This updates the codepath to write commit objects so that when a commit is
emitted, its parents are scheduled to be output next (but this does not go
recursively), in the hope that it may help a typical "rev-list" traversal.
I've tried various workloads from the previous message; while this patch
does not regress any of them significantly, it does not seem to improve
them significantly, either.
builtin/pack-objects.c | 96 ++++++++++++++++++++++++++++++++++-------------
1 files changed, 69 insertions(+), 27 deletions(-)
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 27132bb..46ae610 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -487,6 +487,74 @@ static void add_family_to_write_order(struct object_entry **wo,
add_descendants_to_write_order(wo, endp, root);
}
+static void add_commit_to_write_order(struct object_entry **wo,
+ int *endp,
+ struct object_entry *e)
+{
+ /*
+ * A typical rev-list traversal looks at the parent of a
+ * commit before deciding to emit the commit; if it ends up
+ * emitting this commit, it is likely that it needs an early
+ * access of its parents.
+ */
+ struct commit *commit;
+ struct commit_list *parents;
+
+ if (e->filled)
+ return;
+ add_to_write_order(wo, endp, e);
+ commit = lookup_commit(e->idx.sha1);
+ if (!commit ||
+ (!commit->object.parsed && parse_commit(commit)))
+ die("BUG: calling add_commit with a non-commit???");
+ for (parents = commit->parents; parents; parents = parents->next) {
+ struct object_entry *pe;
+ struct commit *parent = parents->item;
+ pe = locate_object_entry(parent->object.sha1);
+ if (pe)
+ add_to_write_order(wo, endp, pe);
+ }
+}
+
+static int add_commits_to_write_order(struct object_entry **wo)
+{
+ int i, wo_end;
+
+ /*
+ * Give the commits in the original recency order until
+ * we see a tagged tip.
+ */
+ for (i = wo_end = 0; i < nr_objects; i++) {
+ if (objects[i].type != OBJ_COMMIT)
+ continue;
+ if (objects[i].tagged)
+ break;
+ add_commit_to_write_order(wo, &wo_end, &objects[i]);
+ }
+
+ /*
+ * Then fill all the tagged tips.
+ */
+ for (i = 0; i < nr_objects; i++) {
+ if (objects[i].type != OBJ_COMMIT)
+ continue;
+ if (objects[i].tagged)
+ add_commit_to_write_order(wo, &wo_end, &objects[i]);
+ }
+
+ /*
+ * And then all remaining commits and tags.
+ */
+ for (i = 0; i < nr_objects; i++) {
+ if (objects[i].type == OBJ_COMMIT)
+ add_commit_to_write_order(wo, &wo_end, &objects[i]);
+ else if (objects[i].type != OBJ_TAG)
+ add_to_write_order(wo, &wo_end, &objects[i]);
+ }
+
+ return wo_end;
+}
+
static struct object_entry **compute_write_order(void)
{
int i, wo_end;
@@ -519,33 +587,7 @@ static struct object_entry **compute_write_order(void)
*/
for_each_tag_ref(mark_tagged, NULL);
- /*
- * Give the commits in the original recency order until
- * we see a tagged tip.
- */
- for (i = wo_end = 0; i < nr_objects; i++) {
- if (objects[i].tagged)
- break;
- add_to_write_order(wo, &wo_end, &objects[i]);
- }
-
- /*
- * Then fill all the tagged tips.
- */
- for (; i < nr_objects; i++) {
- if (objects[i].tagged)
- add_to_write_order(wo, &wo_end, &objects[i]);
- }
-
- /*
- * And then all remaining commits and tags.
- */
- for (i = 0; i < nr_objects; i++) {
- if (objects[i].type != OBJ_COMMIT &&
- objects[i].type != OBJ_TAG)
- continue;
- add_to_write_order(wo, &wo_end, &objects[i]);
- }
+ wo_end = add_commits_to_write_order(wo);
/*
* And then all the trees.
--
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