Re: [Libevent-users] Timeout Event Not Working?

[Jonas Romfelt <jonas@xxxxxxxxxx>]

Have a look at the libevent2 reference manual:
http://www.wangafu.net/~nickm/libevent-book/Ref3_eventloop.html, it'll
explain most stuff in detail and with really great examples.

cheers,
Jonas Romfelt


2010/1/29 Donghua Xu <donghua@xxxxxxxxx>:
> Thanks Jonas. I fixed the code like you suggested, using
> event_base_loop(global_event_base, 0) and evtimer_add(dummy_event,
> &five_seconds). Now the dummy_callback() is indeed called, but the
> event_base_loop() exited with a failed status, as show below:
>
> ***entering main()
> ***entering EventLoop()
> ***dummy_event=0x60e690
> ***in dummy_callback()
> event_base_loop() failed
> ***exiting EventLoop()
> ***exiting main()
>
> Any idea what might be wrong? Following is the current code:
>
> #include <stdlib.h>
> #include <stdio.h>
> #include "event2/event.h"
>
> struct event_base *global_event_base;
>
> static void dummy_callback(evutil_socket_t fd, short what, void *arg)
> {
>   printf("***in dummy_callback()\n");
> }
>
> static void* EventLoop(void *arg)
> {
>   printf("***entering EventLoop()\n");
>   global_event_base = event_base_new();
>   if (!global_event_base) {
>     printf("event_base_new() failed\n");
>     exit (-1);
>   }
>
>   struct timeval five_seconds = {5,0};
>   struct event *dummy_event =
>     evtimer_new(global_event_base, dummy_callback, arg);
>
>   printf("***dummy_event=%p\n", dummy_event);
>
>   evtimer_add(dummy_event, &five_seconds);
>
>   //  int ret = event_base_loop(global_event_base, EVLOOP_NONBLOCK);
>   int ret = event_base_loop(global_event_base, 0);
>   if (ret!=0)
>     printf("event_base_loop() failed\n");
>
>
>   printf("***exiting EventLoop()\n");
>   return NULL;
> }
>
> int main()
> {
>   printf("***entering main()\n");
>   EventLoop(NULL);
>   printf("***exiting main()\n");
>   fflush(stdout);
>   return 0;
> }
>
>
>
> On Fri, Jan 29, 2010 at 2:45 AM, Jonas Romfelt <jonas@xxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> if I'm not mistaken your call to event_base_loop() will not wait for
>> the timer event you added to expire beacuse the EVLOOP_NONBLOCK flag
>> is set. Simply because your 5 seconds timer has not yet expired when
>> the event_base_loop() is called.
>>
>> Try: event_base_loop(global_event_base, 0) or
>> event_base_loop(global_event_base, EVLOOP_ONCE) if you want to exit
>> the loop after the timer expired.
>>
>> Also, you could change event_add(dummy_event, &five_seconds) to
>> evtimer_add(dummy_event, &five_seconds). Event though it's just a
>> macro you never know when something under the API may change...
>>
>> cheers,
>> Jonas Romfelt
>>
>>
>>
>> 2010/1/29 Donghua Xu <donghua@xxxxxxxxx>
>> >
>> > Hi, I just wrote a simple program trying to use the timeout event in
>> > libevent 2.0.3-alpha. The source code is at the end of the email. I'm
>> > expecting to see a print out of "***in dummy_callback()", but this line does
>> > not show up at all. What I am seeing is only:
>> >
>> > ***entering main()
>> > ***entering EventLoop()
>> > ***dummy_event=0x60e690
>> > ***exiting EventLoop()
>> > ***exiting main()
>> >
>> > What am I doing wrong in the following source code? A lot of thanks in
>> > advance...
>> >
>> >
>> >
>> > #include <stdlib.h>
>> > #include <stdio.h>
>> > #include "event2/event.h"
>> >
>> > struct event_base *global_event_base;
>> >
>> > static void dummy_callback(evutil_socket_t fd, short what, void *arg)
>> > {
>> >   printf("***in dummy_callback()\n");
>> > }
>> >
>> > static void* EventLoop(void *arg)
>> > {
>> >   printf("***entering EventLoop()\n");
>> >   global_event_base = event_base_new();
>> >   if (!global_event_base) {
>> >     printf("event_base_new() failed\n");
>> >     exit (-1);
>> >   }
>> >
>> >   struct timeval five_seconds = {5,0};
>> >   struct event *dummy_event =
>> >     evtimer_new(global_event_base, dummy_callback, arg);
>> >
>> >   printf("***dummy_event=%p\n", dummy_event);
>> >
>> >   event_add(dummy_event, &five_seconds);
>> >
>> >   int ret = event_base_loop(global_event_base, EVLOOP_NONBLOCK);
>> >   if (ret!=0)
>> >     printf("event_base_loop() failed\n");
>> >
>> >
>> >   printf("***exiting EventLoop()\n");
>> >   return NULL;
>> > }
>> >
>> > int main()
>> > {
>> >   printf("***entering main()\n");
>> >   EventLoop(NULL);
>> >   printf("***exiting main()\n");
>> >   fflush(stdout);
>> >   return 0;
>> > }
>> >
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