Have you asked Christian about this? -sc

--  
Sean Chittenden


On Nov 21, 2009, at 5:24 AM, Pau Garcia i Quiles  
<[email protected]> wrote:

> Hello,
>
> Answering myself (in a different mailing list, no less!), I'd say
> deadline_timer is broken.
>
> I've tested with the time_t_timer.cpp example from Asio itself. The
> test is very easy:
>
> - Say now it's 14:19:10
> - Start time_t_timer
> - Set time one hour back (to 13:19:10)
> - Timers never expire (it doesn't matter if you do wait() or  
> async_wait() )
>
> Tested on Mac OS X 10.6.2. To make testing easier, I set the expiry
> time to 20 seconds and used only one timer at a time (i. e. I
> commented out the second half of the example the first time and had
> only the wait() first, then did the opposite).
>
> One intriguing issue is if instead of setting the time back one our,
> you set the time forward one hour (15:19:10), the timer works. I don't
> have time to research why this happens (I was expecting the test to
> fail, too, as the point in time the timer is set to expire is never
> reached exactly but just passed by).
>
>
> On Sat, Nov 21, 2009 at 3:12 AM, OvermindDL1 <[email protected]>  
> wrote:
>> Greetings.
>>
>> I programming library that I use (WT) had a bug in their asynchronous
>> timer handling, and although they fixed it, they are thinking of
>> moving over to Boost::ASIO timers since they already use Boost::ASIO
>> for the networking stack.  However, an interesting question was posed
>> about how Boost::ASIO timers handle the time changing on the host
>> computer (which is a possible scenario for this library due to its
>> up-time requirements).  Below is the basic part of the thread in
>> question.  Does anyone know the answer?  I attempted a quick look
>> through the timer source, however I cannot really seem to tell  
>> since I
>> know not the internals of ASIO nor the posix datetime library in
>> Boost...
>>
>> On Fri, Nov 20, 2009 at 12:55 AM, Pau Garcia i Quiles
>> <[email protected]> wrote:
>>> On Fri, Nov 20, 2009 at 8:05 AM, Koen Deforche <[email protected]>  
>>> wrote:
>>>> Hey all,
>>>>
>>>> 2009/11/19 OvermindDL1 <[email protected]>:
>>>>>>> Speaking about WTimer, I think its implementation is wrong on  
>>>>>>> Unix and
>>>>>>> could be more precise on Windows (although I'm not sure more  
>>>>>>> precision
>>>>>>> is required; I've not checked if Wt::Time is used server-side).
>>>>>>
>>>>>> I haven't looked, but is there any reason that  
>>>>>> boost::asio::deadline_timer isn't being used to back WTimer?   
>>>>>> I'm pretty sure this addresses all of the concerns listed  
>>>>>> below.  -sc
>>>>>>
>>>>>>
>>>>>> http://www.boost.org/doc/libs/1_41_0/doc/html/boost_asio/reference/deadline_timer.html
>>>>>
>>>>> Much of Boost already handles a lot of things better, since  
>>>>> boost is
>>>>> linked in anyway then we should use them, they have already been  
>>>>> well
>>>>> debugged and optimized.
>>>>
>>>> That is very true. I guess a motivation at the time was to avoid  
>>>> the
>>>> dependency on boost date_time for such a seemingly easy thing.  
>>>> But in
>>>> the meantime, we are relying on boost date_time anyway, and it is
>>>> clear that it is not that seemingly easy ?
>>>
>>> Actually, it is pretty easy. You've got 90% of the code there.  
>>> Take a
>>> look at the OSG file I said. Fixing this on Unix is straightforward,
>>> fixing on Windows is easy too.
>>>
>>> Further, I think using boost date_time is not the right solution, as
>>> it does not provide timers - i. e. you'll be basing the timer on the
>>> clock time (hh:mm:ss) instead of processor ticks or some other  
>>> entity
>>> independent of clock time. If timers are based on hh:mm:ss -
>>> hh':mm':ss' differences, they will fail when you change the computer
>>> clock time.
>>>
>>> I have only looked slightly into the implementation of Asio timers  
>>> and
>>> they do not use gettimeofday but they don't use clock_gettime  
>>> either,
>>> therefore I wouldn't use them without carefully looking into the
>>> implementation.
>> _______________________________________________
>> Boost-users mailing list
>> [email protected]
>> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>
>
>
> -- 
> Pau Garcia i Quiles
> http://www.elpauer.org
> (Due to my workload, I may need 10 days to answer)
>
> --- 
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