focal (3) curl_multi_socket_all.3.gz

Provided by: libcurl4-doc_7.68.0-1ubuntu2.25_all bug

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 handles
       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(3)  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(3)  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 argument  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  associated
       to the given socket.

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

       3. Set the timeout callback with CURLMOPT_TIMERFUNCTION(3), 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  hiperfifo.c
       example