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.
# Copyright (c) 2016-present, Gregory Szorc
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license. See the LICENSE file for details.
import distutils.ccompiler
import os
from distutils.extension import Extension
zstd_sources = [
"zstd/%s" % p
for p in (
"common/debug.c",
"common/entropy_common.c",
"common/error_private.c",
"common/fse_decompress.c",
"common/pool.c",
"common/threading.c",
"common/xxhash.c",
"common/zstd_common.c",
"compress/fse_compress.c",
"compress/hist.c",
"compress/huf_compress.c",
"compress/zstd_compress_literals.c",
"compress/zstd_compress_sequences.c",
"compress/zstd_compress.c",
"compress/zstd_double_fast.c",
"compress/zstd_fast.c",
"compress/zstd_lazy.c",
"compress/zstd_ldm.c",
"compress/zstd_opt.c",
"compress/zstdmt_compress.c",
"decompress/huf_decompress.c",
"decompress/zstd_ddict.c",
"decompress/zstd_decompress.c",
"decompress/zstd_decompress_block.c",
"dictBuilder/cover.c",
"dictBuilder/divsufsort.c",
"dictBuilder/fastcover.c",
"dictBuilder/zdict.c",
)
]
zstd_sources_legacy = [
"zstd/%s" % p
for p in (
"deprecated/zbuff_common.c",
"deprecated/zbuff_compress.c",
"deprecated/zbuff_decompress.c",
"legacy/zstd_v01.c",
"legacy/zstd_v02.c",
"legacy/zstd_v03.c",
"legacy/zstd_v04.c",
"legacy/zstd_v05.c",
"legacy/zstd_v06.c",
"legacy/zstd_v07.c",
)
]
zstd_includes = [
"zstd",
"zstd/common",
"zstd/compress",
"zstd/decompress",
"zstd/dictBuilder",
]
zstd_includes_legacy = [
"zstd/deprecated",
"zstd/legacy",
]
ext_includes = [
"c-ext",
"zstd/common",
]
ext_sources = [
"zstd/common/error_private.c",
"zstd/common/pool.c",
"zstd/common/threading.c",
"zstd/common/zstd_common.c",
"zstd.c",
"c-ext/bufferutil.c",
"c-ext/compressiondict.c",
"c-ext/compressobj.c",
"c-ext/compressor.c",
"c-ext/compressoriterator.c",
"c-ext/compressionchunker.c",
"c-ext/compressionparams.c",
"c-ext/compressionreader.c",
"c-ext/compressionwriter.c",
"c-ext/constants.c",
"c-ext/decompressobj.c",
"c-ext/decompressor.c",
"c-ext/decompressoriterator.c",
"c-ext/decompressionreader.c",
"c-ext/decompressionwriter.c",
"c-ext/frameparams.c",
]
zstd_depends = [
"c-ext/python-zstandard.h",
]
def get_c_extension(
support_legacy=False,
system_zstd=False,
name="zstd",
warnings_as_errors=False,
root=None,
):
"""Obtain a distutils.extension.Extension for the C extension.
``support_legacy`` controls whether to compile in legacy zstd format support.
``system_zstd`` controls whether to compile against the system zstd library.
For this to work, the system zstd library and headers must match what
python-zstandard is coded against exactly.
``name`` is the module name of the C extension to produce.
``warnings_as_errors`` controls whether compiler warnings are turned into
compiler errors.
``root`` defines a root path that source should be computed as relative
to. This should be the directory with the main ``setup.py`` that is
being invoked. If not defined, paths will be relative to this file.
"""
actual_root = os.path.abspath(os.path.dirname(__file__))
root = root or actual_root
sources = set([os.path.join(actual_root, p) for p in ext_sources])
if not system_zstd:
sources.update([os.path.join(actual_root, p) for p in zstd_sources])
if support_legacy:
sources.update(
[os.path.join(actual_root, p) for p in zstd_sources_legacy]
)
sources = list(sources)
include_dirs = set([os.path.join(actual_root, d) for d in ext_includes])
if not system_zstd:
include_dirs.update(
[os.path.join(actual_root, d) for d in zstd_includes]
)
if support_legacy:
include_dirs.update(
[os.path.join(actual_root, d) for d in zstd_includes_legacy]
)
include_dirs = list(include_dirs)
depends = [os.path.join(actual_root, p) for p in zstd_depends]
compiler = distutils.ccompiler.new_compiler()
# Needed for MSVC.
if hasattr(compiler, "initialize"):
compiler.initialize()
if compiler.compiler_type == "unix":
compiler_type = "unix"
elif compiler.compiler_type == "msvc":
compiler_type = "msvc"
elif compiler.compiler_type == "mingw32":
compiler_type = "mingw32"
else:
raise Exception("unhandled compiler type: %s" % compiler.compiler_type)
extra_args = ["-DZSTD_MULTITHREAD"]
if not system_zstd:
extra_args.append("-DZSTDLIB_VISIBILITY=")
extra_args.append("-DZDICTLIB_VISIBILITY=")
extra_args.append("-DZSTDERRORLIB_VISIBILITY=")
if compiler_type == "unix":
extra_args.append("-fvisibility=hidden")
if not system_zstd and support_legacy:
extra_args.append("-DZSTD_LEGACY_SUPPORT=1")
if warnings_as_errors:
if compiler_type in ("unix", "mingw32"):
extra_args.append("-Werror")
elif compiler_type == "msvc":
extra_args.append("/WX")
else:
assert False
libraries = ["zstd"] if system_zstd else []
# Python 3.7 doesn't like absolute paths. So normalize to relative.
sources = [os.path.relpath(p, root) for p in sources]
include_dirs = [os.path.relpath(p, root) for p in include_dirs]
depends = [os.path.relpath(p, root) for p in depends]
# TODO compile with optimizations.
return Extension(
name,
sources,
include_dirs=include_dirs,
depends=depends,
extra_compile_args=extra_args,
libraries=libraries,
)