comparison mercurial/utils/procutil.py @ 45040:fd205a9c358a

procutil: factor out conditional creation of LineBufferedWrapper

At the same time, document the logic and generalize it to work on all Python
versions.

45039:2bfbd7d2c204

            orig.flush()
        return res


io.BufferedIOBase.register(LineBufferedWrapper)


# glibc determines buffering on first write to stdout - if we replace a TTY
# destined stdout with a pipe destined stdout (e.g. pager), we want line
# buffering (or unbuffered, on Windows)

        # Windows doesn't support line buffering
        stdout = os.fdopen(stdout.fileno(), 'wb', 0)
    elif pycompat.ispy3:
        # On Python 3, buffered binary streams can't be set line-buffered.
        # Therefore we have a wrapper that implements line buffering.
        if isinstance(stdout, io.BufferedIOBase) and not isinstance(
            stdout, LineBufferedWrapper
        ):
            stdout = LineBufferedWrapper(stdout)
    else:
        stdout = os.fdopen(stdout.fileno(), 'wb', 1)

if pycompat.iswindows:
    from .. import windows as platform

45040:fd205a9c358a

            orig.flush()
        return res


io.BufferedIOBase.register(LineBufferedWrapper)


def make_line_buffered(stream):
    if pycompat.ispy3 and not isinstance(stream, io.BufferedIOBase):
        # On Python 3, buffered streams can be expected to subclass
        # BufferedIOBase. This is definitively the case for the streams
        # initialized by the interpreter. For unbuffered streams, we don't need
        # to emulate line buffering.
        return stream
    if isinstance(stream, LineBufferedWrapper):
        return stream
    return LineBufferedWrapper(stream)


# glibc determines buffering on first write to stdout - if we replace a TTY
# destined stdout with a pipe destined stdout (e.g. pager), we want line
# buffering (or unbuffered, on Windows)

        # Windows doesn't support line buffering
        stdout = os.fdopen(stdout.fileno(), 'wb', 0)
    elif pycompat.ispy3:
        # On Python 3, buffered binary streams can't be set line-buffered.
        # Therefore we have a wrapper that implements line buffering.
        stdout = make_line_buffered(stdout)
    else:
        stdout = os.fdopen(stdout.fileno(), 'wb', 1)

if pycompat.iswindows:
    from .. import windows as platform