NAME

       CURLSHOPT_LOCKFUNC - mutex lock callback

SYNOPSIS

       #include <curl/curl.h>

       void lockcb(CURL *handle, curl_lock_data data, curl_lock_access access,
                   void *clientp);

       CURLSHcode curl_share_setopt(CURLSH *share, CURLSHOPT_LOCKFUNC, lockcb);

DESCRIPTION

       Set a mutex lock callback for the share object, to allow it to get used by multiple threads concurrently.
       There is a corresponding CURLSHOPT_UNLOCKFUNC(3) callback called when the mutex is again released.

       The lockcb argument must be a pointer to a function matching the prototype shown above. The arguments  to
       the callback are:

       handle is the currently active easy handle in use when the share object is intended to get used.

       The  data  argument  tells  what  kind  of data libcurl wants to lock. Make sure that the callback uses a
       different lock for each kind of data.

       access defines what access type libcurl wants, shared or single.

       clientp is the private pointer you set with CURLSHOPT_USERDATA(3).  This pointer is not used  by  libcurl
       itself.

PROTOCOLS

       This functionality affects all supported protocols

EXAMPLE

       extern void mutex_lock(CURL *handle, curl_lock_data data,
                              curl_lock_access access, void *clientp);

       int main(void)
       {
         CURLSHcode sh;
         CURLSH *share = curl_share_init();
         sh = curl_share_setopt(share, CURLSHOPT_LOCKFUNC, mutex_lock);
         if(sh)
           printf("Error: %s\n", curl_share_strerror(sh));
       }

AVAILABILITY

       Added in curl 7.10.3

RETURN VALUE

       CURLSHE_OK  (zero)  means  that  the  option  was  set  properly,  non-zero  means an error occurred. See
       libcurl-errors(3) for the full list with descriptions.

SEE ALSO

       CURLSHOPT_UNLOCKFUNC(3), curl_share_cleanup(3), curl_share_init(3), curl_share_setopt(3)