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                     23: .TH curl_easy_upkeep 3 "31 Oct 2018" "libcurl 7.62.0" "libcurl Manual"
                     24: .SH NAME
                     25: curl_easy_upkeep - Perform any connection upkeep checks.
                     26: .SH SYNOPSIS
                     27: .B #include <curl/curl.h>
                     28: 
                     29: .BI "CURLcode curl_easy_upkeep(CURL *" handle ");"
                     30: .SH DESCRIPTION
                     31: 
                     32: Some protocols have "connection upkeep" mechanisms. These mechanisms usually
                     33: send some traffic on existing connections in order to keep them alive; this
                     34: can prevent connections from being closed due to overzealous firewalls, for
                     35: example.
                     36: 
                     37: Currently the only protocol with a connection upkeep mechanism is HTTP/2: when
                     38: the connection upkeep interval is exceeded and \fIcurl_easy_upkeep(3)\fP
                     39: is called, an HTTP/2 PING frame is sent on the connection.
                     40: 
                     41: This function must be explicitly called in order to perform the upkeep work.
                     42: The connection upkeep interval is set with
                     43: \fICURLOPT_UPKEEP_INTERVAL_MS(3)\fP.
                     44: 
                     45: .SH AVAILABILITY
                     46: Added in 7.62.0.
                     47: .SH RETURN VALUE
                     48: On success, returns \fBCURLE_OK\fP.
                     49: 
                     50: On failure, returns the appropriate error code.
                     51: 
                     52: .SH EXAMPLE
                     53: .nf
                     54: CURL *curl = curl_easy_init();
                     55: if(curl) {
                     56:   /* Make a connection to an HTTP/2 server. */
                     57:   curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
                     58: 
                     59:   /* Set the interval to 30000ms / 30s */
                     60:   curl_easy_setopt(curl, CURLOPT_UPKEEP_INTERVAL_MS, 30000L);
                     61: 
                     62:   curl_easy_perform(curl);
                     63: 
                     64:   /* Perform more work here. */
                     65: 
                     66:   /* While the connection is being held open, curl_easy_upkeep() can be
                     67:      called. If curl_easy_upkeep() is called and the time since the last
                     68:      upkeep exceeds the interval, then an HTTP/2 PING is sent. */
                     69:   curl_easy_upkeep(curl);
                     70: 
                     71:   /* Perform more work here. */
                     72: 
                     73:   /* always cleanup */
                     74:   curl_easy_cleanup(curl);
                     75: }
                     76: 
                     77: .fi