Optimize the three-way merge of git-read-tree

As mentioned, the three-way case *should* be as trivial as the
following. It passes all the tests, and I verified that a conflicting
merge in the 100,000 file horror-case merged correctly (with the conflict
markers) in 0.687 seconds with this, so it works, but I'm lazy and
somebody else should double-check it [jc: followed all three-way merge
codepaths and verified it removes when it should].

Without this patch, the merge took 8.355 seconds, so this patch
really does make a huge difference for merge performance with lots and
lots of files, and we're not talking percentages, we're talking
orders-of-magnitude differences!

Now "unpack_trees()" is just fast enough that we don't need to avoid it
(although it's probably still a good idea to eventually convert it to use
the traverse_trees() infrastructure some day - just to avoid having
extraneous tree traversal functions).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Linus Torvalds 2007-08-10 12:53:51 -07:00 committed by Junio C Hamano
parent cbbb218f8b
commit 566b5c057c

View File

@ -667,7 +667,6 @@ int threeway_merge(struct cache_entry **stages,
int no_anc_exists = 1;
int i;
remove_entry(remove);
for (i = 1; i < o->head_idx; i++) {
if (!stages[i] || stages[i] == o->df_conflict_entry)
any_anc_missing = 1;
@ -730,8 +729,10 @@ int threeway_merge(struct cache_entry **stages,
}
/* #1 */
if (!head && !remote && any_anc_missing)
if (!head && !remote && any_anc_missing) {
remove_entry(remove);
return 0;
}
/* Under the new "aggressive" rule, we resolve mostly trivial
* cases that we historically had git-merge-one-file resolve.
@ -763,6 +764,7 @@ int threeway_merge(struct cache_entry **stages,
if ((head_deleted && remote_deleted) ||
(head_deleted && remote && remote_match) ||
(remote_deleted && head && head_match)) {
remove_entry(remove);
if (index)
return deleted_entry(index, index, o);
else if (ce && !head_deleted)
@ -785,6 +787,7 @@ int threeway_merge(struct cache_entry **stages,
verify_uptodate(index, o);
}
remove_entry(remove);
o->nontrivial_merge = 1;
/* #2, #3, #4, #6, #7, #9, #10, #11. */