a86c63ca
 Hu Chunming
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.\" **************************************************************************
.\" * _ _ ____ _
.\" * Project ___| | | | _ \| |
.\" * / __| | | | |_) | |
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" **************************************************************************
.\"
.TH curl_easy_upkeep 3 "November 05, 2020" "libcurl 7.77.0" "libcurl Manual"
.SH NAME
curl_easy_upkeep - Perform any connection upkeep checks.
.SH SYNOPSIS
.B #include <curl/curl.h>
.BI "CURLcode curl_easy_upkeep(CURL *" handle ");"
.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 AVAILABILITY
Added in 7.62.0.
.SH RETURN VALUE
On success, returns \fBCURLE_OK\fP.
On failure, returns the appropriate error code.
.SH EXAMPLE
.nf
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
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