Improve metadata protocol handling

  - add MetadataRequest and MetadataResponse namedtuples
  - add TopicMetadata namedtuple
  - add error codes to Topic and Partition Metadata
  - add KafkaClient.send_metadata_request() method
  - KafkaProtocol.decode_metadata_response changed
    to return a MetadataResponse object
    so that it is consistent with server api: [broker_list, topic_list]

1 files changed, 33 insertions, 41 deletions

diff --git a/test/test_protocol.py b/test/test_protocol.py
index 2089f48..a92d20e 100644
--- a/test/test_protocol.py
+++ b/test/test_protocol.py
@@ -11,10 +11,10 @@ from kafka.common import (
     OffsetRequest, OffsetCommitRequest, OffsetFetchRequest,
     OffsetResponse, OffsetCommitResponse, OffsetFetchResponse,
     ProduceRequest, FetchRequest, Message, ChecksumError,
-    ConsumerFetchSizeTooSmall, ProduceResponse, FetchResponse, OffsetAndMessage,
-    BrokerMetadata, PartitionMetadata, TopicAndPartition, KafkaUnavailableError,
-    ProtocolError, LeaderUnavailableError, PartitionUnavailableError,
-    UnsupportedCodecError
+    ProduceResponse, FetchResponse, OffsetAndMessage,
+    BrokerMetadata, TopicMetadata, PartitionMetadata, TopicAndPartition,
+    KafkaUnavailableError, PartitionUnavailableError,
+    UnsupportedCodecError, ConsumerFetchSizeTooSmall, ProtocolError,
 )
 from kafka.codec import (
     has_snappy, gzip_encode, gzip_decode,
@@ -454,21 +454,22 @@ class TestProtocol(unittest2.TestCase):
 
         self.assertEqual(encoded, expected)
 
-    def _create_encoded_metadata_response(self, broker_data, topic_data,
-                                          topic_errors, partition_errors):
-        encoded = struct.pack('>ii', 3, len(broker_data))
-        for node_id, broker in broker_data.iteritems():
-            encoded += struct.pack('>ih%dsi' % len(broker.host), node_id,
+    def _create_encoded_metadata_response(self, brokers, topics):
+        encoded = struct.pack('>ii', 3, len(brokers))
+        for broker in brokers:
+            encoded += struct.pack('>ih%dsi' % len(broker.host), broker.nodeId,
                                    len(broker.host), broker.host, broker.port)
 
-        encoded += struct.pack('>i', len(topic_data))
-        for topic, partitions in topic_data.iteritems():
-            encoded += struct.pack('>hh%dsi' % len(topic), topic_errors[topic],
-                                   len(topic), topic, len(partitions))
-            for partition, metadata in partitions.iteritems():
+        encoded += struct.pack('>i', len(topics))
+        for topic in topics:
+            encoded += struct.pack('>hh%dsi' % len(topic.topic),
+                                   topic.error, len(topic.topic),
+                                   topic.topic, len(topic.partitions))
+            for metadata in topic.partitions:
                 encoded += struct.pack('>hiii',
-                                       partition_errors[(topic, partition)],
-                                       partition, metadata.leader,
+                                       metadata.error,
+                                       metadata.partition,
+                                       metadata.leader,
                                        len(metadata.replicas))
                 if len(metadata.replicas) > 0:
                     encoded += struct.pack('>%di' % len(metadata.replicas),
@@ -478,35 +479,26 @@ class TestProtocol(unittest2.TestCase):
                 if len(metadata.isr) > 0:
                     encoded += struct.pack('>%di' % len(metadata.isr),
                                            *metadata.isr)
-
         return encoded
 
     def test_decode_metadata_response(self):
-        node_brokers = {
-            0: BrokerMetadata(0, "brokers1.kafka.rdio.com", 1000),
-            1: BrokerMetadata(1, "brokers1.kafka.rdio.com", 1001),
-            3: BrokerMetadata(3, "brokers2.kafka.rdio.com", 1000)
-        }
-
-        topic_partitions = {
-            "topic1": {
-                0: PartitionMetadata("topic1", 0, 1, (0, 2), (2,)),
-                1: PartitionMetadata("topic1", 1, 3, (0, 1), (0, 1))
-            },
-            "topic2": {
-                0: PartitionMetadata("topic2", 0, 0, (), ())
-            }
-        }
-        topic_errors = {"topic1": 0, "topic2": 1}
-        partition_errors = {
-            ("topic1", 0): 0,
-            ("topic1", 1): 1,
-            ("topic2", 0): 0
-        }
+        node_brokers = [
+            BrokerMetadata(0, "brokers1.kafka.rdio.com", 1000),
+            BrokerMetadata(1, "brokers1.kafka.rdio.com", 1001),
+            BrokerMetadata(3, "brokers2.kafka.rdio.com", 1000)
+        ]
+
+        topic_partitions = [
+            TopicMetadata("topic1", 0, [
+                PartitionMetadata("topic1", 0, 1, (0, 2), (2,), 0),
+                PartitionMetadata("topic1", 1, 3, (0, 1), (0, 1), 1)
+            ]),
+            TopicMetadata("topic2", 1, [
+                PartitionMetadata("topic2", 0, 0, (), (), 0),
+            ]),
+        ]
         encoded = self._create_encoded_metadata_response(node_brokers,
-                                                         topic_partitions,
-                                                         topic_errors,
-                                                         partition_errors)
+                                                         topic_partitions)
         decoded = KafkaProtocol.decode_metadata_response(encoded)
         self.assertEqual(decoded, (node_brokers, topic_partitions))