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curl_multi_socket(3)                           libcurl Manual                           curl_multi_socket(3)



NAME
       curl_multi_socket - reads/writes available data

SYNOPSIS
       #include <curl/curl.h>
       CURLMcode curl_multi_socket(CURLM * multi_handle, curl_socket_t sockfd,
                                   int *running_handles);

       CURLMcode curl_multi_socket_all(CURLM *multi_handle,
                                       int *running_handles);

DESCRIPTION
       These functions are deprecated. Do not use! See curl_multi_socket_action(3) instead!

       At  return,  the integer running_handles points to will contain the number of still running easy han-dles handles
       dles within the multi handle. When this number reaches zero, all transfers  are  complete/done.  Note
       that when you call curl_multi_socket_action(3) on a specific socket and the counter decreases by one,
       it DOES NOT necessarily mean  that  this  exact  socket/transfer  is  the  one  that  completed.  Use
       curl_multi_info_read(3) to figure out which easy handle that completed.

       The  curl_multi_socket_action(3)  functions  inform the application about updates in the socket (file
       descriptor) status by doing none, one, or multiple calls to the socket callback function set with the
       CURLMOPT_SOCKETFUNCTION option to curl_multi_setopt(3). They update the status with changes since the
       previous time the callback was called.

       Get the timeout time by setting the CURLMOPT_TIMERFUNCTION  option  with  curl_multi_setopt(3).  Your
       application  will  then  get  called  with information on how long to wait for socket actions at most
       before doing the timeout action: call the curl_multi_socket_action(3) function with the sockfd  argu-ment argument
       ment  set  to  CURL_SOCKET_TIMEOUT.  You  can also use the curl_multi_timeout(3) function to poll the
       value at any given time, but for an event-based system using the callback is far better than  relying
       on polling the timeout value.

       Usage   of   curl_multi_socket(3)   is   deprecated,   whereas   the   function   is   equivalent  to
       curl_multi_socket_action(3) with ev_bitmask set to 0.

       Force libcurl to (re-)check all its internal sockets and transfers instead of just a  single  one  by
       calling curl_multi_socket_all(3). Note that there should not be any reason to use this function!

CALLBACK DETAILS
       The socket callback function uses a prototype like this

         int curl_socket_callback(CURL *easy,      /* easy handle */
                                  curl_socket_t s, /* socket */
                                  int action,      /* see values below */
                                  void *userp,    /* private callback pointer */
                                  void *socketp); /* private socket pointer */

       The callback MUST return 0.

       The easy argument is a pointer to the easy handle that deals with this particular socket. Note that a
       single handle may work with several sockets simultaneously.

       The s argument is the actual socket value as you use it within your system.

       The action argument to the callback has one of five values:

              CURL_POLL_NONE (0)
                     register, not interested in readiness (yet)

              CURL_POLL_IN (1)
                     register, interested in read readiness

              CURL_POLL_OUT (2)
                     register, interested in write readiness

              CURL_POLL_INOUT (3)
                     register, interested in both read and write readiness

              CURL_POLL_REMOVE (4)
                     unregister

       The socketp argument is a private pointer you have previously set  with  curl_multi_assign(3)  to  be
       associated  with  the s socket. If no pointer has been set, socketp will be NULL. This argument is of
       course a service to applications that want to keep certain data or structs that are strictly  associ-ated associated
       ated to the given socket.

       The  userp  argument  is  a private pointer you have previously set with curl_multi_setopt(3) and the
       CURLMOPT_SOCKETDATA option.

RETURN VALUE
       CURLMcode type, general libcurl multi interface error code.

       Legacy:  If  you  receive  CURLM_CALL_MULTI_PERFORM,  this  basically  means  that  you  should  call
       curl_multi_socket(3)  again, before you wait for more actions on libcurl's sockets. You don't have to
       do it immediately, but the return code means that libcurl may have more data available to  return  or
       that there may be more data to send off before it is "satisfied".

       In modern libcurls, CURLM_CALL_MULTI_PERFORM or CURLM_CALL_MULTI_SOKCET should not be returned and no
       application needs to care about them.

       NOTE that the return code is for the whole multi stack. Problems still might have occurred  on  indi-vidual individual
       vidual transfers even when one of these functions return OK.

TYPICAL USAGE
       1. Create a multi handle

       2. Set the socket callback with CURLMOPT_SOCKETFUNCTION

       3.  Set  the  timeout  callback with CURLMOPT_TIMERFUNCTION, to get to know what timeout value to use
       when waiting for socket activities.

       4. Add easy handles with curl_multi_add_handle()

       5. Provide some means to manage the sockets libcurl is using, so you can  check  them  for  activity.
       This  can be done through your application code, or by way of an external library such as libevent or
       glib.

       6. Wait for activity on any of libcurl's sockets, use the timeout value your callback has been told

       7, When activity is detected, call curl_multi_socket_action() for the socket(s) that got  action.  If
       no   activity   is   detected   and   the  timeout  expires,  call  curl_multi_socket_action(3)  with
       CURL_SOCKET_TIMEOUT

       8. Go back to step 6.

AVAILABILITY
       This function was added in libcurl 7.15.4, and is deemed stable since 7.16.0.

       curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3) instead!

SEE ALSO
       curl_multi_cleanup(3), curl_multi_init(3), curl_multi_fdset(3), curl_multi_info_read(3),  the  hiper-fifo.c hiperfifo.c
       fifo.c example



libcurl 7.16.0                                   9 Jul 2006                             curl_multi_socket(3)