phases: avoid a potentially costly dictionary interation in some case
If we retract for the draft phase, there is not non-public item to be retracted
and we can skip this part. This part is was apparently super costly thanks to
Python.
On mozilla-try-2019-02-18, a perf::unbundle call with a 10 000 changesets
bundle gives give use the following timing.
e57d4b868a3e: 4.6 seconds
ac1c75188440: 102.5 seconds
this-changeset: 30.0 seconds
So we recovered about ⅔ of the regression, the next changeset will give us the
rest back.
--- a/mercurial/phases.py Thu Mar 21 12:24:42 2024 +0100
+++ b/mercurial/phases.py Mon Mar 25 01:50:31 2024 +0100
@@ -907,9 +907,10 @@
replaced_roots.add(r)
sets = self._phasesets
sets[targetphase].update(changed_revs)
- for r, old in changed_revs.items():
- if old > public:
- sets[old].discard(r)
+ if targetphase > draft:
+ for r, old in changed_revs.items():
+ if old > public:
+ sets[old].discard(r)
if new_roots:
assert changed_revs