[Ace-users] [ace-users] When an Ace_Reactor calls handle_timeout() on an Ace_Event_Handler, is it possible to, within the handle_timeout() call, get at the timer_id that is associated with that particular invocation?
Douglas C. Schmidt
schmidt at dre.vanderbilt.edu
Fri Feb 8 07:19:19 CST 2008
Thanks for using the PRF.
> ACE VERSION: 5.6.2
> HOST MACHINE and OPERATING SYSTEM:
> Not Available at the moment (sorry)/Red Hat 4
> TARGET MACHINE and OPERATING SYSTEM, if different from HOST:
> COMPILER NAME AND VERSION (AND PATCHLEVEL): Not Available at the moment
> THE $ACE_ROOT/ace/config.h FILE: Not Available at the moment (sorry)
> THE $ACE_ROOT/include/makeinclude/platform_macros.GNU FILE: Not
>Available at the moment (sorry)
> CONTENTS OF $ACE_ROOT/bin/MakeProjectCreator/config/default.features
> (used by MPC when you generate your own makefiles): Not Available at the
> AREA/CLASS/EXAMPLE AFFECTED:
> Ace_Reactor/Ace_Event_Handler. Nothing failed to compile, just
>trying to figure out how to do something.
> DOES THE PROBLEM AFFECT:
> COMPILATION? No.
> EXECUTION? Yes.
> OTHER (please specify)?
> I'm trying to get access to the timer_id value created when a
>schedule_timer() method is called
>from within the handle_timeout() call that results, but can't figure out
The best way to do this is to use the Asynchronous Completion Token
pattern (see POSA2 www.cs.wustl.edu/~schmidt/POSA/POSA2) that's
implemented with the ACE timer queues and the handle_timeout()
method. Here's some pseudo-code:
class My_Event_Handler : public ACE_Event_Handler
virtual int handle_timeout (const ACE_Time_Value &,
const void *act);
My_Event_Handler eh = new My_Event_Handler;
const void *timer_act = new long;
long timer_id = timer_queue->schedule (eh, timer_act, ....);
*timer_act = timer_id;
Now, when My_Event_Handler::handle_timeout() is called back you can
get the timer_id as follows:
int My_Event_Handler::handle_timeout (const ACE_Time_Value &,
const void *act)
long timer_id = *static_cast <long *> (act);
// .. Do something with timer_id
Naturally, you'll need to fix any typos in my pseudo-code ;-)
> Hi all, ACE newbie here. Sorry if this has been discussed, I
>searched and couldn't find anything. Basically,
>what I have is a message passing program that wants to read messages from an
>input socket and send them out an output socket.
>The only tricky part is that I want to either delay (for a set amount of
>time), or pause entirely, the sending of certain types of messages.
>My design was to have a first reactor that reads the input socket, checks
>the incoming messages, and passes them on to a second
>reactor via the schedule_timer() method. If the messages are to be sent
>immediately, I send it with a zero timeout value. If they are to
>be delayed, I send them with the appropriate delay value. The message
>content is passed within the act argument of the call, ensuring
>the appropriate message is associated with the appropriate event.
>The problem I have is that I also want to be able to change the delays of
>certain messages on the fly. That means if messages of type 1
>are to be delayed for 1 minute, but during that second the user decides to
>change the delay to 5 seconds, I need to update the delay on
>the existing timer events that have already been sent for that message type.
>My solution was this was to manually maintain the set of timer_id
>values that result from the schedule_timer() call, and upon a request for a
>change just call the reschedule method for active timer_id values
>associated with that message type. However, I need a way to then remove
>timer_id values from this manually maintained set, and that's
>where my question comes in. Is there a way to get at the timer_id
>associated with a particular handle_timeout() call, from within the
>handle_timeout() call itself (or even the add_/remove_reference() calls)?
>I'm a little surprised that I haven't yet found an easy way to do this
>because intuitively, if we are given access to the timer_id values and
>methods to manipulate their events, a relatively common approach would be to
>save them into some sort of pool, process them when needed,
>and then remove them from the pool when handle_timeout() is called and they
>are no longer needed. I'm guessing that I'm just not seeing
>the set of calls I would need to do to do this.
>Any help anyone could offer would be much appreciated, including alternative
>designs (which I already have, I just like mine better, so
>I'm trying to find a way to make it work).
Dr. Douglas C. Schmidt Professor and Associate Chair
Electrical Engineering and Computer Science TEL: (615) 343-8197
Vanderbilt University WEB: www.dre.vanderbilt.edu/~schmidt
Nashville, TN 37203 NET: d.schmidt at vanderbilt.edu
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