369 lines
13 KiB
Python
369 lines
13 KiB
Python
import copy
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import logging
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from collections import defaultdict
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from functools import partial
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from itertools import count
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from kafka.common import (ErrorMapping, TopicAndPartition,
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ConnectionError, FailedPayloadsError,
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BrokerResponseError, PartitionUnavailableError,
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KafkaUnavailableError, KafkaRequestError)
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from kafka.conn import KafkaConnection
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from kafka.protocol import KafkaProtocol
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log = logging.getLogger("kafka")
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class KafkaClient(object):
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CLIENT_ID = "kafka-python"
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ID_GEN = count()
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def __init__(self, host, port, client_id=CLIENT_ID, timeout=10):
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# We need one connection to bootstrap
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self.client_id = client_id
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self.timeout = timeout
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self.conns = { # (host, port) -> KafkaConnection
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(host, port): KafkaConnection(host, port, timeout=timeout)
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}
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self.brokers = {} # broker_id -> BrokerMetadata
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self.topics_to_brokers = {} # topic_id -> broker_id
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self.topic_partitions = {} # topic_id -> [0, 1, 2, ...]
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self.load_metadata_for_topics() # bootstrap with all metadata
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##################
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# Private API #
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##################
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def _get_conn_for_broker(self, broker):
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"""
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Get or create a connection to a broker
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"""
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if (broker.host, broker.port) not in self.conns:
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self.conns[(broker.host, broker.port)] = \
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KafkaConnection(broker.host, broker.port, timeout=self.timeout)
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return self.conns[(broker.host, broker.port)]
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def _get_leader_for_partition(self, topic, partition):
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key = TopicAndPartition(topic, partition)
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if key not in self.topics_to_brokers:
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self.load_metadata_for_topics(topic)
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if key not in self.topics_to_brokers:
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raise KafkaRequestError("Partition does not exist: %s" % str(key))
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return self.topics_to_brokers[key]
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def _next_id(self):
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"""
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Generate a new correlation id
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"""
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return KafkaClient.ID_GEN.next()
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def _send_broker_unaware_request(self, requestId, request):
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"""
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Attempt to send a broker-agnostic request to one of the available
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brokers. Keep trying until you succeed.
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"""
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for conn in self.conns.values():
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try:
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conn.send(requestId, request)
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response = conn.recv(requestId)
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return response
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except Exception, e:
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log.warning("Could not send request [%r] to server %s, "
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"trying next server: %s" % (request, conn, e))
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continue
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raise KafkaUnavailableError("All servers failed to process request")
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def _send_broker_aware_request(self, payloads, encoder_fn, decoder_fn):
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"""
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Group a list of request payloads by topic+partition and send them to
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the leader broker for that partition using the supplied encode/decode
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functions
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Params
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======
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payloads: list of object-like entities with a topic and
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partition attribute
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encode_fn: a method to encode the list of payloads to a request body,
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must accept client_id, correlation_id, and payloads as
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keyword arguments
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decode_fn: a method to decode a response body into response objects.
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The response objects must be object-like and have topic
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and partition attributes
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Return
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======
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List of response objects in the same order as the supplied payloads
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"""
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# Group the requests by topic+partition
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original_keys = []
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payloads_by_broker = defaultdict(list)
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for payload in payloads:
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leader = self._get_leader_for_partition(payload.topic,
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payload.partition)
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if leader == -1:
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raise PartitionUnavailableError("Leader is unassigned for %s-%s" % payload.topic, payload.partition)
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payloads_by_broker[leader].append(payload)
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original_keys.append((payload.topic, payload.partition))
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# Accumulate the responses in a dictionary
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acc = {}
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# keep a list of payloads that were failed to be sent to brokers
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failed_payloads = []
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# For each broker, send the list of request payloads
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for broker, payloads in payloads_by_broker.items():
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conn = self._get_conn_for_broker(broker)
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requestId = self._next_id()
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request = encoder_fn(client_id=self.client_id,
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correlation_id=requestId, payloads=payloads)
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failed = False
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# Send the request, recv the response
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try:
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conn.send(requestId, request)
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if decoder_fn is None:
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continue
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try:
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response = conn.recv(requestId)
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except ConnectionError, e:
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log.warning("Could not receive response to request [%s] "
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"from server %s: %s", request, conn, e)
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failed = True
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except ConnectionError, e:
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log.warning("Could not send request [%s] to server %s: %s",
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request, conn, e)
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failed = True
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if failed:
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failed_payloads += payloads
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self.reset_all_metadata()
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continue
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for response in decoder_fn(response):
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acc[(response.topic, response.partition)] = response
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if failed_payloads:
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raise FailedPayloadsError(failed_payloads)
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# Order the accumulated responses by the original key order
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return (acc[k] for k in original_keys) if acc else ()
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def _raise_on_response_error(self, resp):
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if resp.error == ErrorMapping.NO_ERROR:
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return
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if resp.error in (ErrorMapping.UNKNOWN_TOPIC_OR_PARTITON,
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ErrorMapping.NOT_LEADER_FOR_PARTITION):
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self.reset_topic_metadata(resp.topic)
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raise BrokerResponseError(
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"Request for %s failed with errorcode=%d" %
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(TopicAndPartition(resp.topic, resp.partition), resp.error))
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#################
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# Public API #
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#################
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def reset_topic_metadata(self, *topics):
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for topic in topics:
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try:
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partitions = self.topic_partitions[topic]
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except KeyError:
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continue
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for partition in partitions:
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self.topics_to_brokers.pop(TopicAndPartition(topic, partition), None)
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del self.topic_partitions[topic]
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def reset_all_metadata(self):
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self.topics_to_brokers.clear()
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self.topic_partitions.clear()
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def has_metadata_for_topic(self, topic):
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return topic in self.topic_partitions
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def close(self):
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for conn in self.conns.values():
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conn.close()
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def copy(self):
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"""
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Create an inactive copy of the client 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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for k, v in c.conns.items():
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c.conns[k] = v.copy()
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return c
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def reinit(self):
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for conn in self.conns.values():
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conn.reinit()
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def load_metadata_for_topics(self, *topics):
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"""
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Discover brokers and metadata for a set of topics. This function is called
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lazily whenever metadata is unavailable.
