# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1711327831 -3600
# Node ID e0f92bd98c24a2f87f47c9820821b6d401bbce0b
# Parent  394ea442816342a7b6f872614c71a9b3c9c10fb2
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.

diff -r 394ea4428163 -r e0f92bd98c24 mercurial/phases.py
--- 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