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.
import sys
import unittest
from mercurial.node import wdirrev
from mercurial import error
from mercurial.testing import revlog as revlogtesting
try:
from mercurial import rustext
rustext.__name__ # trigger immediate actual import
except ImportError:
rustext = None
else:
# this would fail already without appropriate ancestor.__package__
from mercurial.rustext.ancestor import (
AncestorsIterator,
LazyAncestors,
MissingAncestors,
)
from mercurial.rustext import dagop
try:
from mercurial.cext import parsers as cparsers
except ImportError:
cparsers = None
@unittest.skipIf(
rustext is None,
'The Rust version of the "ancestor" module is not available. It is needed'
' for this test.',
)
@unittest.skipIf(
rustext is None,
'The Rust or C version of the "parsers" module, which the "ancestor" module'
' relies on, is not available.',
)
class rustancestorstest(revlogtesting.RevlogBasedTestBase):
"""Test the correctness of binding to Rust code.
This test is merely for the binding to Rust itself: extraction of
Python variable, giving back the results etc.
It is not meant to test the algorithmic correctness of the operations
on ancestors it provides. Hence the very simple embedded index data is
good enough.
Algorithmic correctness is asserted by the Rust unit tests.
"""
def testiteratorrevlist(self):
idx = self.parseindex()
# checking test assumption about the index binary data:
self.assertEqual(
{i: (r[5], r[6]) for i, r in enumerate(idx)},
{0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)},
)
ait = AncestorsIterator(idx, [3], 0, True)
self.assertEqual([r for r in ait], [3, 2, 1, 0])
ait = AncestorsIterator(idx, [3], 0, False)
self.assertEqual([r for r in ait], [2, 1, 0])
def testlazyancestors(self):
idx = self.parseindex()
start_count = sys.getrefcount(idx) # should be 2 (see Python doc)
self.assertEqual(
{i: (r[5], r[6]) for i, r in enumerate(idx)},
{0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)},
)
lazy = LazyAncestors(idx, [3], 0, True)
# we have two more references to the index:
# - in its inner iterator for __contains__ and __bool__
# - in the LazyAncestors instance itself (to spawn new iterators)
self.assertEqual(sys.getrefcount(idx), start_count + 2)
self.assertTrue(2 in lazy)
self.assertTrue(bool(lazy))
self.assertEqual(list(lazy), [3, 2, 1, 0])
# a second time to validate that we spawn new iterators
self.assertEqual(list(lazy), [3, 2, 1, 0])
# now let's watch the refcounts closer
ait = iter(lazy)
self.assertEqual(sys.getrefcount(idx), start_count + 3)
del ait
self.assertEqual(sys.getrefcount(idx), start_count + 2)
del lazy
self.assertEqual(sys.getrefcount(idx), start_count)
# let's check bool for an empty one
self.assertFalse(LazyAncestors(idx, [0], 0, False))
def testmissingancestors(self):
idx = self.parseindex()
missanc = MissingAncestors(idx, [1])
self.assertTrue(missanc.hasbases())
self.assertEqual(missanc.missingancestors([3]), [2, 3])
missanc.addbases({2})
self.assertEqual(missanc.bases(), {1, 2})
self.assertEqual(missanc.missingancestors([3]), [3])
self.assertEqual(missanc.basesheads(), {2})
def testmissingancestorsremove(self):
idx = self.parseindex()
missanc = MissingAncestors(idx, [1])
revs = {0, 1, 2, 3}
missanc.removeancestorsfrom(revs)
self.assertEqual(revs, {2, 3})
def testrefcount(self):
idx = self.parseindex()
start_count = sys.getrefcount(idx)
# refcount increases upon iterator init...
ait = AncestorsIterator(idx, [3], 0, True)
self.assertEqual(sys.getrefcount(idx), start_count + 1)
self.assertEqual(next(ait), 3)
# and decreases once the iterator is removed
del ait
self.assertEqual(sys.getrefcount(idx), start_count)
# and removing ref to the index after iterator init is no issue
ait = AncestorsIterator(idx, [3], 0, True)
del idx
self.assertEqual(list(ait), [3, 2, 1, 0])
def testgrapherror(self):
data = (
revlogtesting.data_non_inlined[: 64 + 27]
+ b'\xf2'
+ revlogtesting.data_non_inlined[64 + 28 :]
)
idx = cparsers.parse_index2(data, False)[0]
with self.assertRaises(rustext.GraphError) as arc:
AncestorsIterator(idx, [1], -1, False)
exc = arc.exception
self.assertIsInstance(exc, ValueError)
# rust-cpython issues appropriate str instances for Python 2 and 3
self.assertEqual(exc.args, ('ParentOutOfRange', 1))
def testwdirunsupported(self):
# trying to access ancestors of the working directory raises
# WdirUnsupported directly
idx = self.parseindex()
with self.assertRaises(error.WdirUnsupported):
list(AncestorsIterator(idx, [wdirrev], -1, False))
def testheadrevs(self):
idx = self.parseindex()
self.assertEqual(dagop.headrevs(idx, [1, 2, 3]), {3})
if __name__ == '__main__':
import silenttestrunner
silenttestrunner.main(__name__)