kafka: Remove Producer singleton

This producer singleton works only if one transport use kafka.

If multiple transports with kafka are used, their overrides each other
the producer on each send.

This change creates only one producer per connection.

A later optimisation can be one producer per driver instance.

Change-Id: I429f7c5efcb41690dd1b17f856bda2425c788e53

oslo_messaging/_drivers/impl_kafka.py

@@ -115,35 +115,6 @@ def with_reconnect(retries=None):
     return decorator
 
 
-class Producer(object):
-    _producer = None
-    _servers = None
-    _lock = threading.Lock()
-
-    @staticmethod
-    @with_reconnect()
-    def connect(servers, **kwargs):
-        return kafka.KafkaProducer(
-            bootstrap_servers=servers,
-            selector=KAFKA_SELECTOR,
-            **kwargs)
-
-    @classmethod
-    def producer(cls, servers, **kwargs):
-        with cls._lock:
-            if not cls._producer or cls._servers != servers:
-                cls._servers = servers
-                cls._producer = cls.connect(servers, **kwargs)
-        return cls._producer
-
-    @classmethod
-    def cleanup(cls):
-        with cls._lock:
-            if cls._producer:
-                cls._producer.close()
-            cls._producer = None
-
-
 class Connection(object):
 
     def __init__(self, conf, url, purpose):
@@ -154,6 +125,7 @@ class Connection(object):
         self.linger_ms = driver_conf.producer_batch_timeout * 1000
         self.conf = conf
         self.producer = None
+        self.producer_lock = threading.Lock()
         self.consumer = None
         self.consumer_timeout = float(driver_conf.kafka_consumer_timeout)
         self.max_fetch_bytes = driver_conf.kafka_max_fetch_bytes
@@ -189,25 +161,24 @@ class Connection(object):
         :param msg: messages for publishing
         :param retry: the number of retry
         """
-
-        message = pack_message(ctxt, msg)
-        self._ensure_connection()
-        self._send_and_retry(message, topic, retry)
-
-    def _send_and_retry(self, message, topic, retry):
-        if not isinstance(message, str):
-            message = jsonutils.dumps(message)
         retry = retry if retry >= 0 else None
+        message = pack_message(ctxt, msg)
+        message = jsonutils.dumps(message)
 
         @with_reconnect(retries=retry)
-        def _send(topic, message):
+        def wrapped_with_reconnect():
+            self._ensure_producer()
+            # NOTE(sileht): This returns a future, we can use get()
+            # if we want to block like other driver
             self.producer.send(topic, message)
 
         try:
-            _send(topic, message)
+            wrapped_with_reconnect()
         except Exception:
-            Producer.cleanup()
+            # NOTE(sileht): if something goes wrong close the producer
-            LOG.exception(_LE("Failed to send message"))
+            # connection
+            self._close_producer()
+            raise
 
     @with_reconnect()
     def _poll_messages(self, timeout):
@@ -239,9 +210,7 @@ class Connection(object):
         pass
 
     def close(self):
-        if self.producer:
+        self._close_producer()
-            self.producer.close()
-        self.producer = None
         if self.consumer:
             self.consumer.close()
             self.consumer = None
@@ -257,14 +226,23 @@ class Connection(object):
         """
         self.consumer.commit()
 
-    def _ensure_connection(self):
+    def _close_producer(self):
-        try:
+        with self.producer_lock:
-            self.producer = Producer.producer(self.hostaddrs,
+            if self.producer:
+                self.producer.close()
+                self.producer = None
+
+    def _ensure_producer(self):
+        if self.producer:
+            return
+        with self.producer_lock:
+            if self.producer:
+                return
+            self.producer = kafka.KafkaProducer(
+                bootstrap_servers=self.hostaddrs,
                 linger_ms=self.linger_ms,
-                                              batch_size=self.batch_size)
+                batch_size=self.batch_size,
-        except kafka.errors.KafkaError as e:
+                selector=KAFKA_SELECTOR)
-            LOG.exception(_LE("KafkaProducer could not be initialized: %s"), e)
-            raise
 
     @with_reconnect()
     def declare_topic_consumer(self, topics, group=None):

oslo_messaging/tests/drivers/test_impl_kafka.py

@@ -74,7 +74,6 @@ class TestKafkaDriver(test_utils.BaseTestCase):
         self.messaging_conf.transport_driver = 'kafka'
         transport = oslo_messaging.get_transport(self.conf)
         self.driver = transport._driver
-        self.addCleanup(kafka_driver.Producer.cleanup)
 
     def test_send(self):
         target = oslo_messaging.Target(topic="topic_test")
@@ -87,7 +86,9 @@ class TestKafkaDriver(test_utils.BaseTestCase):
         with mock.patch("kafka.KafkaProducer") as fake_producer_class:
             fake_producer = fake_producer_class.return_value
             fake_producer.send.side_effect = kafka.errors.NoBrokersAvailable
-            self.driver.send_notification(target, {}, {"payload": ["test_1"]},
+            self.assertRaises(kafka.errors.NoBrokersAvailable,
+                              self.driver.send_notification,
+                              target, {}, {"payload": ["test_1"]},
                               None, retry=3)
             self.assertEqual(3, fake_producer.send.call_count)
 
@@ -127,10 +128,11 @@ class TestKafkaConnection(test_utils.BaseTestCase):
         transport = oslo_messaging.get_transport(self.conf)
         self.driver = transport._driver
 
-    @mock.patch.object(kafka_driver.Connection, '_ensure_connection')
+    def test_notify(self):
-    @mock.patch.object(kafka_driver.Connection, '_send_and_retry')
-    def test_notify(self, fake_send, fake_ensure_connection):
         conn = self.driver._get_connection(common_driver.PURPOSE_SEND)
+
+        with mock.patch("kafka.KafkaProducer") as fake_producer_class:
+            fake_producer = fake_producer_class.return_value
             conn.notify_send("fake_topic", {"fake_ctxt": "fake_param"},
                              {"fake_text": "fake_message_1"}, 10)
-        self.assertEqual(1, len(fake_send.mock_calls))
+            self.assertEqual(1, len(fake_producer.send.mock_calls))