Use standard exceptions in client._get_leader_for_partition()

- drop custom PartitionUnavailable exception
- raise UnknownTopicOrPartitionError or LeaderNotAvailableError
- add tests for exception raises

kafka/client.py

@@ -8,9 +8,9 @@ import kafka.common
 
 from kafka.common import (TopicAndPartition, BrokerMetadata,
                           ConnectionError, FailedPayloadsError,
-                          PartitionUnavailableError, LeaderNotAvailableError,
-                          KafkaUnavailableError, KafkaTimeoutError,
-                          UnknownTopicOrPartitionError, NotLeaderForPartitionError)
+                          KafkaTimeoutError, KafkaUnavailableError,
+                          LeaderNotAvailableError, UnknownTopicOrPartitionError,
+                          NotLeaderForPartitionError)
 
 from kafka.conn import collect_hosts, KafkaConnection, DEFAULT_SOCKET_TIMEOUT_SECONDS
 from kafka.protocol import KafkaProtocol
@@ -63,20 +63,37 @@ class KafkaClient(object):
         Returns the leader for a partition or None if the partition exists
         but has no leader.
 
-        PartitionUnavailableError will be raised if the topic or partition
+        UnknownTopicOrPartitionError will be raised if the topic or partition
         is not part of the metadata.
+
+        LeaderNotAvailableError is raised if server has metadata, but there is
+        no current leader
         """
 
         key = TopicAndPartition(topic, partition)
-        # reload metadata whether the partition is not available
-        # or has no leader (broker is None)
-        if self.topics_to_brokers.get(key) is None:
-            self.load_metadata_for_topics(topic)
 
-        if key not in self.topics_to_brokers:
-            raise PartitionUnavailableError("%s not available" % str(key))
+        # Use cached metadata if it is there
+        if self.topics_to_brokers.get(key) is not None:
+            return self.topics_to_brokers[key]
 
-        return self.topics_to_brokers[key]
+        # Otherwise refresh metadata
+
+        # If topic does not already exist, this will raise
+        # UnknownTopicOrPartitionError if not auto-creating
+        # LeaderNotAvailableError otherwise until partitions are created
+        self.load_metadata_for_topics(topic)
+
+        # If the partition doesn't actually exist, raise
+        if partition not in self.topic_partitions[topic]:
+            raise UnknownTopicOrPartitionError(key)
+
+        # If there's no leader for the partition, raise
+        meta = self.topic_partitions[topic][partition]
+        if meta.leader == -1:
+            raise LeaderNotAvailableError(meta)
+
+        # Otherwise return the BrokerMetadata
+        return self.brokers[meta.leader]
 
     def _next_id(self):
         """
@@ -136,10 +153,6 @@ class KafkaClient(object):
         for payload in payloads:
             leader = self._get_leader_for_partition(payload.topic,
                                                     payload.partition)
-            if leader is None:
-                raise LeaderNotAvailableError(
-                    "Leader not available for topic %s partition %s" %
-                    (payload.topic, payload.partition))
 
             payloads_by_broker[leader].append(payload)
             original_keys.append((payload.topic, payload.partition))

kafka/common.py

@@ -158,10 +158,6 @@ class KafkaTimeoutError(KafkaError):
     pass
 
 
-class PartitionUnavailableError(KafkaError):
-    pass
-
-
 class FailedPayloadsError(KafkaError):
     pass
 

test/test_client.py

@@ -7,7 +7,7 @@ from kafka.common import (
     ProduceRequest, MetadataResponse,
     BrokerMetadata, TopicMetadata, PartitionMetadata,
     TopicAndPartition, KafkaUnavailableError,
-    LeaderNotAvailableError, PartitionUnavailableError, NoError,
+    LeaderNotAvailableError, NoError,
     UnknownTopicOrPartitionError
 )
 from kafka.protocol import create_message
@@ -191,7 +191,6 @@ class TestKafkaClient(unittest2.TestCase):
     @patch('kafka.client.KafkaConnection')
     @patch('kafka.client.KafkaProtocol')
     def test_get_leader_for_unassigned_partitions(self, protocol, conn):
-        "Get leader raises if no partitions is defined for a topic"
 
