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
#
# check-perf-code - (historical) portability checker for contrib/perf.py
import os
import sys
# write static check patterns here
perfpypats = [
[
(
r'(branchmap|repoview|repoviewutil)\.subsettable',
"use getbranchmapsubsettable() for early Mercurial",
),
(
r'\.(vfs|svfs|opener|sopener)',
"use getvfs()/getsvfs() for early Mercurial",
),
(
r'ui\.configint',
"use getint() instead of ui.configint() for early Mercurial",
),
],
# warnings
[],
]
def modulewhitelist(names):
replacement = [
('.py', ''),
('.c', ''), # trim suffix
('mercurial%s' % '/', ''), # trim "mercurial/" path
]
ignored = {'__init__'}
modules = {}
# convert from file name to module name, and count # of appearances
for name in names:
name = name.strip()
for old, new in replacement:
name = name.replace(old, new)
if name not in ignored:
modules[name] = modules.get(name, 0) + 1
# list up module names, which appear multiple times
whitelist = []
for name, count in modules.items():
if count > 1:
whitelist.append(name)
return whitelist
if __name__ == "__main__":
# in this case, it is assumed that result of "hg files" at
# multiple revisions is given via stdin
whitelist = modulewhitelist(sys.stdin)
assert whitelist, "module whitelist is empty"
# build up module whitelist check from file names given at runtime
perfpypats[0].append(
# this matching pattern assumes importing modules from
# "mercurial" package in the current style below, for simplicity
#
# from mercurial import (
# foo,
# bar,
# baz
# )
(
(
r'from mercurial import [(][a-z0-9, \n#]*\n(?! *%s,|^[ #]*\n|[)])'
% ',| *'.join(whitelist)
),
"import newer module separately in try clause for early Mercurial",
)
)
# import contrib/check-code.py as checkcode
assert 'RUNTESTDIR' in os.environ, "use check-perf-code.py in *.t script"
contribpath = os.path.join(os.environ['RUNTESTDIR'], '..', 'contrib')
sys.path.insert(0, contribpath)
checkcode = __import__('check-code')
# register perf.py specific entry with "checks" in check-code.py
checkcode.checks.append(
('perf.py', r'contrib/perf.py$', '', checkcode.pyfilters, perfpypats)
)
sys.exit(checkcode.main())