Method decode_header

cassandra/segment.py:187–207

(self, buffer)

            self._encode_segment(buffer, payload, is_self_contained)

    def decode_header(self, buffer):
        header_data = read_uint_le(buffer, self.header_length)

        expected_header_crc = read_uint_le(buffer, CRC24_LENGTH)
        actual_header_crc = compute_crc24(header_data, self.header_length)
        if actual_header_crc != expected_header_crc:
            raise CrcException('CRC mismatch on header {:x}. Received {:x}", computed {:x}.'.format(
                header_data, expected_header_crc, actual_header_crc))

        payload_length = header_data & Segment.MAX_PAYLOAD_LENGTH
        header_data >>= 17

        if self.compression:
            uncompressed_payload_length = header_data & Segment.MAX_PAYLOAD_LENGTH
            header_data >>= 17
        else:
            uncompressed_payload_length = -1

        is_self_contained = (header_data & 1) == 1

        return SegmentHeader(payload_length, uncompressed_payload_length, is_self_contained)

    def decode(self, buffer, header):
        encoded_payload = buffer.read(header.payload_length)