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.
#!/usr/bin/env python3
# Measure the performance of a list of revsets against multiple revisions
# defined by parameter. Checkout one by one and run perfrevset with every
# revset in the list to benchmark its performance.
#
# You should run this from the root of your mercurial repository.
#
# call with --help for details
import math
import optparse # cannot use argparse, python 2.7 only
import os
import re
import subprocess
import sys
DEFAULTVARIANTS = [
'plain',
'min',
'max',
'first',
'last',
'reverse',
'reverse+first',
'reverse+last',
'sort',
'sort+first',
'sort+last',
]
def check_output(*args, **kwargs):
kwargs.setdefault('stderr', subprocess.PIPE)
kwargs.setdefault('stdout', subprocess.PIPE)
proc = subprocess.Popen(*args, **kwargs)
output, error = proc.communicate()
if proc.returncode != 0:
raise subprocess.CalledProcessError(proc.returncode, ' '.join(args[0]))
return output
def update(rev):
"""update the repo to a revision"""
try:
subprocess.check_call(['hg', 'update', '--quiet', '--check', str(rev)])
check_output(
['make', 'local'], stderr=None
) # suppress output except for error/warning
except subprocess.CalledProcessError as exc:
print('update to revision %s failed, aborting' % rev, file=sys.stderr)
sys.exit(exc.returncode)
def hg(cmd, repo=None):
"""run a mercurial command
<cmd> is the list of command + argument,
<repo> is an optional repository path to run this command in."""
fullcmd = ['./hg']
if repo is not None:
fullcmd += ['-R', repo]
fullcmd += [
'--config',
'extensions.perf=' + os.path.join(contribdir, 'perf.py'),
]
fullcmd += cmd
return check_output(fullcmd, stderr=subprocess.STDOUT)
def perf(revset, target=None, contexts=False):
"""run benchmark for this very revset"""
try:
args = ['perfrevset']
if contexts:
args.append('--contexts')
args.append('--')
args.append(revset)
output = hg(args, repo=target)
return parseoutput(output)
except subprocess.CalledProcessError as exc:
print(
'abort: cannot run revset benchmark: %s' % exc.cmd, file=sys.stderr
)
if getattr(exc, 'output', None) is None: # no output before 2.7
print('(no output)', file=sys.stderr)
else:
print(exc.output, file=sys.stderr)
return None
outputre = re.compile(
br'! wall (\d+.\d+) comb (\d+.\d+) user (\d+.\d+) '
br'sys (\d+.\d+) \(best of (\d+)\)'
)
def parseoutput(output):
"""parse a textual output into a dict
We cannot just use json because we want to compare with old
versions of Mercurial that may not support json output.
"""
match = outputre.search(output)
if not match:
print('abort: invalid output:', file=sys.stderr)
print(output, file=sys.stderr)
sys.exit(1)
return {
'comb': float(match.group(2)),
'count': int(match.group(5)),
'sys': float(match.group(3)),
'user': float(match.group(4)),
'wall': float(match.group(1)),
}
def printrevision(rev):
"""print data about a revision"""
sys.stdout.write("Revision ")
sys.stdout.flush()
subprocess.check_call(
[
'hg',
'log',
'--rev',
str(rev),
'--template',
'{if(tags, " ({tags})")} ' '{rev}:{node|short}: {desc|firstline}\n',
]
)
def idxwidth(nbidx):
"""return the max width of number used for index
This is similar to log10(nbidx), but we use custom code here
because we start with zero and we'd rather not deal with all the
extra rounding business that log10 would imply.
"""
nbidx -= 1 # starts at 0
idxwidth = 0
while nbidx:
idxwidth += 1
nbidx //= 10
if not idxwidth:
idxwidth = 1
return idxwidth
def getfactor(main, other, field, sensitivity=0.05):
"""return the relative factor between values for 'field' in main and other
Return None if the factor is insignificant (less than <sensitivity>
variation)."""
