/usr/lib/python2.7/dist-packages/kafka/codec.py is in python-kafka 0.9.5-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 | import gzip
from io import BytesIO
import struct
from six.moves import xrange
_XERIAL_V1_HEADER = (-126, b'S', b'N', b'A', b'P', b'P', b'Y', 0, 1, 1)
_XERIAL_V1_FORMAT = 'bccccccBii'
try:
import snappy
_HAS_SNAPPY = True
except ImportError:
_HAS_SNAPPY = False
def has_gzip():
return True
def has_snappy():
return _HAS_SNAPPY
def gzip_encode(payload, compresslevel=None):
if not compresslevel:
compresslevel = 9
with BytesIO() as buf:
# Gzip context manager introduced in python 2.6
# so old-fashioned way until we decide to not support 2.6
gzipper = gzip.GzipFile(fileobj=buf, mode="w", compresslevel=compresslevel)
try:
gzipper.write(payload)
finally:
gzipper.close()
result = buf.getvalue()
return result
def gzip_decode(payload):
with BytesIO(payload) as buf:
# Gzip context manager introduced in python 2.6
# so old-fashioned way until we decide to not support 2.6
gzipper = gzip.GzipFile(fileobj=buf, mode='r')
try:
result = gzipper.read()
finally:
gzipper.close()
return result
def snappy_encode(payload, xerial_compatible=False, xerial_blocksize=32 * 1024):
"""Encodes the given data with snappy if xerial_compatible is set then the
stream is encoded in a fashion compatible with the xerial snappy library
The block size (xerial_blocksize) controls how frequent the blocking
occurs 32k is the default in the xerial library.
The format winds up being
+-------------+------------+--------------+------------+--------------+
| Header | Block1 len | Block1 data | Blockn len | Blockn data |
|-------------+------------+--------------+------------+--------------|
| 16 bytes | BE int32 | snappy bytes | BE int32 | snappy bytes |
+-------------+------------+--------------+------------+--------------+
It is important to not that the blocksize is the amount of uncompressed
data presented to snappy at each block, whereas the blocklen is the
number of bytes that will be present in the stream, that is the
length will always be <= blocksize.
"""
if not has_snappy():
raise NotImplementedError("Snappy codec is not available")
if xerial_compatible:
def _chunker():
for i in xrange(0, len(payload), xerial_blocksize):
yield payload[i:i+xerial_blocksize]
out = BytesIO()
header = b''.join([struct.pack('!' + fmt, dat) for fmt, dat
in zip(_XERIAL_V1_FORMAT, _XERIAL_V1_HEADER)])
out.write(header)
for chunk in _chunker():
block = snappy.compress(chunk)
block_size = len(block)
out.write(struct.pack('!i', block_size))
out.write(block)
out.seek(0)
return out.read()
else:
return snappy.compress(payload)
def _detect_xerial_stream(payload):
"""Detects if the data given might have been encoded with the blocking mode
of the xerial snappy library.
This mode writes a magic header of the format:
+--------+--------------+------------+---------+--------+
| Marker | Magic String | Null / Pad | Version | Compat |
|--------+--------------+------------+---------+--------|
| byte | c-string | byte | int32 | int32 |
|--------+--------------+------------+---------+--------|
| -126 | 'SNAPPY' | \0 | | |
+--------+--------------+------------+---------+--------+
The pad appears to be to ensure that SNAPPY is a valid cstring
The version is the version of this format as written by xerial,
in the wild this is currently 1 as such we only support v1.
Compat is there to claim the miniumum supported version that
can read a xerial block stream, presently in the wild this is
1.
"""
if len(payload) > 16:
header = struct.unpack('!' + _XERIAL_V1_FORMAT, bytes(payload)[:16])
return header == _XERIAL_V1_HEADER
return False
def snappy_decode(payload):
if not has_snappy():
raise NotImplementedError("Snappy codec is not available")
if _detect_xerial_stream(payload):
# TODO ? Should become a fileobj ?
out = BytesIO()
byt = payload[16:]
length = len(byt)
cursor = 0
while cursor < length:
block_size = struct.unpack_from('!i', byt[cursor:])[0]
# Skip the block size
cursor += 4
end = cursor + block_size
out.write(snappy.decompress(byt[cursor:end]))
cursor = end
out.seek(0)
return out.read()
else:
return snappy.decompress(payload)
|