push: rework the computation of fallbackheads to be correct
The previous computation tried to be smart but ended up being wrong. This was
caught by phase movement test while reworking the phase discovery logic to be
faster.
The previous logic was failing to catch case where the pushed set was not based
on a common heads (i.e. when the discovery seemed to have "over discovered"
content, outside the pushed set)
In the following graph, `e` is a common head and we `hg push -r f`. We need to
detect `c` as a fallback heads and we previous failed to do so::
e
|
d f
|/
c
|
b
|
a
The performance impact of the change seems minimal. On the most impacted
repository at hand (mozilla-try), the slowdown seems mostly mixed in the
overall noise `hg push` but seems to be in the hundred of milliseconds order of
magnitude. When using rust, we seems to be a bit faster, probably because we
leverage more accelaratd internals.
I added a couple of performance related common for further investigation later
on.
Enable obsolete markers
$ cat >> $HGRCPATH << EOF
> [experimental]
> evolution.createmarkers=True
> [phases]
> publish=False
> EOF
Build a repo with some cacheable bits:
$ hg init a
$ cd a
$ echo a > a
$ hg ci -qAm0
$ hg tag t1
$ hg book -i bk1
$ hg branch -q b2
$ hg ci -Am1
$ hg tag t2
$ echo dumb > dumb
$ hg ci -qAmdumb
$ hg debugobsolete b1174d11b69e63cb0c5726621a43c859f0858d7f
1 new obsolescence markers
obsoleted 1 changesets
$ hg phase -pr t1
$ hg phase -fsr t2
Make a helper function to check cache damage invariants:
- command output shouldn't change
- cache should be present after first use
- corruption/repair should be silent (no exceptions or warnings)
- cache should survive deletion, overwrite, and append
- unreadable / unwriteable caches should be ignored
- cache should be rebuilt after corruption
$ damage() {
> CMD=$1
> CACHE=.hg/cache/$2
> CLEAN=$3
> hg $CMD > before
> test -f $CACHE || echo "not present"
> echo bad > $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> "$RUNTESTDIR/pdiff" before after || echo "*** overwrite corruption"
> echo corruption >> $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> "$RUNTESTDIR/pdiff" before after || echo "*** append corruption"
> rm $CACHE
> mkdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> "$RUNTESTDIR/pdiff" before after || echo "*** read-only corruption"
> test -d $CACHE || echo "*** directory clobbered"
> rmdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> "$RUNTESTDIR/pdiff" before after || echo "*** missing corruption"
> test -f $CACHE || echo "not rebuilt"
> }
Beat up tags caches:
$ damage "tags --hidden" tags2
$ damage tags tags2-visible
$ damage "tag -f t3" hgtagsfnodes1
1 new orphan changesets
1 new orphan changesets
1 new orphan changesets
1 new orphan changesets
1 new orphan changesets
Beat up branch caches:
$ damage branches branch2-base "rm .hg/cache/branch2-[vs]*"
$ damage branches branch2-served "rm .hg/cache/branch2-[bv]*"
$ damage branches branch2-visible
$ damage "log -r branch(.)" rbc-names-v1
$ damage "log -r branch(default)" rbc-names-v1
$ damage "log -r branch(b2)" rbc-revs-v1
We currently can't detect an rbc cache with unknown names:
$ damage "log -qr branch(b2)" rbc-names-v1
--- before * (glob)
+++ after * (glob)
@@ -1,8 +?,0 @@ (glob)
-2:5fb7d38b9dc4
-3:60b597ffdafa
-4:b1174d11b69e
-5:6354685872c0
-6:5ebc725f1bef
-7:7b76eec2f273
-8:ef3428d9d644
-9:ba7a936bc03c
*** append corruption