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.
# unit tests for mercuril.util utilities
import contextlib
import io
import itertools
import unittest
from mercurial import pycompat, util, utils
@contextlib.contextmanager
def mocktimer(incr=0.1, *additional_targets):
"""Replaces util.timer and additional_targets with a mock
The timer starts at 0. On each call the time incremented by the value
of incr. If incr is an iterable, then the time is incremented by the
next value from that iterable, looping in a cycle when reaching the end.
additional_targets must be a sequence of (object, attribute_name) tuples;
the mock is set with setattr(object, attribute_name, mock).
"""
time = [0]
try:
incr = itertools.cycle(incr)
except TypeError:
incr = itertools.repeat(incr)
def timer():
time[0] += next(incr)
return time[0]
# record original values
orig = util.timer
additional_origs = [(o, a, getattr(o, a)) for o, a in additional_targets]
# mock out targets
util.timer = timer
for obj, attr in additional_targets:
setattr(obj, attr, timer)
try:
yield
finally:
# restore originals
util.timer = orig
for args in additional_origs:
setattr(*args)
# attr.s default factory for util.timedstats.start binds the timer we
# need to mock out.
_start_default = (util.timedcmstats.start.default, 'factory')
@contextlib.contextmanager
def capturestderr():
"""Replace utils.procutil.stderr with an io.BytesIO instance
The instance is made available as the return value of __enter__.
This contextmanager is reentrant.
"""
orig = utils.procutil.stderr
utils.procutil.stderr = io.BytesIO()
try:
yield utils.procutil.stderr
finally:
utils.procutil.stderr = orig
class timedtests(unittest.TestCase):
def testtimedcmstatsstr(self):
stats = util.timedcmstats()
self.assertEqual(str(stats), '<unknown>')
self.assertEqual(bytes(stats), b'<unknown>')
stats.elapsed = 12.34
self.assertEqual(str(stats), pycompat.sysstr(util.timecount(12.34)))
self.assertEqual(bytes(stats), util.timecount(12.34))
def testtimedcmcleanexit(self):
# timestamps 1, 4, elapsed time of 4 - 1 = 3
with mocktimer([1, 3], _start_default):
with util.timedcm('pass') as stats:
# actual context doesn't matter
pass
self.assertEqual(stats.start, 1)
self.assertEqual(stats.elapsed, 3)
self.assertEqual(stats.level, 1)
def testtimedcmnested(self):
# timestamps 1, 3, 6, 10, elapsed times of 6 - 3 = 3 and 10 - 1 = 9
with mocktimer([1, 2, 3, 4], _start_default):
with util.timedcm('outer') as outer_stats:
with util.timedcm('inner') as inner_stats:
# actual context doesn't matter
pass
self.assertEqual(outer_stats.start, 1)
self.assertEqual(outer_stats.elapsed, 9)
self.assertEqual(outer_stats.level, 1)
self.assertEqual(inner_stats.start, 3)
self.assertEqual(inner_stats.elapsed, 3)
self.assertEqual(inner_stats.level, 2)
def testtimedcmexception(self):
# timestamps 1, 4, elapsed time of 4 - 1 = 3
with mocktimer([1, 3], _start_default):
try:
with util.timedcm('exceptional') as stats:
raise ValueError()
except ValueError:
pass
self.assertEqual(stats.start, 1)
self.assertEqual(stats.elapsed, 3)
self.assertEqual(stats.level, 1)
def testtimeddecorator(self):
@util.timed
def testfunc(callcount=1):
callcount -= 1
if callcount:
testfunc(callcount)
# timestamps 1, 2, 3, 4, elapsed time of 3 - 2 = 1 and 4 - 1 = 3
with mocktimer(1, _start_default):
with capturestderr() as out:
testfunc(2)
self.assertEqual(
out.getvalue(),
(b' testfunc: 1.000 s\n' b' testfunc: 3.000 s\n'),
)
if __name__ == '__main__':
import silenttestrunner
silenttestrunner.main(__name__)