mercurial/util.py

25405:220a220ed088

            return memoryview(sliceable)[offset:]

import subprocess
closefds = os.name == 'posix'

def popen2(cmd, env=None, newlines=False):
    # Setting bufsize to -1 lets the system decide the buffer size.
    # The default for bufsize is 0, meaning unbuffered. This leads to
    # poor performance on Mac OS X: http://bugs.python.org/issue4194
    p = subprocess.Popen(cmd, shell=True, bufsize=-1,

25406:be930f16a52a

            return memoryview(sliceable)[offset:]

import subprocess
closefds = os.name == 'posix'

_chunksize = 4096

class bufferedinputpipe(object):
    """a manually buffered input pipe

    Python will not let us use buffered IO and lazy reading with 'polling' at
    the same time. We cannot probe the buffer state and select will not detect
    that data are ready to read if they are already buffered.

    This class let us work around that by implementing its own buffering
    (allowing efficient readline) while offering a way to know if the buffer is
    empty from the output (allowing collaboration of the buffer with polling).

    This class lives in the 'util' module because it makes use of the 'os'
    module from the python stdlib.
    """

    def __init__(self, input):
        self._input = input
        self._buffer = []
        self._eof = False

    @property
    def hasbuffer(self):
        """True is any data is currently buffered

        This will be used externally a pre-step for polling IO. If there is
        already data then no polling should be set in place."""
        return bool(self._buffer)

    @property
    def closed(self):
        return self._input.closed

    def fileno(self):
        return self._input.fileno()

    def close(self):
        return self._input.close()

    def read(self, size):
        while (not self._eof) and (self._lenbuf < size):
            self._fillbuffer()
        return self._frombuffer(size)

    def readline(self, *args, **kwargs):
        if 1 < len(self._buffer):
            # this should not happen because both read and readline end with a
            # _frombuffer call that collapse it.
            self._buffer = [''.join(self._buffer)]
        lfi = -1
        if self._buffer:
            lfi = self._buffer[-1].find('\n')
        while (not self._eof) and lfi < 0:
            self._fillbuffer()
            if self._buffer:
                lfi = self._buffer[-1].find('\n')
        size = lfi + 1
        if lfi < 0: # end of file
            size = self._lenbuf
        elif 1 < len(self._buffer):
            # we need to take previous chunks into account
            size += self._lenbuf - len(self._buffer[-1])
        return self._frombuffer(size)

    @property
    def _lenbuf(self):
        """return the current lengh of buffered data"""
        return sum(len(d) for d in self._buffer)

    def _frombuffer(self, size):
        """return at most 'size' data from the buffer

        The data are removed from the buffer."""
        if size == 0 or not self._buffer:
            return ''
        buf = self._buffer[0]
        if 1 < len(self._buffer):
            buf = ''.join(self._buffer)

        data = buf[:size]
        buf = buf[len(data):]
        if buf:
            self._buffer = [buf]
        else:
            self._buffer = []
        return data

    def _fillbuffer(self):
        """read data to the buffer"""
        data = os.read(self._input.fileno(), _chunksize)
        if not data:
            self._eof = True
        else:
            # inefficient add
            self._buffer.append(data)

def popen2(cmd, env=None, newlines=False):
    # Setting bufsize to -1 lets the system decide the buffer size.
    # The default for bufsize is 0, meaning unbuffered. This leads to
    # poor performance on Mac OS X: http://bugs.python.org/issue4194
    p = subprocess.Popen(cmd, shell=True, bufsize=-1,