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# Copyright DataStax, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import unittest
from io import BytesIO
from cassandra import DriverException
from cassandra.segment import Segment, CrcException
from cassandra.connection import segment_codec_no_compression, segment_codec_lz4
def to_bits(b):
return '{:08b}'.format(b)
class SegmentCodecTest(unittest.TestCase):
small_msg = b'b' * 50
max_msg = b'b' * Segment.MAX_PAYLOAD_LENGTH
large_msg = b'b' * (Segment.MAX_PAYLOAD_LENGTH + 1)
@staticmethod
def _header_to_bits(data):
# unpack a header to bits
# data should be the little endian bytes sequence
if len(data) > 6: # compressed
data = data[:5]
bits = ''.join([to_bits(b) for b in reversed(data)])
# return the compressed payload length, the uncompressed payload length,
# the self contained flag and the padding as bits
return bits[23:40] + bits[6:23] + bits[5:6] + bits[:5]
else: # uncompressed
data = data[:3]
bits = ''.join([to_bits(b) for b in reversed(data)])
# return the payload length, the self contained flag and
# the padding as bits
return bits[7:24] + bits[6:7] + bits[:6]
def test_encode_uncompressed_header(self):
buffer = BytesIO()
segment_codec_no_compression.encode_header(buffer, len(self.small_msg), -1, True)
self.assertEqual(buffer.tell(), 6)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
"00000000000110010" + "1" + "000000")
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_encode_compressed_header(self):
buffer = BytesIO()
compressed_length = len(segment_codec_lz4.compress(self.small_msg))
segment_codec_lz4.encode_header(buffer, compressed_length, len(self.small_msg), True)
self.assertEqual(buffer.tell(), 8)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
"{:017b}".format(compressed_length) + "00000000000110010" + "1" + "00000")
def test_encode_uncompressed_header_with_max_payload(self):
buffer = BytesIO()
segment_codec_no_compression.encode_header(buffer, len(self.max_msg), -1, True)
self.assertEqual(buffer.tell(), 6)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
"11111111111111111" + "1" + "000000")
def test_encode_header_fails_if_payload_too_big(self):
buffer = BytesIO()
for codec in [c for c in [segment_codec_no_compression, segment_codec_lz4] if c is not None]:
with self.assertRaises(DriverException):
codec.encode_header(buffer, len(self.large_msg), -1, False)
def test_encode_uncompressed_header_not_self_contained_msg(self):
buffer = BytesIO()
# simulate the first chunk with the max size
segment_codec_no_compression.encode_header(buffer, len(self.max_msg), -1, False)
self.assertEqual(buffer.tell(), 6)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
("11111111111111111"
"0" # not self contained
"000000"))
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_encode_compressed_header_with_max_payload(self):
buffer = BytesIO()
compressed_length = len(segment_codec_lz4.compress(self.max_msg))
segment_codec_lz4.encode_header(buffer, compressed_length, len(self.max_msg), True)
self.assertEqual(buffer.tell(), 8)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
"{:017b}".format(compressed_length) + "11111111111111111" + "1" + "00000")
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_encode_compressed_header_not_self_contained_msg(self):
buffer = BytesIO()
# simulate the first chunk with the max size
compressed_length = len(segment_codec_lz4.compress(self.max_msg))
segment_codec_lz4.encode_header(buffer, compressed_length, len(self.max_msg), False)
self.assertEqual(buffer.tell(), 8)
self.assertEqual(
self._header_to_bits(buffer.getvalue()),
("{:017b}".format(compressed_length) +
"11111111111111111"
"0" # not self contained
"00000"))
def test_decode_uncompressed_header(self):
buffer = BytesIO()
segment_codec_no_compression.encode_header(buffer, len(self.small_msg), -1, True)
buffer.seek(0)
header = segment_codec_no_compression.decode_header(buffer)
self.assertEqual(header.uncompressed_payload_length, -1)
self.assertEqual(header.payload_length, len(self.small_msg))
self.assertEqual(header.is_self_contained, True)
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_decode_compressed_header(self):
buffer = BytesIO()
compressed_length = len(segment_codec_lz4.compress(self.small_msg))
segment_codec_lz4.encode_header(buffer, compressed_length, len(self.small_msg), True)
buffer.seek(0)
header = segment_codec_lz4.decode_header(buffer)
self.assertEqual(header.uncompressed_payload_length, len(self.small_msg))
self.assertEqual(header.payload_length, compressed_length)
self.assertEqual(header.is_self_contained, True)
def test_decode_header_fails_if_corrupted(self):
buffer = BytesIO()
segment_codec_no_compression.encode_header(buffer, len(self.small_msg), -1, True)
# corrupt one byte
buffer.seek(buffer.tell()-1)
buffer.write(b'0')
buffer.seek(0)
with self.assertRaises(CrcException):
segment_codec_no_compression.decode_header(buffer)
def test_decode_uncompressed_self_contained_segment(self):
buffer = BytesIO()
segment_codec_no_compression.encode(buffer, self.small_msg)
buffer.seek(0)
header = segment_codec_no_compression.decode_header(buffer)
segment = segment_codec_no_compression.decode(buffer, header)
self.assertEqual(header.is_self_contained, True)
self.assertEqual(header.uncompressed_payload_length, -1)
self.assertEqual(header.payload_length, len(self.small_msg))
self.assertEqual(segment.payload, self.small_msg)
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_decode_compressed_self_contained_segment(self):
buffer = BytesIO()
segment_codec_lz4.encode(buffer, self.small_msg)
buffer.seek(0)
header = segment_codec_lz4.decode_header(buffer)
segment = segment_codec_lz4.decode(buffer, header)
self.assertEqual(header.is_self_contained, True)
self.assertEqual(header.uncompressed_payload_length, len(self.small_msg))
self.assertGreater(header.uncompressed_payload_length, header.payload_length)
self.assertEqual(segment.payload, self.small_msg)
def test_decode_multi_segments(self):
buffer = BytesIO()
segment_codec_no_compression.encode(buffer, self.large_msg)
buffer.seek(0)
# We should have 2 segments to read
headers = []
segments = []
headers.append(segment_codec_no_compression.decode_header(buffer))
segments.append(segment_codec_no_compression.decode(buffer, headers[0]))
headers.append(segment_codec_no_compression.decode_header(buffer))
segments.append(segment_codec_no_compression.decode(buffer, headers[1]))
self.assertTrue(all([h.is_self_contained is False for h in headers]))
decoded_msg = segments[0].payload + segments[1].payload
self.assertEqual(decoded_msg, self.large_msg)
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_decode_fails_if_corrupted(self):
buffer = BytesIO()
segment_codec_lz4.encode(buffer, self.small_msg)
buffer.seek(buffer.tell()-1)
buffer.write(b'0')
buffer.seek(0)
header = segment_codec_lz4.decode_header(buffer)
with self.assertRaises(CrcException):
segment_codec_lz4.decode(buffer, header)
@unittest.skipUnless(segment_codec_lz4, ' lz4 not installed')
def test_decode_tiny_msg_not_compressed(self):
buffer = BytesIO()
segment_codec_lz4.encode(buffer, b'b')
buffer.seek(0)
header = segment_codec_lz4.decode_header(buffer)
segment = segment_codec_lz4.decode(buffer, header)
self.assertEqual(header.uncompressed_payload_length, 0)
self.assertEqual(header.payload_length, 1)
self.assertEqual(segment.payload, b'b')
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