master-server/deps/curl/docs/libcurl/curl_easy_upkeep.3
2023-12-11 20:30:44 -05:00

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.TH curl_easy_upkeep 3 "31 Oct 2018" "libcurl" "libcurl"
.SH NAME
curl_easy_upkeep - Perform any connection upkeep checks.
.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.
.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 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), "