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.
# debugshell extension
"""a python shell with repo, changelog & manifest objects"""
import code
import mercurial
import sys
from mercurial import (
demandimport,
pycompat,
registrar,
)
cmdtable = {}
command = registrar.command(cmdtable)
def pdb(ui, repo, msg, **opts):
objects = {
'mercurial': mercurial,
'repo': repo,
'cl': repo.changelog,
'mf': repo.manifestlog,
}
code.interact(msg, local=objects)
def ipdb(ui, repo, msg, **opts):
import IPython
cl = repo.changelog
mf = repo.manifestlog
cl, mf # use variables to appease pyflakes
IPython.embed()
@command(b'debugshell|dbsh', [])
def debugshell(ui, repo, **opts):
bannermsg = "loaded repo : %s\n" "using source: %s" % (
pycompat.sysstr(repo.root),
mercurial.__path__[0],
)
pdbmap = {'pdb': 'code', 'ipdb': 'IPython'}
debugger = ui.config(b"ui", b"debugger")
if not debugger:
debugger = 'pdb'
else:
debugger = pycompat.sysstr(debugger)
# if IPython doesn't exist, fallback to code.interact
try:
with demandimport.deactivated():
__import__(pdbmap[debugger])
except ImportError:
ui.warnnoi18n(
b"%s debugger specified but %s module was not found\n"
% (debugger, pdbmap[debugger])
)
debugger = b'pdb'
getattr(sys.modules[__name__], debugger)(ui, repo, bannermsg, **opts)