[rdkafka] Don't do unnecessary subscribe\unsubscribe on every receive call

pkg/rdkafka/RdKafkaConsumer.php

@@ -82,7 +82,11 @@ public function getQueue()
      */
     public function receive($timeout = 0)
     {
-        $this->consumer->subscribe([$this->topic->getTopicName()]);
+        if (false == $this->subscribed) {
+            $this->consumer->subscribe([$this->topic->getTopicName()]);
+
+            $this->subscribed = true;
+        }
 
         $message = null;
         if ($timeout > 0) {
@@ -95,8 +99,6 @@ public function receive($timeout = 0)
             }
         }
 
-        $this->consumer->unsubscribe();
-
         return $message;
     }
 

pkg/rdkafka/RdKafkaContext.php

@@ -29,12 +29,18 @@ class RdKafkaContext implements PsrContext
      */
     private $producer;
 
+    /**
+     * @var KafkaConsumer[]
+     */
+    private $kafkaConsumers;
+
     /**
      * @param array $config
      */
     public function __construct(array $config)
     {
         $this->config = $config;
+        $this->kafkaConsumers = [];
 
         $this->setSerializer(new JsonSerializer());
     }
@@ -94,8 +100,10 @@ public function createConsumer(PsrDestination $destination)
     {
         InvalidDestinationException::assertDestinationInstanceOf($destination, RdKafkaTopic::class);
 
+        $this->kafkaConsumers[] = $kafkaConsumer = new KafkaConsumer($this->getConf());
+
         $consumer = new RdKafkaConsumer(
-            new KafkaConsumer($this->getConf()),
+            $kafkaConsumer,
             $this,
             $destination,
             $this->getSerializer()
@@ -113,6 +121,12 @@ public function createConsumer(PsrDestination $destination)
      */
     public function close()
     {
+        $kafkaConsumers = $this->kafkaConsumers;
+        $this->kafkaConsumers = [];
+
+        foreach ($kafkaConsumers as $kafkaConsumer) {
+            $kafkaConsumer->unsubscribe();
+        }
     }
 
     /**

pkg/rdkafka/Tests/RdKafkaConsumerTest.php

@@ -59,9 +59,34 @@ public function testShouldReceiveFromQueueAndReturnNullIfNoMessageInQueue()
             ->with(1000)
             ->willReturn($kafkaMessage)
         ;
+
+        $consumer = new RdKafkaConsumer(
+            $kafkaConsumer,
+            $this->createContextMock(),
+            $destination,
+            $this->createSerializerMock()
+        );
+
+        $this->assertNull($consumer->receive(1000));
+    }
+
+    public function testShouldSubscribeOnFirstReceiveOnly()
+    {
+        $destination = new RdKafkaTopic('dest');
+
+        $kafkaMessage = new Message();
+        $kafkaMessage->err = RD_KAFKA_RESP_ERR__TIMED_OUT;
+
+        $kafkaConsumer = $this->createKafkaConsumerMock();
         $kafkaConsumer
             ->expects($this->once())
-            ->method('unsubscribe')
+            ->method('subscribe')
+            ->with(['dest'])
+        ;
+        $kafkaConsumer
+            ->expects($this->any())
+            ->method('consume')
+            ->willReturn($kafkaMessage)
         ;
 
         $consumer = new RdKafkaConsumer(
@@ -71,7 +96,9 @@ public function testShouldReceiveFromQueueAndReturnNullIfNoMessageInQueue()
             $this->createSerializerMock()
         );
 
-        $this->assertNull($consumer->receive(1000));
+        $consumer->receive(1000);
+        $consumer->receive(1000);
+        $consumer->receive(1000);
     }
 
     public function testShouldReceiveFromQueueAndReturnMessageIfMessageInQueue()
@@ -96,10 +123,6 @@ public function testShouldReceiveFromQueueAndReturnMessageIfMessageInQueue()
             ->with(1000)
             ->willReturn($kafkaMessage)
         ;
-        $kafkaConsumer
-            ->expects($this->once())
-            ->method('unsubscribe')
-        ;
 
         $serializer = $this->createSerializerMock();
         $serializer