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.

     1

# Disable the $CAP wire protocol capability.

     2

     3

if test -z "$CAP"

     4

then

     5

    echo "CAP environment variable not set."

     6

fi

     7

     8

cat > notcapable-$CAP.py << EOF

     9

from mercurial import extensions, localrepo

    10

from mercurial.interfaces import repository

    11

def extsetup(ui):

    12

    extensions.wrapfunction(repository.peer, 'capable', wrapcapable)

    13

    extensions.wrapfunction(localrepo.localrepository, 'peer', wrappeer)

    14

def wrapcapable(orig, self, name, *args, **kwargs):

    15

    if name in b'$CAP'.split(b' '):

    16

        return False

    17

    return orig(self, name, *args, **kwargs)

    18

def wrappeer(orig, self, *args, **kwargs):

    19

    # Since we're disabling some newer features, we need to make sure local

    20

    # repos add in the legacy features again.

    21

    return localrepo.locallegacypeer(self, *args, **kwargs)

    22

EOF

    23

    24

echo '[extensions]' >> $HGRCPATH

    25

echo "notcapable-$CAP = `pwd`/notcapable-$CAP.py" >> $HGRCPATH