Merge branch 'ps/receive-pack-shallow-optim' into jch

The code to accept shallow "git push" has been optimized.

* ps/receive-pack-shallow-optim:
  commit: use commit graph in `lookup_commit_reference_gently()`
  commit: make `repo_parse_commit_no_graph()` more robust
  commit: avoid parsing non-commits in `lookup_commit_reference_gently()`

commit.c

@@ -42,13 +42,35 @@ const char *commit_type = "commit";
 struct commit *lookup_commit_reference_gently(struct repository *r,
 		const struct object_id *oid, int quiet)
 {
-	struct object *obj = deref_tag(r,
-				       parse_object(r, oid),
-				       NULL, 0);
+	const struct object_id *maybe_peeled;
+	struct object_id peeled_oid;
+	struct commit *commit;
+	enum object_type type;
 
-	if (!obj)
+	switch (peel_object_ext(r, oid, &peeled_oid, 0, &type)) {
+	case PEEL_NON_TAG:
+		maybe_peeled = oid;
+		break;
+	case PEEL_PEELED:
+		maybe_peeled = &peeled_oid;
+		break;
+	default:
 		return NULL;
-	return object_as_type(obj, OBJ_COMMIT, quiet);
+	}
+
+	if (type != OBJ_COMMIT) {
+		if (!quiet)
+			error(_("object %s is a %s, not a %s"),
+			      oid_to_hex(oid), type_name(type),
+			      type_name(OBJ_COMMIT));
+		return NULL;
+	}
+
+	commit = lookup_commit(r, maybe_peeled);
+	if (!commit || repo_parse_commit_gently(r, commit, quiet) < 0)
+		return NULL;
+
+	return commit;
 }
 
 struct commit *lookup_commit_reference(struct repository *r, const struct object_id *oid)

commit.h

@@ -103,16 +103,26 @@ static inline int repo_parse_commit(struct repository *r, struct commit *item)
 	return repo_parse_commit_gently(r, item, 0);
 }
 
+void unparse_commit(struct repository *r, const struct object_id *oid);
+
 static inline int repo_parse_commit_no_graph(struct repository *r,
 					     struct commit *commit)
 {
+	/*
+	 * When the commit has been parsed but its tree wasn't populated then
+	 * this is an indicator that it has been parsed via the commit-graph.
+	 * We cannot read the tree via the commit-graph, as we're explicitly
+	 * told not to use it. We thus have to first un-parse the object so
+	 * that we can re-parse it without the graph.
+	 */
+	if (commit->object.parsed && !commit->maybe_tree)
+		unparse_commit(r, &commit->object.oid);
+
 	return repo_parse_commit_internal(r, commit, 0, 0);
 }
 
 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);

contrib/coccinelle/commit.cocci

@@ -26,7 +26,7 @@ expression s;
 // repo_get_commit_tree() on the LHS.
 @@
 identifier f != { repo_get_commit_tree, get_commit_tree_in_graph_one,
-		  load_tree_for_commit, set_commit_tree };
+		  load_tree_for_commit, set_commit_tree, repo_parse_commit_no_graph };
 expression c;
 @@
   f(...) {<...

object.c

@@ -207,10 +207,11 @@ struct object *lookup_object_by_type(struct repository *r,
 	}
 }
 
-enum peel_status peel_object(struct repository *r,
-			     const struct object_id *name,
-			     struct object_id *oid,
-			     unsigned flags)
+enum peel_status peel_object_ext(struct repository *r,
+				 const struct object_id *name,
+				 struct object_id *oid,
+				 unsigned flags,
+				 enum object_type *typep)
 {
 	struct object *o = lookup_unknown_object(r, name);
 
@@ -220,8 +221,10 @@ enum peel_status peel_object(struct repository *r,
 			return PEEL_INVALID;
 	}
 
-	if (o->type != OBJ_TAG)
+	if (o->type != OBJ_TAG) {
+		*typep = o->type;
 		return PEEL_NON_TAG;
+	}
 
 	while (o && o->type == OBJ_TAG) {
 		o = parse_object(r, &o->oid);
@@ -241,9 +244,19 @@ enum peel_status peel_object(struct repository *r,
 		return PEEL_INVALID;
 
 	oidcpy(oid, &o->oid);
+	*typep = o->type;
 	return PEEL_PEELED;
 }
 
+enum peel_status peel_object(struct repository *r,
+			     const struct object_id *name,
+			     struct object_id *oid,
+			     unsigned flags)
+{
+	enum object_type dummy;
+	return peel_object_ext(r, name, oid, flags, &dummy);
+}
+
 struct object *parse_object_buffer(struct repository *r, const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
 {
 	struct object *obj;

object.h

@@ -309,6 +309,11 @@ enum peel_status peel_object(struct repository *r,
 			     const struct object_id *name,
 			     struct object_id *oid,
 			     unsigned flags);
+enum peel_status peel_object_ext(struct repository *r,
+				 const struct object_id *name,
+				 struct object_id *oid,
+				 unsigned flags,
+				 enum object_type *typep);
 
 struct object_list *object_list_insert(struct object *item,
 				       struct object_list **list_p);