Re: [Libevent-users] the relation between event loop and struct event variable lifetime and scope

   void func(){
     struct event ev1;
     event_set(&ev1, ...);   
     event_base_set(base, &ev);

     event_add(&ev1, ...)
   }

   int main(){     
      struct event_base * mybase = event_init();

      func();
      event_base_dispatch(base);
   }

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the more complete version is as above. you mean the event_init() will create 2 event bases, the default base

and mybase? why will the memory used for the event be overwritten by random data if it is added to the
default base? if it is added to mybase, there is no problem?

Basically what you want to do is:

- Create new events when needed with event_new()

- Add the new events to base with event_add()

- Free your events when done with event_free()
--------------------------------------------------------------------------------------------------------------

event_new() is in libevent version 2.0.xxx, I'm using libevent version 1.4xxxx

I think the following 3 lines can replace event_new()

     struct event ev1;
     event_set(&ev1, ...);   
     event_base_set(base, &ev);

I'm just afraid, if the event is created in a non-main sub-routine, then it is 

a local variable. its lifetime is inside that sub-routine. When event_add() is
called in that sub-routine, the event is added to event loop, but after that 

subroutine is finished, the local variable is game over. If libevent doesn't make
a copy of the event inside the event loop, there is a crash.

2013/5/22 Nir Soffer <nirsof@xxxxxxxxx>

On Wed, May 22, 2013 at 4:41 AM, wen lui <esolvepolito@xxxxxxxxx> wrote:
From stackoverflow I get to know that if I define a struct event variable in a function which is different from where event_base_dispatch()
is defined, this event will not be added to the event loop, as below, ev1 will not be added to event loop.
   void func(){
     struct event ev1;
This event is on the stuck...
     event_set(&ev1, ...);
     event_add(&ev1, ...)
And you added it to the default event base.

If you dispatch the default base, you probably crash (soon if you are lucky). The memory used for the event will be overwritten by random data when another function is called.
   }

   int main(){
      func();
Here you dispatch on another base.
      event_base_dispatch(base);
   }

my problem is that I can't estimate the number of events in advance(think about discrete-event-driven simulation 



if you know it, but I'm not using libevent for this purpose). so I have to create one event each time a call 
back function or its sub-function wants to insert an event into the event_loop. That's being said I need to create 
many events that are local varibles which are not seen by event_base_dispatch(base);
are there any workaround for my problem?
No, but reading libevent book may help.
http://www.wangafu.net/~nickm/libevent-book/

Basically what you want to do is:

- Create new events when needed with event_new()
- Add the new events to base with event_add()
- Free your events when done with event_free()