         conn.recv.return_value = 'response'  # anything but None
 
@@ -201,7 +200,8 @@ class TestKafkaClient(unittest2.TestCase):
         ]
 
         topics = [
-            TopicMetadata('topic_no_partitions', NO_ERROR, [])
+            TopicMetadata('topic_no_partitions', NO_LEADER, []),
+            TopicMetadata('topic_unknown', UNKNOWN_TOPIC_OR_PARTITION, []),
         ]
         protocol.decode_metadata_response.return_value = MetadataResponse(brokers, topics)
 
@@ -209,13 +209,15 @@ class TestKafkaClient(unittest2.TestCase):
 
         self.assertDictEqual({}, client.topics_to_brokers)
 
-        with self.assertRaises(PartitionUnavailableError):
+        with self.assertRaises(LeaderNotAvailableError):
             client._get_leader_for_partition('topic_no_partitions', 0)
 
+        with self.assertRaises(UnknownTopicOrPartitionError):
+            client._get_leader_for_partition('topic_unknown', 0)
+
     @patch('kafka.client.KafkaConnection')
     @patch('kafka.client.KafkaProtocol')
-    def test_get_leader_returns_none_when_noleader(self, protocol, conn):
-        "Getting leader for partitions returns None when the partiion has no leader"
+    def test_get_leader_exceptions_when_noleader(self, protocol, conn):
 
         conn.recv.return_value = 'response'  # anything but None
 
@@ -241,8 +243,16 @@ class TestKafkaClient(unittest2.TestCase):
                 TopicAndPartition('topic_noleader', 1): None
             },
             client.topics_to_brokers)
-        self.assertIsNone(client._get_leader_for_partition('topic_noleader', 0))
-        self.assertIsNone(client._get_leader_for_partition('topic_noleader', 1))
+
+        # No leader partitions -- raise LeaderNotAvailableError
+        with self.assertRaises(LeaderNotAvailableError):
+            self.assertIsNone(client._get_leader_for_partition('topic_noleader', 0))
+        with self.assertRaises(LeaderNotAvailableError):
+            self.assertIsNone(client._get_leader_for_partition('topic_noleader', 1))
+
+        # Unknown partitions -- raise UnknownTopicOrPartitionError
+        with self.assertRaises(UnknownTopicOrPartitionError):
+            self.assertIsNone(client._get_leader_for_partition('topic_noleader', 2))
 
         topics = [
             TopicMetadata('topic_noleader', NO_ERROR, [

test/test_consumer.py

@@ -5,15 +5,7 @@ import unittest2
 
 from mock import MagicMock, patch
 
-from kafka import KafkaClient
 from kafka.consumer import SimpleConsumer
-from kafka.common import (
-    ProduceRequest, BrokerMetadata, PartitionMetadata,
-    TopicAndPartition, PartitionUnavailableError
-)
-from kafka.protocol import (
-    create_message, KafkaProtocol
-)
 
 class TestKafkaConsumer(unittest2.TestCase):
     def test_non_integer_partitions(self):

test/test_protocol.py

@@ -13,8 +13,8 @@ from kafka.common import (
     ProduceRequest, FetchRequest, Message, ChecksumError,
     ProduceResponse, FetchResponse, OffsetAndMessage,
     BrokerMetadata, TopicMetadata, PartitionMetadata, TopicAndPartition,
-    KafkaUnavailableError, PartitionUnavailableError,
-    UnsupportedCodecError, ConsumerFetchSizeTooSmall, ProtocolError,
+    KafkaUnavailableError, UnsupportedCodecError, ConsumerFetchSizeTooSmall,
+    ProtocolError
 )
 from kafka.codec import (
     has_snappy, gzip_encode, gzip_decode,