procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
#!/usr/bin/env python3
# Search for interesting discovery instance
#
# search-discovery-case REPO [REPO]…
#
# This use a subsetmaker extension (next to this script) to generate a steam of
# random discovery instance. When interesting case are discovered, information
# about them are print on the stdout.
import json
import os
import queue
import random
import signal
import subprocess
import sys
import threading
this_script = os.path.abspath(sys.argv[0])
this_dir = os.path.dirname(this_script)
hg_dir = os.path.join(this_dir, '..', '..')
HG_REPO = os.path.normpath(hg_dir)
HG_BIN = os.path.join(HG_REPO, 'hg')
JOB = int(os.environ.get('NUMBER_OF_PROCESSORS', 8))
SLICING = ('scratch', 'randomantichain', 'rev')
def nb_revs(repo_path):
cmd = [
HG_BIN,
'--repository',
repo_path,
'log',
'--template',
'{rev}',
'--rev',
'tip',
]
s = subprocess.Popen(cmd, stdout=subprocess.PIPE)
out, err = s.communicate()
return int(out)
repos = []
for repo in sys.argv[1:]:
size = nb_revs(repo)
repos.append((repo, size))
def pick_one(repo):
pick = random.choice(SLICING)
seed = random.randint(0, 100000)
if pick == 'scratch':
start = int(repo[1] * 0.3)
end = int(repo[1] * 0.7)
nb = random.randint(start, end)
return ('scratch', nb, seed)
elif pick == 'randomantichain':
return ('randomantichain', seed)
elif pick == 'rev':
start = int(repo[1] * 0.3)
end = int(repo[1])
rev = random.randint(start, end)
return ('rev', rev)
else:
assert False
done = threading.Event()
cases = queue.Queue(maxsize=10 * JOB)
results = queue.Queue()
def worker():
while not done.is_set():
c = cases.get()
if c is None:
return
try:
res = process(c)
results.put((c, res))
except Exception as exc:
print('processing-failed: %s %s' % (c, exc), file=sys.stderr)
c = (c[0], c[2], c[1])
try:
res = process(c)
results.put((c, res))
except Exception as exc:
print('processing-failed: %s %s' % (c, exc), file=sys.stderr)
SUBSET_PATH = os.path.join(HG_REPO, 'contrib', 'perf-utils', 'subsetmaker.py')
CMD_BASE = (
HG_BIN,
'debugdiscovery',
'--template',
'json',
'--config',
'extensions.subset=%s' % SUBSET_PATH,
)
# '--local-as-revs "$left" --local-as-revs "$right"'
# > /data/discovery-references/results/disco-mozilla-unified-$1-$2.txt
# )
def to_revsets(case):
t = case[0]
if t == 'scratch':
return 'not scratch(all(), %d, "%d")' % (case[1], case[2])
elif t == 'randomantichain':
return '::randomantichain(all(), "%d")' % case[1]
elif t == 'rev':
return '::%d' % case[1]
else:
assert False
def process(case):
(repo, left, right) = case
cmd = list(CMD_BASE)
cmd.append('-R')
cmd.append(repo[0])
cmd.append('--local-as-revs')
cmd.append(to_revsets(left))
cmd.append('--remote-as-revs')
cmd.append(to_revsets(right))
s = subprocess.Popen(cmd, stdout=subprocess.PIPE)
out, err = s.communicate()
return json.loads(out)[0]
def interesting_boundary(res):
"""check if a case is interesting or not
For now we are mostly interrested in case were we do multiple roundstrip
and where the boundary is somewhere in the middle of the undecided set.
Ideally, we would make this configurable, but this is not a focus for now
return None or (
round-trip,
undecided-common,
undecided-missing,
total-revs,
common-revs,
missing-revs,
)
"""
roundtrips = res["total-roundtrips"]
if roundtrips <= 1:
return None
total_revs = res["nb-revs"]
common_revs = res["nb-revs-common"]
missing_revs = res["nb-revs-missing"]
undecided_common = res["nb-ini_und-common"]
undecided_missing = res["nb-ini_und-missing"]
if undecided_common == 0:
return None
if undecided_missing == 0:
return None
return (
roundtrips,
undecided_common,
undecided_missing,
total_revs,
common_revs,
missing_revs,
)
def end(*args, **kwargs):
done.set()
def format_case(case):
return '-'.join(str(s) for s in case)
signal.signal(signal.SIGINT, end)
for i in range(JOB):
threading.Thread(target=worker).start()
nb_cases = 0
while not done.is_set():
repo = random.choice(repos)
left = pick_one(repo)
right = pick_one(repo)
cases.put((repo, left, right))
while not results.empty():
# results has a single reader so this is fine
c, res = results.get_nowait()
boundary = interesting_boundary(res)
if boundary is not None:
print(c[0][0], format_case(c[1]), format_case(c[2]), *boundary)
sys.stdout.flush()
nb_cases += 1
if not nb_cases % 100:
print('[%d cases generated]' % nb_cases, file=sys.stderr)
for i in range(JOB):
try:
cases.put_nowait(None)
except queue.Full:
pass
print('[%d cases generated]' % nb_cases, file=sys.stderr)
print('[ouput generation is over]' % nb_cases, file=sys.stderr)