Hi

Now we're down to details on the new functions for the multi interface that'll
allows apps to use other functions than select() and that should enable us to
build a more high-performance multi libcurl.

We're actually down to two only new functions. See the example app near the
end. As usual, comments are more than welcome!

/* our public socket type */
#ifdef WIN32
typedef SOCKET curl_socket_t;
#else
typedef int curl_socket_t;
#endif

/*
   curl_multi_update()

   Requests an update of the socket (file descriptor) status by getting none,
   one or multiple calls to the callback. It updates the status with changes
   since the previous time this function was used.

   The "what" argument has one of five values:

    0 CURL_POLL_NONE (0) - register, not interested in readiness
    1 CURL_POLL_IN - register, interested in read readiness
    2 CURL_POLL_OUT - register, interested in write readiness
    3 CURL_POLL_IN | CURL_POLL_OUT - register, interested in both
    4 CURL_POLL_REMOVE - deregister

*/
#define CURL_POLL_NONE 0
#define CURL_POLL_IN (1<<0)
#define CURL_POLL_OUT (1<<1)
#define CURL_POLL_REMOVE (1<<2)

typedef int (*curl_socket_callback)(CURL *easy, /* easy handle */
                                     curl_socket_t s, /* socket */
                                     int what, /* see above */
                                     void *userp); /* "private" pointer */

CURLMcode curl_multi_update(CURLM *multi_handle,
                             curl_socket_callback callback,
                             void *userp); /* anything you want to pass to the
                                              callback */

/*
   curl_multi_socket()

   An alternative version of curl_multi_perform() that allows the application
   to pass in one of the file descriptors that have been detected to have
   "action" on them and let libcurl perform. This allows libcurl to not have to
   scan through all possible file descriptors to check for this.

   NOTE: with this prototype, libcurl will need an internal hash table to map
   socket numbers to internal easy handles.

*/
CURLMcode curl_multi_socket(CURLM *multi_handle
                             curl_socket_t s,
                             int what);

/* Example (pseudo) code: */

  while ( still_running ) {

    curl_multi_update() /* get the callback called multiple times so that we
                           know what to wait for */

    /* Wait for action, on libcurl's sockets and on our own set of things.
       This can use select(), poll() or whatever high-performance polling
       function your particular OS provides */

    wait( ); /* with a timeout */

    /* When the wait is done, either by an action or by a timeout */

    while( list of action-sockets ) {

      curl_multi_socket(); /* pass on information to libcurl about what
                              action this file descriptors had */

    }

  }

-- 
      Daniel Stenberg -- http://curl.haxx.se -- http://daniel.haxx.se
       Dedicated custom curl help for hire: http://haxx.se/curl.html