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curl_easy_upkeep(3)                 libcurl                curl_easy_upkeep(3)

NAME
       curl_easy_upkeep - Perform any connection upkeep checks.

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).

EXAMPLE
       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
       On success, returns CURLE_OK.

       On failure, returns the appropriate error code.

SEE ALSO
       CURLOPT_TCP_KEEPALIVE(3),  CURLOPT_TCP_KEEPIDLE(3),

libcurl 8.1.2                   April 26, 2023             curl_easy_upkeep(3)