156 lines
4.4 KiB
Python
156 lines
4.4 KiB
Python
import copy
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import logging
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import socket
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import struct
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from random import shuffle
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from threading import local
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from kafka.common import ConnectionError
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log = logging.getLogger("kafka")
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DEFAULT_SOCKET_TIMEOUT_SECONDS = 120
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DEFAULT_KAFKA_PORT = 9092
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def collect_hosts(hosts, randomize=True):
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"""
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Collects a comma-separated set of hosts (host:port) and optionally
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randomize the returned list.
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"""
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if isinstance(hosts, basestring):
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hosts = hosts.strip().split(',')
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result = []
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for host_port in hosts:
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res = host_port.split(':')
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host = res[0]
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port = int(res[1]) if len(res) > 1 else DEFAULT_KAFKA_PORT
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result.append((host.strip(), port))
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if randomize:
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shuffle(result)
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return result
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class KafkaConnection(local):
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"""
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A socket connection to a single Kafka broker
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This class is _not_ thread safe. Each call to `send` must be followed
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by a call to `recv` in order to get the correct response. Eventually,
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we can do something in here to facilitate multiplexed requests/responses
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since the Kafka API includes a correlation id.
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host: the host name or IP address of a kafka broker
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port: the port number the kafka broker is listening on
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timeout: default 120. The socket timeout for sending and receiving data
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in seconds. None means no timeout, so a request can block forever.
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"""
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def __init__(self, host, port, timeout=DEFAULT_SOCKET_TIMEOUT_SECONDS):
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super(KafkaConnection, self).__init__()
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self.host = host
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self.port = port
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self.timeout = timeout
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self._sock = None
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self.reinit()
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def __repr__(self):
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return "<KafkaConnection host=%s port=%d>" % (self.host, self.port)
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###################
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# Private API #
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###################
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def _raise_connection_error(self):
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self._dirty = True
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raise ConnectionError("Kafka @ {0}:{1} went away".format(self.host, self.port))
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def _read_bytes(self, num_bytes):
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bytes_left = num_bytes
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responses = []
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log.debug("About to read %d bytes from Kafka", num_bytes)
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if self._dirty:
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self.reinit()
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while bytes_left:
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try:
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data = self._sock.recv(min(bytes_left, 4096))
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except socket.error:
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log.exception('Unable to receive data from Kafka')
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self._raise_connection_error()
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if data == '':
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log.error("Not enough data to read this response")
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self._raise_connection_error()
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bytes_left -= len(data)
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log.debug("Read %d/%d bytes from Kafka", num_bytes - bytes_left, num_bytes)
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responses.append(data)
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return ''.join(responses)
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##################
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# Public API #
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##################
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# TODO multiplex socket communication to allow for multi-threaded clients
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def send(self, request_id, payload):
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"Send a request to Kafka"
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log.debug("About to send %d bytes to Kafka, request %d" % (len(payload), request_id))
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try:
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if self._dirty:
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self.reinit()
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sent = self._sock.sendall(payload)
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if sent is not None:
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self._raise_connection_error()
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except socket.error:
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log.exception('Unable to send payload to Kafka')
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self._raise_connection_error()
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def recv(self, request_id):
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"""
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Get a response from Kafka
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"""
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log.debug("Reading response %d from Kafka" % request_id)
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# Read the size off of the header
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resp = self._read_bytes(4)
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(size,) = struct.unpack('>i', resp)
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# Read the remainder of the response
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resp = self._read_bytes(size)
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return str(resp)
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def copy(self):
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"""
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Create an inactive copy of the connection object
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A reinit() has to be done on the copy before it can be used again
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"""
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c = copy.deepcopy(self)
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c._sock = None
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return c
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def close(self):
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"""
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Close this connection
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"""
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if self._sock:
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self._sock.close()
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def reinit(self):
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"""
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Re-initialize the socket connection
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"""
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self.close()
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self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self._sock.connect((self.host, self.port))
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self._sock.settimeout(self.timeout)
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self._dirty = False
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