[nanomsg] Re: Nanomsg state diagrams
- From: Paul Colomiets <paul@xxxxxxxxxxxxxx>
- To: Martin Sustrik <sustrik@xxxxxxxxxx>
- Date: Thu, 22 Aug 2013 20:16:34 +0300
Hi Martin,
On Thu, Aug 22, 2013 at 9:21 AM, Martin Sustrik <sustrik@xxxxxxxxxx> wrote:
> Super-cool!
>
> Where should we store such generated documentation? In the repo itself?
> Website? Elsewhere?
>
I don't think keeping generated pictures in git is nice (and dot files
are not useful either). But publishing them on the website would be
cool.
>
>> It seems that shutdown code is handled by a bunch of if statements at
>> the start of handlers, instead of switches. Why it's handled in a
>> special way?
>
>
> I wanted to blog about this but haven't have found time so far. Let me
> explain in short:
>
> State machine can have arbitrary number of states. In each state some
> sub-components are initialised some are not initialised.
>
> State machine shutdown (as if nn_close() is called) can occur in any state,
> thus, each "normal" state would have to have a chain of attached "shutdown"
> states to stop all the sub-components cleanly.
>
> That increases the number of states in thr state machine quadratically.
>
> To avoid proliferation of states, I've introduced special handling for
> shutdown, which simply stops anything that's still running, not depending on
> the initial state of the state machine (see attached picture).
>
Thanks. From the first sight it looked weird. But after looking at
several shutdown routines, it now looks super-clear.
It would be nice to separate this code into a block `if (self->state
== NN_FSM_STATE_STOPPING)` or a function or something, so that it's
clear that when you start shutting down, you never escape from this
series of shutdown states.
--
Paul
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