.\" generated by cd2nroff 0.1 from curl_easy_upkeep.md
.TH curl_easy_upkeep 3 "2024-09-25" libcurl
.SH NAME
curl_easy_upkeep \- keep existing connections alive
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_upkeep(CURL *handle);
.fi
.SH 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 \fIcurl_easy_upkeep(3)\fP
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
\fICURLOPT_UPKEEP_INTERVAL_MS(3)\fP.

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)
.SH PROTOCOLS
This functionality affects all supported protocols
.SH EXAMPLE
.nf
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);
  }
}
.fi
.SH AVAILABILITY
Added in curl 7.62.0
.SH RETURN VALUE
On success, returns \fBCURLE_OK\fP.

On failure, returns the appropriate error code.
.SH SEE ALSO
.BR CURLOPT_TCP_KEEPALIVE (3),
.BR CURLOPT_TCP_KEEPIDLE (3)