Added running_in_this_thread() wrapper.

include/mqtt/null_strand.hpp

@@ -56,6 +56,7 @@ struct null_strand {
             }
         );
     }
+    bool running_in_this_thread() const noexcept { return false; }
     void on_work_started() const noexcept {}
     void on_work_finished() const noexcept {}
     as::io_context& context() noexcept{ return ioc_; }

include/mqtt/tcp_endpoint.hpp

@@ -90,6 +90,10 @@ class tcp_endpoint : public socket {
         );
     }
 
+    MQTT_ALWAYS_INLINE bool running_in_this_thread() const override final {
+        return strand_.running_in_this_thread();
+    }
+
     MQTT_ALWAYS_INLINE as::ip::tcp::socket::lowest_layer_type& lowest_layer() override final {
         return tcp_.lowest_layer();
     }

include/mqtt/type_erased_socket.hpp

@@ -28,6 +28,7 @@ class socket {
     virtual void post(std::function<void()>) = 0;
     virtual void dispatch(std::function<void()>) = 0;
     virtual void defer(std::function<void()>) = 0;
+    virtual bool running_in_this_thread() const = 0;
     virtual as::ip::tcp::socket::lowest_layer_type& lowest_layer() = 0;
     virtual any native_handle() = 0;
     virtual void clean_shutdown_and_close(boost::system::error_code&) = 0;

include/mqtt/ws_endpoint.hpp

@@ -151,6 +151,10 @@ class ws_endpoint : public socket {
         );
     }
 
+    MQTT_ALWAYS_INLINE bool running_in_this_thread() const override final {
+        return strand_.running_in_this_thread();
+    }
+
 #if BOOST_VERSION >= 107000
 
     MQTT_ALWAYS_INLINE as::ip::tcp::socket::lowest_layer_type& lowest_layer() override final {