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

[Mike Gray <mike@xxxxxxxxxxxx>]

Anyone know if the git repository for the libevent book has changed or
gone away?  I tried updating using "git pull" as I already had a
previous copy that used to update fine the same way, but now I am
getting: "fatal: The remote end hung up unexpectedly".  origin in my
.git/config is "git://git.torproject.org/~nickm/git/lebook".


On Fri, Jan 29, 2010 at 7:00 AM, Jonas Romfelt <jonas@xxxxxxxxxx> wrote:
> 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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>>
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