Tribblix: manual page: CURLOPT_UPKEEP_INTERVAL

CURLOPT_UPKEEP_INTERVAL_MS(3) Introduction to Library Functions

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

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

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).