object: clear grafts when clearing parsed object pool

We do not clear grafts part of the parsed object pool when clearing the
pool itself, which can lead to memory leaks when a repository is being
cleared.

Fix this by moving `reset_commit_grafts()` into "object.c" and making it
part of the `struct parsed_object_pool` interface such that we can call
it from `parsed_object_pool_clear()`. Adapt `parsed_object_pool_new()`
to take and store a reference to its owning repository, which is needed
by `unparse_commit()`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -177,7 +177,7 @@ int commit_graft_pos(struct repository *r, const struct object_id *oid)
 		       commit_graft_oid_access);
 }
 
-static void unparse_commit(struct repository *r, const struct object_id *oid)
+void unparse_commit(struct repository *r, const struct object_id *oid)
 {
 	struct commit *c = lookup_commit(r, oid);
 
@@ -318,18 +318,6 @@ int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 	return ret;
 }
 
-void reset_commit_grafts(struct repository *r)
-{
-	int i;
-
-	for (i = 0; i < r->parsed_objects->grafts_nr; i++) {
-		unparse_commit(r, &r->parsed_objects->grafts[i]->oid);
-		free(r->parsed_objects->grafts[i]);
-	}
-	r->parsed_objects->grafts_nr = 0;
-	r->parsed_objects->commit_graft_prepared = 0;
-}
-
 struct commit_buffer {
 	void *buffer;
 	unsigned long size;

commit.h

@@ -108,6 +108,8 @@ static inline int repo_parse_commit_no_graph(struct repository *r,
 
 void parse_commit_or_die(struct commit *item);
 
+void unparse_commit(struct repository *r, const struct object_id *oid);
+
 struct buffer_slab;
 struct buffer_slab *allocate_commit_buffer_slab(void);
 void free_commit_buffer_slab(struct buffer_slab *bs);
@@ -240,7 +242,6 @@ int commit_graft_pos(struct repository *r, const struct object_id *oid);
 int register_commit_graft(struct repository *r, struct commit_graft *, int);
 void prepare_commit_graft(struct repository *r);
 struct commit_graft *lookup_commit_graft(struct repository *r, const struct object_id *oid);
-void reset_commit_grafts(struct repository *r);
 
 struct commit *get_fork_point(const char *refname, struct commit *commit);
 

object.c

@@ -545,11 +545,12 @@ void repo_clear_commit_marks(struct repository *r, unsigned int flags)
 	}
 }
 
-struct parsed_object_pool *parsed_object_pool_new(void)
+struct parsed_object_pool *parsed_object_pool_new(struct repository *repo)
 {
 	struct parsed_object_pool *o = xmalloc(sizeof(*o));
 	memset(o, 0, sizeof(*o));
 
+	o->repo = repo;
 	o->blob_state = allocate_alloc_state();
 	o->tree_state = allocate_alloc_state();
 	o->commit_state = allocate_alloc_state();
@@ -628,6 +629,16 @@ void raw_object_store_clear(struct raw_object_store *o)
 	hashmap_clear(&o->pack_map);
 }
 
+void parsed_object_pool_reset_commit_grafts(struct parsed_object_pool *o)
+{
+	for (int i = 0; i < o->grafts_nr; i++) {
+		unparse_commit(o->repo, &o->grafts[i]->oid);
+		free(o->grafts[i]);
+	}
+	o->grafts_nr = 0;
+	o->commit_graft_prepared = 0;
+}
+
 void parsed_object_pool_clear(struct parsed_object_pool *o)
 {
 	/*
@@ -659,6 +670,7 @@ void parsed_object_pool_clear(struct parsed_object_pool *o)
 	free_commit_buffer_slab(o->buffer_slab);
 	o->buffer_slab = NULL;
 
+	parsed_object_pool_reset_commit_grafts(o);
 	clear_alloc_state(o->blob_state);
 	clear_alloc_state(o->tree_state);
 	clear_alloc_state(o->commit_state);

object.h

@@ -7,6 +7,7 @@ struct buffer_slab;
 struct repository;
 
 struct parsed_object_pool {
+	struct repository *repo;
 	struct object **obj_hash;
 	int nr_objs, obj_hash_size;
 
@@ -31,8 +32,9 @@ struct parsed_object_pool {
 	struct buffer_slab *buffer_slab;
 };
 
-struct parsed_object_pool *parsed_object_pool_new(void);
+struct parsed_object_pool *parsed_object_pool_new(struct repository *repo);
 void parsed_object_pool_clear(struct parsed_object_pool *o);
+void parsed_object_pool_reset_commit_grafts(struct parsed_object_pool *o);
 
 struct object_list {
 	struct object *item;

repository.c

@@ -54,7 +54,7 @@ void initialize_repository(struct repository *repo)
 {
 	repo->objects = raw_object_store_new();
 	repo->remote_state = remote_state_new();
-	repo->parsed_objects = parsed_object_pool_new();
+	repo->parsed_objects = parsed_object_pool_new(repo);
 	ALLOC_ARRAY(repo->index, 1);
 	index_state_init(repo->index, repo);
 

shallow.c

@@ -97,7 +97,7 @@ static void reset_repository_shallow(struct repository *r)
 {
 	r->parsed_objects->is_shallow = -1;
 	stat_validity_clear(r->parsed_objects->shallow_stat);
-	reset_commit_grafts(r);
+	parsed_object_pool_reset_commit_grafts(r->parsed_objects);
 }
 
 int commit_shallow_file(struct repository *r, struct shallow_lock *lk)