manpagez: man pages & more
man curl_easy_upkeep(3)
Home | html | info | man
curl_easy_upkeep(3)        Library Functions Manual        curl_easy_upkeep(3)


NAME

       curl_easy_upkeep - keep existing connections alive


SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_upkeep(CURL *handle);


DESCRIPTION

       Some protocols have "connection upkeep" mechanisms. These mechanisms
       usually send some traffic on existing connections in order to keep them
       alive; this can prevent connections from being closed due to
       overzealous firewalls, for example.

       Currently the only protocol with a connection upkeep mechanism is
       HTTP/2: when the connection upkeep interval is exceeded and
       curl_easy_upkeep(3) is called, an HTTP/2 PING frame is sent on the
       connection.

       This function must be explicitly called in order to perform the upkeep
       work.  The connection upkeep interval is set with
       CURLOPT_UPKEEP_INTERVAL_MS(3).

       If you call this function on an easy handle that uses a shared
       connection cache then upkeep is performed on the connections in that
       cache, even if those connections were never used by the easy handle.
       (Added in 8.10.0)


PROTOCOLS

       This functionality affects all supported protocols


EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           /* Make a connection to an HTTP/2 server. */
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           /* Set the interval to 30000ms / 30s */
           curl_easy_setopt(curl, CURLOPT_UPKEEP_INTERVAL_MS, 30000L);

           curl_easy_perform(curl);

           /* Perform more work here. */

           /* While the connection is being held open, curl_easy_upkeep() can be
              called. If curl_easy_upkeep() is called and the time since the last
              upkeep exceeds the interval, then an HTTP/2 PING is sent. */
           curl_easy_upkeep(curl);

           /* Perform more work here. */

           /* always cleanup */
           curl_easy_cleanup(curl);
         }
       }


AVAILABILITY

       Added in curl 7.62.0


RETURN VALUE

       This function returns a CURLcode indicating success or error.

       CURLE_OK (0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3). If CURLOPT_ERRORBUFFER(3) was set with
       curl_easy_setopt(3) there can be an error message stored in the error
       buffer when non-zero is returned.


SEE ALSO

       CURLOPT_TCP_KEEPALIVE(3), CURLOPT_TCP_KEEPIDLE(3)

libcurl                           2025-02-08               curl_easy_upkeep(3)

curl 8.12.0 - Generated Wed Feb 19 13:46:07 CST 2025
© manpagez.com 2000-2025
Individual documents may contain additional copyright information.