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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
from __future__ import absolute_import
import collections
import logging
import kafka.errors as Errors
from kafka.protocol.api import RequestHeader
from kafka.protocol.commit import GroupCoordinatorResponse
from kafka.protocol.frame import KafkaBytes
from kafka.protocol.types import Int32
from kafka.version import __version__
log = logging.getLogger(__name__)
class KafkaProtocol(object):
"""Manage the kafka network protocol
Use an instance of KafkaProtocol to manage bytes send/recv'd
from a network socket to a broker.
Arguments:
client_id (str): identifier string to be included in each request
api_version (tuple): Optional tuple to specify api_version to use.
Currently only used to check for 0.8.2 protocol quirks, but
may be used for more in the future.
"""
def __init__(self, client_id=None, api_version=None):
if client_id is None:
client_id = self._gen_client_id()
self._client_id = client_id
self._api_version = api_version
self._correlation_id = 0
self._header = KafkaBytes(4)
self._rbuffer = None
self._receiving = False
self.in_flight_requests = collections.deque()
self.bytes_to_send = []
def _next_correlation_id(self):
self._correlation_id = (self._correlation_id + 1) % 2**31
return self._correlation_id
def _gen_client_id(self):
return 'kafka-python' + __version__
def send_request(self, request, correlation_id=None):
"""Encode and queue a kafka api request for sending.
Arguments:
request (object): An un-encoded kafka request.
correlation_id (int, optional): Optionally specify an ID to
correlate requests with responses. If not provided, an ID will
be generated automatically.
Returns:
correlation_id
"""
log.debug('Sending request %s', request)
if correlation_id is None:
correlation_id = self._next_correlation_id()
header = RequestHeader(request,
correlation_id=correlation_id,
client_id=self._client_id)
message = b''.join([header.encode(), request.encode()])
size = Int32.encode(len(message))
data = size + message
self.bytes_to_send.append(data)
if request.expect_response():
ifr = (correlation_id, request)
self.in_flight_requests.append(ifr)
return correlation_id
def send_bytes(self):
"""Retrieve all pending bytes to send on the network"""
data = b''.join(self.bytes_to_send)
self.bytes_to_send = []
return data
def receive_bytes(self, data):
"""Process bytes received from the network.
Arguments:
data (bytes): any length bytes received from a network connection
to a kafka broker.
Returns:
responses (list of (correlation_id, response)): any/all completed
responses, decoded from bytes to python objects.
Raises:
KafkaProtocolError: if the bytes received could not be decoded.
CorrelationIdError: if the response does not match the request
correlation id.
"""
i = 0
n = len(data)
responses = []
while i < n:
# Not receiving is the state of reading the payload header
if not self._receiving:
bytes_to_read = min(4 - self._header.tell(), n - i)
self._header.write(data[i:i+bytes_to_read])
i += bytes_to_read
if self._header.tell() == 4:
self._header.seek(0)
nbytes = Int32.decode(self._header)
# reset buffer and switch state to receiving payload bytes
self._rbuffer = KafkaBytes(nbytes)
self._receiving = True
elif self._header.tell() > 4:
raise Errors.KafkaError('this should not happen - are you threading?')
if self._receiving:
total_bytes = len(self._rbuffer)
staged_bytes = self._rbuffer.tell()
bytes_to_read = min(total_bytes - staged_bytes, n - i)
self._rbuffer.write(data[i:i+bytes_to_read])
i += bytes_to_read
staged_bytes = self._rbuffer.tell()
if staged_bytes > total_bytes:
raise Errors.KafkaError('Receive buffer has more bytes than expected?')
if staged_bytes != total_bytes:
break
self._receiving = False
self._rbuffer.seek(0)
resp = self._process_response(self._rbuffer)
responses.append(resp)
self._reset_buffer()
return responses
def _process_response(self, read_buffer):
recv_correlation_id = Int32.decode(read_buffer)
log.debug('Received correlation id: %d', recv_correlation_id)
if not self.in_flight_requests:
raise Errors.CorrelationIdError(
'No in-flight-request found for server response'
' with correlation ID %d'
% (recv_correlation_id,))
(correlation_id, request) = self.in_flight_requests.popleft()
# 0.8.2 quirk
if (recv_correlation_id == 0 and
correlation_id != 0 and
request.RESPONSE_TYPE is GroupCoordinatorResponse[0] and
(self._api_version == (0, 8, 2) or self._api_version is None)):
log.warning('Kafka 0.8.2 quirk -- GroupCoordinatorResponse'
' Correlation ID does not match request. This'
' should go away once at least one topic has been'
' initialized on the broker.')
elif correlation_id != recv_correlation_id:
# return or raise?
raise Errors.CorrelationIdError(
'Correlation IDs do not match: sent %d, recv %d'
% (correlation_id, recv_correlation_id))
# decode response
log.debug('Processing response %s', request.RESPONSE_TYPE.__name__)
try:
response = request.RESPONSE_TYPE.decode(read_buffer)
except ValueError:
read_buffer.seek(0)
buf = read_buffer.read()
log.error('Response %d [ResponseType: %s Request: %s]:'
' Unable to decode %d-byte buffer: %r',
correlation_id, request.RESPONSE_TYPE,
request, len(buf), buf)
raise Errors.KafkaProtocolError('Unable to decode response')
return (correlation_id, response)
def _reset_buffer(self):
self._receiving = False
self._header.seek(0)
self._rbuffer = None
|
