Added queue full notify callback

include/cppkafka/utils/buffered_producer.h

@@ -92,9 +92,9 @@ public:
         Async    ///< Empty the buffer and don't wait for acks.
     };
     enum class QueueFullNotification {
-        None,          ///< Don't notify
+        None,           ///< Don't notify (default).
-        EdgeTriggered, ///< Notify once. Application must call queue_full_trigger_reset() to enable again.
+        OncePerMessage, ///< Notify once per message.
-        EachOccurence  ///< Notify on each occurence.
+        EachOccurence   ///< Notify on each occurence.
     };
     /**
      * Concrete builder
@@ -144,6 +144,14 @@ public:
      * then FlushFailureCallback should not be set.
      */
     using FlushTerminationCallback = std::function<void(const MessageBuilder&, Error error)>;
+    
+    /**
+     * Callback to indicate a queue full error was received when producing.
+     *
+     * The MessageBuilder instance represents the message which triggered the error. This callback will be called
+     * according to the set_queue_full_notification() setting.
+     */
+    using QueueFullCallback = std::function<void(const MessageBuilder&)>;
 
     /**
      * \brief Constructs a buffered producer using the provided configuration
@@ -377,13 +385,6 @@ public:
      * Get the queue full notification type.
      */
     QueueFullNotification get_queue_full_notification() const;
-    
-    /**
-     * Reset the queue full notification trigger.
-     *
-     * This function has no effect unless QueueFullNotification == EdgeTriggered.
-     */
-    void queue_full_trigger_reset();
 
     /**
      * \brief Sets the message produce failure callback
@@ -449,6 +450,18 @@ public:
      */
     void set_flush_termination_callback(FlushTerminationCallback callback);
     
+    /**
+     * \brief Sets the local queue full error callback
+     *
+     * This callback will be called when local message production fails during a produce() operation according to the
+     * set_queue_full_notification() setting.
+     *
+     * \param callback
+     *
+     * \warning Do not call any method on the BufferedProducer while inside this callback
+     */
+    void set_queue_full_callback(QueueFullCallback callback);
+    
     struct TestParameters {
         bool force_delivery_error_;
         bool force_produce_error_;
@@ -523,6 +536,7 @@ private:
     ProduceTerminationCallback produce_termination_callback_;
     FlushFailureCallback flush_failure_callback_;
     FlushTerminationCallback flush_termination_callback_;
+    QueueFullCallback queue_full_callback_;
     ssize_t max_buffer_size_{-1};
     FlushMethod flush_method_{FlushMethod::Sync};
     std::atomic<size_t> pending_acks_{0};
@@ -532,7 +546,6 @@ private:
     int max_number_retries_{0};
     bool has_internal_data_{false};
     QueueFullNotification queue_full_notification_{QueueFullNotification::None};
-    bool queue_full_trigger_{true};
 #ifdef KAFKA_TEST_INSTANCE
     TestParameters* test_params_;
 #endif
@@ -837,11 +850,6 @@ BufferedProducer<BufferType, Allocator>::get_queue_full_notification() const {
     return queue_full_notification_;
 }
 
-template <typename BufferType, typename Allocator>
-void BufferedProducer<BufferType, Allocator>::queue_full_trigger_reset() {
-    queue_full_trigger_ = true;
-}
-
 template <typename BufferType, typename Allocator>
 void BufferedProducer<BufferType, Allocator>::set_produce_failure_callback(ProduceFailureCallback callback) {
     produce_failure_callback_ = std::move(callback);
@@ -867,13 +875,16 @@ void BufferedProducer<BufferType, Allocator>::set_flush_termination_callback(Flu
     flush_termination_callback_ = std::move(callback);
 }
 
+template <typename BufferType, typename Allocator>
+void BufferedProducer<BufferType, Allocator>::set_queue_full_callback(QueueFullCallback callback) {
+    queue_full_callback_ = std::move(callback);
+}
+
 template <typename BufferType, typename Allocator>
 template <typename BuilderType>
 void BufferedProducer<BufferType, Allocator>::produce_message(BuilderType&& builder) {
     using builder_type = typename std::decay<BuilderType>::type;
-    bool queue_full_notify = (queue_full_notification_ == QueueFullNotification::None) ? false :
+    bool queue_full_notify = queue_full_notification_ != QueueFullNotification::None;
-                             (queue_full_notification_ == QueueFullNotification::EdgeTriggered) ?
-                             queue_full_trigger_ : true;
     while (true) {
         try {
             MessageInternalGuard<builder_type> internal_guard(const_cast<builder_type&>(builder));
@@ -889,10 +900,8 @@ void BufferedProducer<BufferType, Allocator>::produce_message(BuilderType&& buil
                 producer_.poll();
                 // Notify application so it can slow-down production
                 if (queue_full_notify) {
-                    queue_full_notify = queue_full_trigger_ = false; //clear trigger and local state
+                    queue_full_notify = queue_full_notification_ == QueueFullNotification::EachOccurence;
-                    CallbackInvoker<Configuration::ErrorCallback>
+                    CallbackInvoker<QueueFullCallback>("queue full", queue_full_callback_, &producer_)(builder);
-                        ("error", get_producer().get_configuration().get_error_callback(), &get_producer())
-                        (get_producer(), static_cast<int>(ex.get_error().get_error()), ex.what());
                 }
             }
             else {