-ID: <20251030-pks-packfiles-store-drop-list-v2-1-84654f080cc0@pks.im>
In-Reply-To: <20251030-pks-packfiles-store-drop-list-v2-0-84654f080cc0@pks.im>

To allow fast lookups of a packfile by name we use a hashmap that has the packfile name as key and the pack itself as value. But while this is the perfect use case for a `strmap`, we instead use `struct hashmap` and store the hashmap entry in the packfile itself.

Simplify the code by using a `strmap` instead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 packfile.c | 24 ++++--------------------
 packfile.h |  4 ++--
 2 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/packfile.c b/packfile.c
index 1ae2b2fe1ed..04649e52920 100644
--- a/packfile.c
+++ b/packfile.c
@@ -788,8 +788,7 @@ void packfile_store_add_pack(struct packfile_store *store,
 	pack->next = store->packs;
 	store->packs = pack;
 
-	hashmap_entry_init(&pack->packmap_ent, strhash(pack->pack_name));
-	hashmap_add(&store->map, &pack->packmap_ent);
+	strmap_put(&store->packs_by_path, pack->pack_name, pack);
 }
 
 struct packed_git *packfile_store_load_pack(struct packfile_store *store,
@@ -806,8 +805,7 @@ struct packed_git *packfile_store_load_pack(struct packfile_store *store,
 	strbuf_strip_suffix(&key, ".idx");
 	strbuf_addstr(&key, ".pack");
 
-	p = hashmap_get_entry_from_hash(&store->map, strhash(key.buf), key.buf,
-					struct packed_git, packmap_ent);
+	p = strmap_get(&store->packs_by_path, key.buf);
 	if (!p) {
 		p = add_packed_git(store->odb->repo, idx_path,
 				   strlen(idx_path), local);
@@ -2311,27 +2309,13 @@ int parse_pack_header_option(const char *in, unsigned char *out, unsigned int *l
 	return 0;
 }
 
-static int pack_map_entry_cmp(const void *cmp_data UNUSED,
-			      const struct hashmap_entry *entry,
-			      const struct hashmap_entry *entry2,
-			      const void *keydata)
-{
-	const char *key = keydata;
-	const struct packed_git *pg1, *pg2;
-
-	pg1 = container_of(entry, const struct packed_git, packmap_ent);
-	pg2 = container_of(entry2, const struct packed_git, packmap_ent);
-
-	return strcmp(pg1->pack_name, key ? key : pg2->pack_name);
-}
-
 struct packfile_store *packfile_store_new(struct object_database *odb)
 {
 	struct packfile_store *store;
 	CALLOC_ARRAY(store, 1);
 	store->odb = odb;
 	INIT_LIST_HEAD(&store->mru);
-	hashmap_init(&store->map, pack_map_entry_cmp, NULL, 0);
+	strmap_init(&store->packs_by_path);
 	return store;
 }
 
@@ -2341,7 +2325,7 @@ void packfile_store_free(struct packfile_store *store)
 		next = p->next;
 		free(p);
 	}
-	hashmap_clear(&store->map);
+	strmap_clear(&store->packs_by_path, 0);
 	free(store);
 }
 
diff --git a/packfile.h b/packfile.h
index c9d0b93446b..9da7f14317b 100644
--- a/packfile.h
+++ b/packfile.h
@@ -5,12 +5,12 @@
 #include "object.h"
 #include "odb.h"
 #include "oidset.h"
+#include "strmap.h"
 
 /* in odb.h */
 struct object_info;
 
 struct packed_git {
-	struct hashmap_entry packmap_ent;
 	struct packed_git *next;
 	struct list_head mru;
 	struct pack_window *windows;
@@ -85,7 +85,7 @@ struct packfile_store {
 	 * A map of packfile names to packed_git structs for tracking which
 	 * packs have been loaded already.
 	 */
-	struct hashmap map;
+	struct strmap packs_by_path;
 
 	/*
 	 * Whether packfiles have already been populated with this store's

-- 
2.51.2.997.g839fc31de9.dirty