CURLOPT_UPKEEP_INTERVAL_MS(3)                         Library Functions Manual

NAME
       CURLOPT_UPKEEP_INTERVAL_MS - connection upkeep interval

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPKEEP_INTERVAL_MS,
                                 long upkeep_interval_ms);

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.

       The user needs to explicitly call curl_easy_upkeep(3) in order to
       perform the upkeep work.

       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.

DEFAULT
       CURL_UPKEEP_INTERVAL_DEFAULT (currently defined as 60000L, which is 60
       seconds)

PROTOCOLS
       All

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 7.62.0

RETURN VALUE
       Returns CURLE_OK

SEE ALSO
       CURLOPT_TCP_KEEPALIVE(3)

libcurl                          April 26 2024   CURLOPT_UPKEEP_INTERVAL_MS(3)