def read_block()

in azure/datalake/store/core.py [0:0]

• 11 lines of code
• 4 McCabe index (conditional complexity)

    def read_block(self, fn, offset, length, delimiter=None):
        """ Read a block of bytes from an ADL file

        Starting at ``offset`` of the file, read ``length`` bytes.  If
        ``delimiter`` is set then we ensure that the read starts and stops at
        delimiter boundaries that follow the locations ``offset`` and ``offset
        + length``.  If ``offset`` is zero then we start at zero.  The
        bytestring returned WILL include the end delimiter string.

        If offset+length is beyond the eof, reads to eof.

        Parameters
        ----------
        fn: string
            Path to filename on ADL
        offset: int
            Byte offset to start read
        length: int
            Number of bytes to read
        delimiter: bytes (optional)
            Ensure reading starts and stops at delimiter bytestring

        Examples
        --------
        >>> adl.read_block('data/file.csv', 0, 13)  # doctest: +SKIP
        b'Alice, 100\\nBo'
        >>> adl.read_block('data/file.csv', 0, 13, delimiter=b'\\n')  # doctest: +SKIP
        b'Alice, 100\\nBob, 200\\n'

        Use ``length=None`` to read to the end of the file.
        >>> adl.read_block('data/file.csv', 0, None, delimiter=b'\\n')  # doctest: +SKIP
        b'Alice, 100\\nBob, 200\\nCharlie, 300'

        See Also
        --------
        distributed.utils.read_block
        """
        with self.open(fn, 'rb') as f:
            size = f.info()['length']
            if offset >= size:
                return b''
            if length is None:
                length = size
            if offset + length > size:
                length = size - offset
            bytes = read_block(f, offset, length, delimiter)
        return bytes