Merge pull request #403 from dpkp/client_request_response_ordering

Client request response ordering

kafka/client.py

@@ -138,7 +138,8 @@ class KafkaClient(object):
         Arguments:
 
         payloads: list of object-like entities with a topic (str) and
-            partition (int) attribute
+            partition (int) attribute; payloads with duplicate topic-partitions
+            are not supported.
 
         encode_fn: a method to encode the list of payloads to a request body,
             must accept client_id, correlation_id, and payloads as
@@ -152,6 +153,10 @@ class KafkaClient(object):
 
         List of response objects in the same order as the supplied payloads
         """
+        # encoders / decoders do not maintain ordering currently
+        # so we need to keep this so we can rebuild order before returning
+        original_ordering = [(p.topic, p.partition) for p in payloads]
+
         # Group the requests by topic+partition
         brokers_for_payloads = []
         payloads_by_broker = collections.defaultdict(list)
@@ -165,7 +170,7 @@ class KafkaClient(object):
 
         # For each broker, send the list of request payloads
         # and collect the responses and errors
-        responses_by_broker = collections.defaultdict(list)
+        responses = {}
         broker_failures = []
         for broker, payloads in payloads_by_broker.items():
             requestId = self._next_id()
@@ -184,7 +189,8 @@ class KafkaClient(object):
                             'to server %s: %s', requestId, broker, e)
 
                 for payload in payloads:
-                    responses_by_broker[broker].append(FailedPayloadsError(payload))
+                    topic_partition = (payload.topic, payload.partition)
+                    responses[topic_partition] = FailedPayloadsError(payload)
 
             # No exception, try to get response
             else:
@@ -196,7 +202,8 @@ class KafkaClient(object):
                     log.debug('Request %s does not expect a response '
                               '(skipping conn.recv)', requestId)
                     for payload in payloads:
-                        responses_by_broker[broker].append(None)
+                        topic_partition = (payload.topic, payload.partition)
+                        responses[topic_partition] = None
                     continue
 
                 try:
@@ -208,12 +215,17 @@ class KafkaClient(object):
                                 requestId, broker, e)
 
                     for payload in payloads:
-                        responses_by_broker[broker].append(FailedPayloadsError(payload))
+                        topic_partition = (payload.topic, payload.partition)
+                        responses[topic_partition] = FailedPayloadsError(payload)
 
                 else:
+                    _resps = []
                     for payload_response in decoder_fn(response):
-                        responses_by_broker[broker].append(payload_response)
-                    log.debug('Response %s: %s', requestId, responses_by_broker[broker])
+                        topic_partition = (payload_response.topic,
+                                           payload_response.partition)
+                        responses[topic_partition] = payload_response
+                        _resps.append(payload_response)
+                    log.debug('Response %s: %s', requestId, _resps)
 
         # Connection errors generally mean stale metadata
         # although sometimes it means incorrect api request
@@ -223,9 +235,7 @@ class KafkaClient(object):
             self.reset_all_metadata()
 
         # Return responses in the same order as provided
-        responses_by_payload = [responses_by_broker[broker].pop(0)
-                                for broker in brokers_for_payloads]
-        return responses_by_payload
+        return [responses[tp] for tp in original_ordering]
 
     def __repr__(self):
         return '<KafkaClient client_id=%s>' % (self.client_id)

test/test_client_integration.py

@@ -2,8 +2,9 @@ import os
 
 from kafka.common import (
     FetchRequest, OffsetCommitRequest, OffsetFetchRequest,
-    KafkaTimeoutError
+    KafkaTimeoutError, ProduceRequest
 )
+from kafka.protocol import create_message
 
 from test.fixtures import ZookeeperFixture, KafkaFixture
 from test.testutil import KafkaIntegrationTestCase, kafka_versions
@@ -49,6 +50,35 @@ class TestKafkaClientIntegration(KafkaIntegrationTestCase):
         with self.assertRaises(KafkaTimeoutError):
             self.client.ensure_topic_exists(b"this_topic_doesnt_exist", timeout=0)
 
+    @kafka_versions('all')
+    def test_send_produce_request_maintains_request_response_order(self):
+
+        self.client.ensure_topic_exists(b'foo', timeout=1)
+        self.client.ensure_topic_exists(b'bar', timeout=1)
+
+        requests = [
+            ProduceRequest(
+                b'foo', 0,
+                [create_message(b'a'), create_message(b'b')]),
+            ProduceRequest(
+                b'bar', 1,
+                [create_message(b'a'), create_message(b'b')]),
+            ProduceRequest(
+                b'foo', 1,
+                [create_message(b'a'), create_message(b'b')]),
+            ProduceRequest(
+                b'bar', 0,
+                [create_message(b'a'), create_message(b'b')]),
+        ]
+
+        responses = self.client.send_produce_request(requests)
+        while len(responses):
+            request = requests.pop()
+            response = responses.pop()
+            self.assertEqual(request.topic, response.topic)
+            self.assertEqual(request.partition, response.partition)
+
+
     ####################
     #   Offset Tests   #
     ####################