Set commit_async as true by default for Kafka

Provide addition configuration documentation for integrating with Symfony bundle

Fixes #580

Author: Steveb-p

docs/transport/kafka.md

@@ -41,7 +41,7 @@ $connectionFactory = new RdKafkaConnectionFactory('kafka:');
 $connectionFactory = new RdKafkaConnectionFactory([]);
 
 // connect to Kafka broker at example.com:1000 plus custom options
-$connectionFactory = new RdKafkaConnectionFactory([ 
+$connectionFactory = new RdKafkaConnectionFactory([
     'global' => [
         'group.id' => uniqid('', true),
         'metadata.broker.list' => 'example.com:1000',
@@ -54,11 +54,11 @@ $connectionFactory = new RdKafkaConnectionFactory([
 
 $context = $connectionFactory->createContext();
 
-// if you have enqueue/enqueue library installed you can use a factory to build context from DSN 
+// if you have enqueue/enqueue library installed you can use a factory to build context from DSN
 $context = (new \Enqueue\ConnectionFactoryFactory())->create('kafka:')->createContext();
 ```
 
-## Send message to topic 
+## Send message to topic
 
 ```php
 <?php
@@ -71,7 +71,7 @@ $fooTopic = $context->createTopic('foo');
 $context->createProducer()->send($fooTopic, $message);
 ```
 
-## Send message to queue 
+## Send message to queue
 
 ```php
 <?php
@@ -94,7 +94,7 @@ $fooQueue = $context->createQueue('foo');
 
 $consumer = $context->createConsumer($fooQueue);
 
-// Enable async commit to gain better performance. 
+// Enable async commit to gain better performance (true by default since version 0.9.9).
 //$consumer->setCommitAsync(true);
 
 $message = $consumer->receive();
@@ -108,7 +108,7 @@ $consumer->acknowledge($message);
 ## Serialize message
 
 By default the transport serializes messages to json format but you might want to use another format such as [Apache Avro](https://avro.apache.org/docs/1.2.0/).
-For that you have to implement Serializer interface and set it to the context, producer or consumer. 
+For that you have to implement Serializer interface and set it to the context, producer or consumer.
 If a serializer set to context it will be injected to all consumers and producers created by the context.
 
 ```php
@@ -119,7 +119,7 @@ use Enqueue\RdKafka\RdKafkaMessage;
 class FooSerializer implements Serializer
 {
     public function toMessage($string) {}
-    
+
     public function toString(RdKafkaMessage $message) {}
 }
 
@@ -145,4 +145,44 @@ $consumer->setOffset(123);
 $message = $consumer->receive(2000);
 ```
 
-[back to index](index.md)
+## Usage with Symfony bundle
+
+Set your enqueue to use rdkafka as your transport
+
+```yaml
+# app/config/config.yml
+
+enqueue:
+    default:
+        transport: "rdkafka:"
+        client: ~
+```
+
+You can also you extended configuration to pass additional options, if you don't want to pass them via DSN string or
+need to pass specific options. Since rdkafka uses librdkafka (being basically a wrapper around it) most configuration
+options are identical to those found at https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md.
+
+```yaml
+# app/config/config.yml
+
+enqueue:
+    default:
+        transport:
+            dsn: "rdkafka://"
+            global:
+                ### Make sure this is unique for each application / consumer group and does not change
+                ### Otherwise, Kafka won't be able to track your last offset and will always start according to
+                ### `auto.offset.reset` setting.
+                ### See Kafka documentation regarding `group.id` property if you want to know more
+                group.id: 'foo-app'
+                metadata.broker.list: 'example.com:1000'
+            topic:
+                auto.offset.reset: beginning
+            ### Commit async is true by default since version 0.9.9.
+            ### It is suggested to set it to true in earlier versions since otherwise consumers become extremely slow,
+            ### waiting for offset to be stored on Kafka before continuing.
+            commit_async: true
+        client: ~
+```
+
+[back to index](index.md)

pkg/rdkafka/RdKafkaConsumer.php

@@ -51,7 +51,7 @@ public function __construct(KafkaConsumer $consumer, RdKafkaContext $context, Rd
         $this->context = $context;
         $this->topic = $topic;
         $this->subscribed = false;
-        $this->commitAsync = false;
+        $this->commitAsync = true;
 
         $this->setSerializer($serializer);
     }