Hi Jason

I'm doing HTTP transfers.

I was just reading the code, I didn't debug to check that multi calls
Curl_resolver_wait_resolv, but that's the impression I get by reading.
I'm using curl compiled with c-ares and observer blocking on a poll
call when resolving, which I suspect is the call to Curl_poll there,
since I just epoll in my application.

Regards.

On Sun, Dec 18, 2011 at 5:33 AM, Jason Glasgow <jglasgow_at_google.com> wrote:
> On Sat, Dec 17, 2011 at 9:33 PM, Pedro Larroy <pedro.larroy.lists_at_gmail.com>
> wrote:
>>
>> Hi
>>
>> After some flustration with blocking on dns requests while using the
>> multi interface with libevent (https://github.com/larroy/mycelium) I
>> investigated how curl uses ares and I came to the conclusion that the
>> design of asyn-ares.c is very limiting.
>
> I ran into a similar problem when I was trying to bind to an interface, and
> recently sent in some patches to address this problem.
> https://github.com/bagder/curl/commit/6e4835c795996ee92ac1aa78733f23a089f310a5
>
>> What's the point of having all the goodies of the multi interface to
>> use epoll etc, when waitperform function in asyn-ares.c just polls
>> waiting for DNS queries to finish?
>
>
> It only blocks when Curl_resolver_wait_resolv() is called and the code has a
> clear warning that this function should be avoided.  Are you doing http
> transfers? ftp transfers? socks?
>
> Curl_resolver_wait_resolv is still used in a few places:
>
> connect.c: when trying to bind to an interface and the user supplied a
> hostname.  You can avoid that by supplying an interface name with the if!xxx
> syntax.
> ftp.c - looks like it should be removed, but might be difficult.
> socks.c - ?
> transfer.c - ?
>
>  * Curl_resolver_wait_resolv()
>
>  *
>
>  * waits for a resolve to finish. This function should be avoided since
> using
>  * this risk getting the multi interface to "hang".
>
>
>>
>> I think the proper way would be to expose the resolving sockets up to
>> the multi interface so the whole system is really asynchronous. Is
>> there any reason why it wasn't done this way?
>>
>> Regards.
>>
>> Pedro.
>> -------------------------------------------------------------------
>> List admin: http://cool.haxx.se/list/listinfo/curl-library
>> Etiquette:  http://curl.haxx.se/mail/etiquette.html
>
>
>
> -------------------------------------------------------------------
> List admin: http://cool.haxx.se/list/listinfo/curl-library
> Etiquette:  http://curl.haxx.se/mail/etiquette.html

-------------------------------------------------------------------
List admin: http://cool.haxx.se/list/listinfo/curl-library
Etiquette: http://curl.haxx.se/mail/etiquette.html
Received on 2011-12-18