factor = 1
if main is not None:
factor = other[field] / main[field]
low, high = 1 - sensitivity, 1 + sensitivity
if low < factor < high:
return None
return factor
def formatfactor(factor):
"""format a factor into a 4 char string
22%
156%
x2.4
x23
x789
x1e4
x5x7
"""
if factor is None:
return ' '
elif factor < 2:
return '%3i%%' % (factor * 100)
elif factor < 10:
return 'x%3.1f' % factor
elif factor < 1000:
return '%4s' % ('x%i' % factor)
else:
order = int(math.log(factor)) + 1
while math.log(factor) > 1:
factor //= 0
return 'x%ix%i' % (factor, order)
def formattiming(value):
"""format a value to strictly 8 char, dropping some precision if needed"""
if value < 10 ** 7:
return ('%.6f' % value)[:8]
else:
# value is HUGE very unlikely to happen (4+ month run)
return '%i' % value
_marker = object()
def printresult(variants, idx, data, maxidx, verbose=False, reference=_marker):
"""print a line of result to stdout"""
mask = '%%0%ii) %%s' % idxwidth(maxidx)
out = []
for var in variants:
if data[var] is None:
out.append('error ')
out.append(' ' * 4)
continue
out.append(formattiming(data[var]['wall']))
if reference is not _marker:
factor = None
if reference is not None:
factor = getfactor(reference[var], data[var], 'wall')
out.append(formatfactor(factor))
if verbose:
out.append(formattiming(data[var]['comb']))
out.append(formattiming(data[var]['user']))
out.append(formattiming(data[var]['sys']))
out.append('%6d' % data[var]['count'])
print(mask % (idx, ' '.join(out)))
def printheader(variants, maxidx, verbose=False, relative=False):
header = [' ' * (idxwidth(maxidx) + 1)]
for var in variants:
if not var:
var = 'iter'
if len(var) > 8:
var = var[:3] + '..' + var[-3:]
header.append('%-8s' % var)
if relative:
header.append(' ')
if verbose:
header.append('%-8s' % 'comb')
header.append('%-8s' % 'user')
header.append('%-8s' % 'sys')
header.append('%6s' % 'count')
print(' '.join(header))
def getrevs(spec):
"""get the list of rev matched by a revset"""
try:
out = check_output(['hg', 'log', '--template={rev}\n', '--rev', spec])
except subprocess.CalledProcessError as exc:
print("abort, can't get revision from %s" % spec, file=sys.stderr)
sys.exit(exc.returncode)
return [r for r in out.split() if r]
def applyvariants(revset, variant):
if variant == 'plain':
return revset
for var in variant.split('+'):
revset = '%s(%s)' % (var, revset)
return revset
helptext = """This script will run multiple variants of provided revsets using
different revisions in your mercurial repository. After the benchmark are run
summary output is provided. Use it to demonstrate speed improvements or pin
point regressions. Revsets to run are specified in a file (or from stdin), one
revsets per line. Line starting with '#' will be ignored, allowing insertion of
comments."""
parser = optparse.OptionParser(
usage="usage: %prog [options] <revs>", description=helptext
)
parser.add_option(
"-f",
"--file",
help="read revset from FILE (stdin if omitted)",
metavar="FILE",
)
parser.add_option("-R", "--repo", help="run benchmark on REPO", metavar="REPO")
parser.add_option(
"-v",
"--verbose",
action='store_true',
help="display all timing data (not just best total time)",
)
parser.add_option(
"",
"--variants",
default=','.join(DEFAULTVARIANTS),
help="comma separated list of variant to test "
"(eg: plain,min,sorted) (plain = no modification)",
)
parser.add_option(
'',
'--contexts',
action='store_true',
help='obtain changectx from results instead of integer revs',
)
(options, args) = parser.parse_args()
if not args:
parser.print_help()
sys.exit(255)
# the directory where both this script and the perf.py extension live.
contribdir = os.path.dirname(__file__)
revsetsfile = sys.stdin
if options.file:
revsetsfile = open(options.file)
revsets = [l.strip() for l in revsetsfile if not l.startswith('#')]
revsets = [l for l in revsets if l]
print("Revsets to benchmark")
print("----------------------------")
for idx, rset in enumerate(revsets):
print("%i) %s" % (idx, rset))
print("----------------------------")
print()
revs = []
for a in args:
revs.extend(getrevs(a))
variants = options.variants.split(',')
results = []
for r in revs:
print("----------------------------")
printrevision(r)
print("----------------------------")
update(r)
res = []
results.append(res)
printheader(variants, len(revsets), verbose=options.verbose)
for idx, rset in enumerate(revsets):
varres = {}
for var in variants:
varrset = applyvariants(rset, var)
data = perf(varrset, target=options.repo, contexts=options.contexts)
varres[var] = data
res.append(varres)
printresult(
variants, idx, varres, len(revsets), verbose=options.verbose
)
sys.stdout.flush()
print("----------------------------")
print(
"""
Result by revset
================
"""
)
print('Revision:')
for idx, rev in enumerate(revs):
sys.stdout.write('%i) ' % idx)
sys.stdout.flush()
printrevision(rev)
print()
print()
for ridx, rset in enumerate(revsets):
print("revset #%i: %s" % (ridx, rset))
printheader(variants, len(results), verbose=options.verbose, relative=True)
ref = None
for idx, data in enumerate(results):
printresult(
variants,
idx,
data[ridx],
len(results),
verbose=options.verbose,
reference=ref,
)
ref = data[ridx]
print()