Boost C++ Libraries: Ticket #9280: handling deferred events

attachment set

Mon, 21 Oct 2013 15:12:18 GMT

attachment → main.cc

Processing of deferred events for submachine

status changed

Christophe Henry — Mon, 18 Nov 2013 22:14:25 GMT

status new → assigned

Correct, this is a bug, precisely, entering the submachine does not check for waiting deferred events. This would be solved by adding inside do_entry inside state_machine.hpp:

handle_defer_helper<library_sm> defer_helper(m_deferred_events_queue); defer_helper.do_post_handle_deferred(HANDLED_TRUE);

before : process_message_queue(this);

This will have for effect that MSM will process ev_async_send_cmd_with_reply(1) when entering, and ev_async_send_cmd_with_reply(2) will be the last displayed text.

But frankly, after seeing this, I'm unsure whether it's a great idea to keep deferred events while leaving the submachine, I need to think about it.

To check if it solves your problem, I committed this fix in trunk rev. 86759.

Tue, 19 Nov 2013 07:51:45 GMT

Yes, with rev. 86759 output of test case is more expected. Actually, I need all deferred events be cleared on exit from state. For such behaviour I use this workaround:

        template <class Event, class Fsm>
        void on_exit(Event const&, Fsm& fsm)
        {
            std::cout << "On exit" << std::endl;
            op_.reset();
            fsm.template get_state<test_machine_front_t::st_connected&>().get_deferred_queue().clear();
        }

Christophe Henry — Sat, 23 Nov 2013 20:52:29 GMT

Ok, next possible solution, should make most happy: the decision of throwing away the deferred events upon exit is made by the history policy:

NoHistory: logically, we throw deferred events
AlwaysHistory: keep them all
ShallowHistory: like AlwayHistory, but depending on the event.

I committed to trunk, rev. 86799 (let's see if I get the last commit to svn ever ;-) ). Hope it solves your problem.

status changed; resolution set

Christophe Henry — Sat, 23 Nov 2013 20:52:47 GMT

status assigned → closed
resolution → fixed