On Wed, 10 Dec 2014, Lindley French wrote:

This is pure libcurl talk so I took it off the curl-users list. However your
original mails have only showed up in the curl-users archive
(http://curl.haxx.se/mail/archive-2014-12/0009.html) and not in the
curl-library archive which makes me suspect you're not subscribed to
curl-library (yet). Please do before you respond to this so that your mail
reaches everyone!

> One thing isn't clear to me, though. If I have a thread dedicated to
> blocking on select() and then calling curl_multi_perform(), then it seems
> like I need to get my outgoing requests onto that thread somehow.

A single multi handle can handle any amount of incoming and outgoing requests.

> (In an async world, it seems like it shouldn't be necessary to do writing
> and reading on the same thread, but the prohibition against sharing curl
> handles between threads requires it.)

No it doesn't require it. You can have two threads, each with its own multi
handle and you can have one do downloads and one do uploads... But yeah, there
may be reasons why that isn't right for you.

> Question: is there a best practice for doing this in curl, or do I just have
> to hack something up with a deque and a mutex?

Why not simply add your outgoing work in a queue that you can read from as
often as possible in the select()-using thread? You can even trigger the
select() to return with a pipe or similar.

[from your follow-up mail]

> Question: is there a way to connect two curl handles to each other, so that
> writing to one causes the other to become readable? This would let me wake
> up a select() call at an arbitrary time.

Use a pipe.

> I could do this other ways, but I'm looking for a solution that will work on
> both Linux and Windows.

On Windows, select() can only wait on sockets so you'd have to create a socket
instead of a pipe. Less performant and more work, but should still be doable.

-- 
  / daniel.haxx.se
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