fixes for rmw callbacks in qos_event class (#2102)

Signed-off-by: Alberto Soragna <[email protected]>

Author: alsora

rclcpp/include/rclcpp/qos_event.hpp

@@ -214,10 +214,11 @@ class QOSEventHandlerBase : public Waitable
   void
   set_on_new_event_callback(rcl_event_callback_t callback, const void * user_data);
 
-  rcl_event_t event_handle_;
-  size_t wait_set_event_index_;
   std::recursive_mutex callback_mutex_;
   std::function<void(size_t)> on_new_event_callback_{nullptr};
+
+  rcl_event_t event_handle_;
+  size_t wait_set_event_index_;
 };
 
 template<typename EventCallbackT, typename ParentHandleT>

rclcpp/src/rclcpp/qos_event.cpp

@@ -40,9 +40,7 @@ QOSEventHandlerBase::~QOSEventHandlerBase()
   // This clearing is not needed for other rclcpp entities like pub/subs, since
   // they do own the underlying rmw entities, which are destroyed
   // on their rclcpp destructors, thus no risk of dangling pointers.
-  if (on_new_event_callback_) {
-    clear_on_ready_callback();
-  }
+  clear_on_ready_callback();
 
   if (rcl_event_fini(&event_handle_) != RCL_RET_OK) {
     RCUTILS_LOG_ERROR_NAMED(