comparison mercurial/util.py @ 44035:8ed8dfbeabb9

mmap: add a size argument to mmapread

With this argument, we can control the size of the mmap created. (previously it
was always the whole file.

Differential Revision: https://phab.mercurial-scm.org/D7808

44034:ab595920de0e

            self._buffer.append(data)

        return data


def mmapread(fp):
    try:
        fd = getattr(fp, 'fileno', lambda: fp)()
        return mmap.mmap(fd, 0, access=mmap.ACCESS_READ)
    except ValueError:
        # Empty files cannot be mmapped, but mmapread should still work.  Check
        # if the file is empty, and if so, return an empty buffer.
        if os.fstat(fd).st_size == 0:
            return b''

44035:8ed8dfbeabb9

            self._buffer.append(data)

        return data


def mmapread(fp, size=None):
    if size == 0:
        # size of 0 to mmap.mmap() means "all data"
        # rather than "zero bytes", so special case that.
        return b''
    elif size is None:
        size = 0
    try:
        fd = getattr(fp, 'fileno', lambda: fp)()
        return mmap.mmap(fd, size, access=mmap.ACCESS_READ)
    except ValueError:
        # Empty files cannot be mmapped, but mmapread should still work.  Check
        # if the file is empty, and if so, return an empty buffer.
        if os.fstat(fd).st_size == 0:
            return b''