On Sat, 4 May 2013, Marc Hoersken wrote:

> I have no clue why there is a need for something like a closure_handle. Why
> can't the connection be freed with it's original handle? Daniel, can you
> elaborate on this one?

Sure. This is necessary because we do have connections that are independent of
easy handles. If we perform a number of requests using a multi handle with one
or more easy handles, and then remove all the easy handles from it again, the
connections are left in the connection cache within the multi handle but with
no easy handles present.

If you then for example close the multi handle, each of those connections need
to be shut down properly. Proper shutting down some protocols involves some
further communication, like a QUIT or a BYE command etc (such protocols are
FTP, SMTP etc that have the PROTOPT_CLOSEACTION bit set in the flags field).

The libcurl internals are designed to always work with an easy handle together
with a connection so we have an extra "closure_handle" around for when we need
to shut down this kind of connection that no longer is associated with a
"real" easy handle. An spare internal easy handle to do "closures" with!

-- 
  / daniel.haxx.se
-------------------------------------------------------------------
List admin: http://cool.haxx.se/list/listinfo/curl-library
Etiquette:  http://curl.haxx.se/mail/etiquette.html