Re: Need cancel() on async_resolve() to callback the resolve handler immediately

From: Richard Hodges (hodges.r_at_[hidden])
Date: 2021-08-25 08:27:22

There are a couple of convoluted ways to build cancellation into the linux
resolve() activity.
The problem is that the sockets and timers used for this are entirely
embedded in the OS-shipped library layer and not accessible to user code.
It's a bit of a mess that has never been cleaned up. There isn't much that
Asio can do about it.

At present the "cleanest" way is to fork a child process to do the resolve
call for you and async_wait on a pipe from that child. If you want to
cancel it, send the child a SIGKILL which will result in the wait on the
pipe completing with an error.

Ghastly I know...

On Wed, 25 Aug 2021 at 08:30, sandeep m.v <venkata.sandeep.m_at_[hidden]>
wrote:

> Thank you for the response.
>
> We build our application for multiple platforms, Windows, Linux, Android
> and iOS.
> If it is not possible to cancel, is there a way to close internal socket,
> so that it wont callback resolve handler?
> By that way, we can at least go ahead with our processing after our
> internal timeout assuming callback never happen later.
> Is that something possible?
>
>
>
> On Wed, Aug 25, 2021 at 1:29 AM Richard Hodges via Boost <
> boost_at_[hidden]> wrote:
>
>> On Linux async_resolve is currently implemented in terms of a spawned
>> thread which calls a synchronous function. It has a 30s timeout and can’t
>> be cancelled.
>>
>> On Tue, 24 Aug 2021 at 21:56, Vinnie Falco via Boost <
>> boost_at_[hidden]>
>> wrote:
>>
>> > On Tue, Aug 24, 2021 at 12:09 PM sandeep m.v via Boost
>> > <boost_at_[hidden]> wrote:
>> > > Can someone please help me with this?
>> >
>> > Are you by chance using Windows? What version?
>> >
>> > Thanks
>> >
>> > _______________________________________________
>> > Unsubscribe & other changes:
>> > http://lists.boost.org/mailman/listinfo.cgi/boost
>> >
>> --
>> Richard Hodges
>> hodges.r_at_[hidden]
>> office: [phone]
>> home: [phone]
>> mobile: [phone]
>>
>> _______________________________________________
>> Unsubscribe & other changes:
>> http://lists.boost.org/mailman/listinfo.cgi/boost
>>
>
>
> --
> Regards,
> Sandeep
> Mob# 9000707098
>