Fix resetting of LivelinessLostStatus::total_changes (#2782)

* Refs #14982. Fix `DataWriter::get_liveliness_lost_status()`

* Apply suggestions from code review

Co-authored-by: Eduardo Ponz Segrelles <eduardoponz@eprosima.com>

Co-authored-by: Eduardo Ponz Segrelles <eduardoponz@eprosima.com>
(cherry picked from commit b5f87dd)

src/cpp/fastdds/publisher/DataWriterImpl.cpp

@@ -1107,12 +1107,16 @@ void DataWriterImpl::InnerDataWriterListener::on_liveliness_lost(
         fastrtps::rtps::RTPSWriter* /*writer*/,
         const fastrtps::LivelinessLostStatus& status)
 {
+    data_writer_->update_liveliness_lost_status(status);
     StatusMask notify_status = StatusMask::liveliness_lost();
     DataWriterListener* listener = data_writer_->get_listener_for(notify_status);
     if (listener != nullptr)
     {
-        listener->on_liveliness_lost(
-            data_writer_->user_datawriter_, status);
+        LivelinessLostStatus callback_status;
+        if (ReturnCode_t::RETCODE_OK == data_writer_->get_liveliness_lost_status(callback_status))
+        {
+            listener->on_liveliness_lost(data_writer_->user_datawriter_, callback_status);
+        }
     }
     data_writer_->user_datawriter_->get_statuscondition().get_impl()->set_status(notify_status, true);
 }
@@ -1406,10 +1410,8 @@ ReturnCode_t DataWriterImpl::get_liveliness_lost_status(
     {
         std::unique_lock<RecursiveTimedMutex> lock(writer_->getMutex());
 
-        status.total_count = writer_->liveliness_lost_status_.total_count;
-        status.total_count_change = writer_->liveliness_lost_status_.total_count_change;
-
-        writer_->liveliness_lost_status_.total_count_change = 0u;
+        status = liveliness_lost_status_;
+        liveliness_lost_status_.total_count_change = 0u;
     }
 
     user_datawriter_->get_statuscondition().get_impl()->set_status(StatusMask::liveliness_lost(), false);
@@ -1491,6 +1493,14 @@ OfferedIncompatibleQosStatus& DataWriterImpl::update_offered_incompatible_qos(
     return offered_incompatible_qos_status_;
 }
 
+LivelinessLostStatus& DataWriterImpl::update_liveliness_lost_status(
+        const fastrtps::LivelinessLostStatus& liveliness_lost_status)
+{
+    liveliness_lost_status_.total_count = liveliness_lost_status.total_count;
+    liveliness_lost_status_.total_count_change += liveliness_lost_status.total_count_change;
+    return liveliness_lost_status_;
+}
+
 void DataWriterImpl::set_qos(
         DataWriterQos& to,
         const DataWriterQos& from,

src/cpp/fastdds/publisher/DataWriterImpl.hpp

@@ -394,7 +394,10 @@ class DataWriterImpl : protected rtps::IReaderDataFilter
     PublicationMatchedStatus publication_matched_status_;
 
     //! The offered deadline missed status
-    fastrtps::OfferedDeadlineMissedStatus deadline_missed_status_;
+    OfferedDeadlineMissedStatus deadline_missed_status_;
+
+    //! The liveliness lost status
+    LivelinessLostStatus liveliness_lost_status_;
 
     //! The offered incompatible qos status
     OfferedIncompatibleQosStatus offered_incompatible_qos_status_;
@@ -511,6 +514,15 @@ class DataWriterImpl : protected rtps::IReaderDataFilter
     OfferedIncompatibleQosStatus& update_offered_incompatible_qos(
             PolicyMask incompatible_policies);
 
+    /*!
+     * @brief Updates liveliness lost status.
+     *
+     * @param[in] liveliness_lost_status Liveliness lost status coming from RTPS layer.
+     * @return Current liveliness lost status.
+     */
+    LivelinessLostStatus& update_liveliness_lost_status(
+            const fastrtps::LivelinessLostStatus& liveliness_lost_status);
+
     /**
      * Returns the most appropriate listener to handle the callback for the given status,
      * or nullptr if there is no appropriate listener.