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.
# mercurial.revlogutils -- basic utilities for revlog
#
# Copyright 2019 Pierre-Yves David <pierre-yves.david@octobus.net>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from ..thirdparty import attr
from ..interfaces import repository
# See mercurial.revlogutils.constants for doc
COMP_MODE_INLINE = 2
RANK_UNKNOWN = -1
def offset_type(offset, type):
if (type & ~repository.REVISION_FLAGS_KNOWN) != 0:
raise ValueError(b'unknown revlog index flags: %d' % type)
return int(int(offset) << 16 | type)
def entry(
data_offset,
data_compressed_length,
data_delta_base,
link_rev,
parent_rev_1,
parent_rev_2,
node_id,
flags=0,
data_uncompressed_length=-1,
data_compression_mode=COMP_MODE_INLINE,
sidedata_offset=0,
sidedata_compressed_length=0,
sidedata_compression_mode=COMP_MODE_INLINE,
rank=RANK_UNKNOWN,
):
"""Build one entry from symbolic name
This is useful to abstract the actual detail of how we build the entry
tuple for caller who don't care about it.
This should always be called using keyword arguments. Some arguments have
default value, this match the value used by index version that does not store such data.
"""
return (
offset_type(data_offset, flags),
data_compressed_length,
data_uncompressed_length,
data_delta_base,
link_rev,
parent_rev_1,
parent_rev_2,
node_id,
sidedata_offset,
sidedata_compressed_length,
data_compression_mode,
sidedata_compression_mode,
rank,
)
@attr.s(slots=True, frozen=True)
class revisioninfo:
"""Information about a revision that allows building its fulltext
node: expected hash of the revision
p1, p2: parent revs of the revision
btext: built text cache consisting of a one-element list
cachedelta: (baserev, uncompressed_delta) or None
flags: flags associated to the revision storage
One of btext[0] or cachedelta must be set.
"""
node = attr.ib()
p1 = attr.ib()
p2 = attr.ib()
btext = attr.ib()
textlen = attr.ib()
cachedelta = attr.ib()
flags = attr.ib()