gen_fsm:send_after | start_timer

Sean Hinde <>
Mon Jul 9 19:01:43 CEST 2001


> Hi,
> I do not have a decent work environment to do any tests 
> right, but I believe
> that an attempt at cleaning up the timer module has been 
> made. The design rule
> in the AXD is from 1996, and a lot has changed since then. I 
> do not think the
> ban is in the updated design rules.
> 
> I notice that the timers are still inserted in lists using 
> insertion sort, so if
> timing is still a problem (How many timers will you have 
> running at any one
> time?), I would personally rewrite the timer module instead 
> of complicating the
> FSMs.

Yes, I thought some more since your last post and also decided fixing timer
would be more in line with the general ethos.. Yet I just spent the last
couple of hours getting my head around a particularly complex gen_fsm and
have grown to really like my addition.. I had a big itch to scratch in doing
that change and it has helped enormously.

On a more definite note timer:apply_after/4 loses the nice property of
erlang:start_timer/3 that the timer ref is included in the sent message.
This is impossible using timer:apply_after because you don't know the ref
until after the message is sent(!)

Also my solution is much cleaner for users of gen_fsm because it does not
require a whole raft of exported functions just to wrap the timers.

And my solution is just about as efficient as timers get with only 1 message
sent - the actual timer.

So, I think that timer should be fixed,

And I will keep my change, rely on it making my head hurt less, enjoy the
fact that it makes my code more maintainable (IMHO), and hope others like it
:)

Cheers,

Sean



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