treewide: rename tree to maybe_tree

Using the commit-graph file to walk commit history removes the large
cost of parsing commits during the walk. This exposes a performance
issue: lookup_tree() takes a large portion of the computation time,
even when Git never uses those trees.

In anticipation of lazy-loading these trees, rename the 'tree' member
of struct commit to 'maybe_tree'. This serves two purposes: it hints
at the future role of possibly being NULL even if the commit has a
valid tree, and it allows for unambiguous transformation from simple
member access (i.e. commit->maybe_tree) to method access.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fsck.c b/fsck.c
index 5c8c12dde3..3228ca5bee 100644
--- a/fsck.c
+++ b/fsck.c
@@ -396,9 +396,9 @@ static int fsck_walk_commit(struct commit *commit, void *data, struct fsck_optio
 
 	name = get_object_name(options, &commit->object);
 	if (name)
-		put_object_name(options, &commit->tree->object, "%s:", name);
+		put_object_name(options, &commit->maybe_tree->object, "%s:", name);
 
-	result = options->walk((struct object *)commit->tree, OBJ_TREE, data, options);
+	result = options->walk((struct object *)commit->maybe_tree, OBJ_TREE, data, options);
 	if (result < 0)
 		return result;
 	res = result;
@@ -772,7 +772,7 @@ static int fsck_commit_buffer(struct commit *commit, const char *buffer,
 	err = fsck_ident(&buffer, &commit->object, options);
 	if (err)
 		return err;
-	if (!commit->tree) {
+	if (!commit->maybe_tree) {
 		err = report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", sha1_to_hex(tree_sha1));
 		if (err)
 			return err;