[PATCH 6/9] pack-bitmap: expose function to iterate over bitmapped objects

[Patrick Steinhardt <ps@pks.im>]

Expose a function that allows the caller to iterate over all bitmapped
objects of a specific type. This mechanism allows us to use the object
type-specific bitmaps to enumerate all objects of that type without
having to scan through a complete packfile.

This functionality will be used in a subsequent commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/pack-objects.c |  3 ++-
 builtin/rev-list.c     |  3 ++-
 pack-bitmap.c          | 65 +++++++++++++++++++++++++++++++-------------------
 pack-bitmap.h          | 12 +++++++++-
 reachable.c            |  3 ++-
 5 files changed, 57 insertions(+), 29 deletions(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 58a9b161262..8f99e2b4fa8 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1735,7 +1735,8 @@ static int add_object_entry(const struct object_id *oid, enum object_type type,
 static int add_object_entry_from_bitmap(const struct object_id *oid,
 					enum object_type type,
 					int flags UNUSED, uint32_t name_hash,
-					struct packed_git *pack, off_t offset)
+					struct packed_git *pack, off_t offset,
+					void *payload UNUSED)
 {
 	display_progress(progress_state, ++nr_seen);
 
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index bb26bee0d45..1100dd2abe7 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -429,7 +429,8 @@ static int show_object_fast(
 	int exclude UNUSED,
 	uint32_t name_hash UNUSED,
 	struct packed_git *found_pack UNUSED,
-	off_t found_offset UNUSED)
+	off_t found_offset UNUSED,
+	void *payload UNUSED)
 {
 	fprintf(stdout, "%s\n", oid_to_hex(oid));
 	return 1;
diff --git a/pack-bitmap.c b/pack-bitmap.c
index 6406953d322..fc92e0aae65 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -1509,50 +1509,45 @@ static void show_extended_objects(struct bitmap_index *bitmap_git,
 		    (obj->type == OBJ_TAG && !revs->tag_objects))
 			continue;
 
-		show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
+		show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0, NULL);
 	}
 }
 
-static void init_type_iterator(struct ewah_iterator *it,
-			       struct bitmap_index *bitmap_git,
-			       enum object_type type)
+static struct ewah_bitmap *ewah_for_type(struct bitmap_index *bitmap_git,
+					 enum object_type type)
 {
 	switch (type) {
 	case OBJ_COMMIT:
-		ewah_iterator_init(it, bitmap_git->commits);
-		break;
-
+		return bitmap_git->commits;
 	case OBJ_TREE:
-		ewah_iterator_init(it, bitmap_git->trees);
-		break;
-
+		return bitmap_git->trees;
 	case OBJ_BLOB:
-		ewah_iterator_init(it, bitmap_git->blobs);
-		break;
-
+		return bitmap_git->blobs;
 	case OBJ_TAG:
-		ewah_iterator_init(it, bitmap_git->tags);
-		break;
-
+		return bitmap_git->tags;
 	default:
 		BUG("object type %d not stored by bitmap type index", type);
-		break;
 	}
 }
 
-static void show_objects_for_type(
-	struct bitmap_index *bitmap_git,
-	enum object_type object_type,
-	show_reachable_fn show_reach)
+static void init_type_iterator(struct ewah_iterator *it,
+			       struct bitmap_index *bitmap_git,
+			       enum object_type type)
+{
+	ewah_iterator_init(it, ewah_for_type(bitmap_git, type));
+}
+
+static void for_each_bitmapped_object_internal(struct bitmap_index *bitmap_git,
+					       struct bitmap *objects,
+					       enum object_type object_type,
+					       show_reachable_fn show_reach,
+					       void *payload)
 {
 	size_t i = 0;
 	uint32_t offset;
-
 	struct ewah_iterator it;
 	eword_t filter;
 
-	struct bitmap *objects = bitmap_git->result;
-
 	init_type_iterator(&it, bitmap_git, object_type);
 
 	for (i = 0; i < objects->word_alloc &&
@@ -1595,11 +1590,31 @@ static void show_objects_for_type(
 			if (bitmap_git->hashes)
 				hash = get_be32(bitmap_git->hashes + index_pos);
 
-			show_reach(&oid, object_type, 0, hash, pack, ofs);
+			show_reach(&oid, object_type, 0, hash, pack, ofs, payload);
 		}
 	}
 }
 
+static void show_objects_for_type(
+	struct bitmap_index *bitmap_git,
+	enum object_type object_type,
+	show_reachable_fn show_reach)
+{
+	for_each_bitmapped_object_internal(bitmap_git, bitmap_git->result,
+					   object_type, show_reach, NULL);
+}
+
+void for_each_bitmapped_object(struct bitmap_index *bitmap_git,
+			       enum object_type object_type,
+			       show_reachable_fn show_reach,
+			       void *payload)
+{
+	struct bitmap *bitmap = ewah_to_bitmap(ewah_for_type(bitmap_git, object_type));
+	for_each_bitmapped_object_internal(bitmap_git, bitmap,
+					   object_type, show_reach, payload);
+	bitmap_free(bitmap);
+}
+
 static int in_bitmapped_pack(struct bitmap_index *bitmap_git,
 			     struct object_list *roots)
 {
diff --git a/pack-bitmap.h b/pack-bitmap.h
index d7f4b8b8e95..3368e79ed5a 100644
--- a/pack-bitmap.h
+++ b/pack-bitmap.h
@@ -50,7 +50,8 @@ typedef int (*show_reachable_fn)(
 	int flags,
 	uint32_t hash,
 	struct packed_git *found_pack,
-	off_t found_offset);
+	off_t found_offset,
+	void *payload);
 
 struct bitmap_index;
 
@@ -78,6 +79,15 @@ int test_bitmap_pseudo_merges(struct repository *r);
 int test_bitmap_pseudo_merge_commits(struct repository *r, uint32_t n);
 int test_bitmap_pseudo_merge_objects(struct repository *r, uint32_t n);
 
+/*
+ * Iterate through all bitmapped objects of the given type and execute the
+ * `show_reach` for each of them.
+ */
+ void for_each_bitmapped_object(struct bitmap_index *bitmap_git,
+			       enum object_type object_type,
+			       show_reachable_fn show_reach,
+			       void *payload);
+
 #define GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL \
 	"GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL"
 
diff --git a/reachable.c b/reachable.c
index ecf7ccf5041..dd33c7f07dd 100644
--- a/reachable.c
+++ b/reachable.c
@@ -337,7 +337,8 @@ static int mark_object_seen(const struct object_id *oid,
 			     int exclude UNUSED,
 			     uint32_t name_hash UNUSED,
 			     struct packed_git *found_pack UNUSED,
-			     off_t found_offset UNUSED)
+			     off_t found_offset UNUSED,
+			     void *payload UNUSED)
 {
 	struct object *obj = lookup_object_by_type(the_repository, oid, type);
 	if (!obj)

-- 
2.48.1.683.gf705b3209c.dirty