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
#
# simple script to be used in hooks
#
# put something like this in the repo .hg/hgrc:
#
# [hooks]
# changegroup = python "$TESTDIR/printenv.py" <hookname> [exit] [output]
#
# - <hookname> is a mandatory argument (e.g. "changegroup")
# - [exit] is the exit code of the hook (default: 0)
# - [output] is the name of the output file (default: use sys.stdout)
# the file will be opened in append mode.
#
import argparse
import os
import sys
try:
import msvcrt
msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
pass
parser = argparse.ArgumentParser()
parser.add_argument("name", help="the hook name, used for display")
parser.add_argument(
"exitcode",
nargs="?",
default=0,
type=int,
help="the exit code for the hook",
)
parser.add_argument(
"out", nargs="?", default=None, help="where to write the output"
)
parser.add_argument(
"--line",
action="store_true",
help="print environment variables one per line instead of on a single line",
)
args = parser.parse_args()
if args.out is None:
out = sys.stdout
out = getattr(out, "buffer", out)
else:
out = open(args.out, "ab")
# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [(k, v) for k, v in os.environ.items() if k.startswith("HG_") and v]
env.sort()
out.write(b"%s hook: " % args.name.encode('ascii'))
if os.name == 'nt':
filter = lambda x: x.replace('\\', '/')
else:
filter = lambda x: x
vars = [
b"%s=%s" % (k.encode('ascii'), filter(v).encode('ascii')) for k, v in env
]
# Print variables on out
if not args.line:
out.write(b" ".join(vars))
else:
for var in vars:
out.write(var)
out.write(b"\n")
out.write(b"\n")
out.close()
sys.exit(args.exitcode)