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"""
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request_id = self._next_id()
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request = KafkaProtocol.encode_metadata_request(self.client_id,
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request_id, topics)
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response = self._send_broker_unaware_request(request_id, request)
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(brokers, topics) = KafkaProtocol.decode_metadata_response(response)
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log.debug("Broker metadata: %s", brokers)
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log.debug("Topic metadata: %s", topics)
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self.brokers = brokers
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for topic, partitions in topics.items():
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self.reset_topic_metadata(topic)
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if not partitions:
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continue
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self.topic_partitions[topic] = []
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for partition, meta in partitions.items():
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topic_part = TopicAndPartition(topic, partition)
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self.topics_to_brokers[topic_part] = brokers[meta.leader]
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self.topic_partitions[topic].append(partition)
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def send_produce_request(self, payloads=[], acks=1, timeout=1000,
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fail_on_error=True, callback=None):
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"""
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Encode and send some ProduceRequests
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ProduceRequests will be grouped by (topic, partition) and then
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sent to a specific broker. Output is a list of responses in the
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same order as the list of payloads specified
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Params
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======
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payloads: list of ProduceRequest
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fail_on_error: boolean, should we raise an Exception if we
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encounter an API error?
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callback: function, instead of returning the ProduceResponse,
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first pass it through this function
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Return
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======
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list of ProduceResponse or callback(ProduceResponse), in the
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order of input payloads
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"""
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encoder = partial(
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KafkaProtocol.encode_produce_request,
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acks=acks,
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timeout=timeout)
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if acks == 0:
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decoder = None
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else:
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decoder = KafkaProtocol.decode_produce_response
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resps = self._send_broker_aware_request(payloads, encoder, decoder)
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out = []
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for resp in resps:
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if fail_on_error is True:
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self._raise_on_response_error(resp)
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if callback is not None:
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out.append(callback(resp))
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else:
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out.append(resp)
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return out
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def send_fetch_request(self, payloads=[], fail_on_error=True,
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callback=None, max_wait_time=100, min_bytes=4096):
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"""
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Encode and send a FetchRequest
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Payloads are grouped by topic and partition so they can be pipelined
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to the same brokers.
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"""
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encoder = partial(KafkaProtocol.encode_fetch_request,
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max_wait_time=max_wait_time,
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min_bytes=min_bytes)
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resps = self._send_broker_aware_request(
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payloads, encoder,
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KafkaProtocol.decode_fetch_response)
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out = []
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for resp in resps:
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if fail_on_error is True:
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self._raise_on_response_error(resp)
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if callback is not None:
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out.append(callback(resp))
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else:
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out.append(resp)
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return out
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def send_offset_request(self, payloads=[], fail_on_error=True,
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callback=None):
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resps = self._send_broker_aware_request(
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payloads,
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KafkaProtocol.encode_offset_request,
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KafkaProtocol.decode_offset_response)
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out = []
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for resp in resps:
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if fail_on_error is True:
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self._raise_on_response_error(resp)
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if callback is not None:
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out.append(callback(resp))
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else:
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out.append(resp)
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return out
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def send_offset_commit_request(self, group, payloads=[],
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fail_on_error=True, callback=None):
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encoder = partial(KafkaProtocol.encode_offset_commit_request,
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group=group)
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decoder = KafkaProtocol.decode_offset_commit_response
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resps = self._send_broker_aware_request(payloads, encoder, decoder)
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out = []
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for resp in resps:
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if fail_on_error is True:
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self._raise_on_response_error(resp)
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if callback is not None:
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out.append(callback(resp))
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else:
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out.append(resp)
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return out
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def send_offset_fetch_request(self, group, payloads=[],
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fail_on_error=True, callback=None):
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encoder = partial(KafkaProtocol.encode_offset_fetch_request,
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group=group)
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decoder = KafkaProtocol.decode_offset_fetch_response
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resps = self._send_broker_aware_request(payloads, encoder, decoder)
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out = []
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for resp in resps:
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if fail_on_error is True:
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self._raise_on_response_error(resp)
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if callback is not None:
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out.append(callback(resp))
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else:
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out.append(resp)
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return out
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