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.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2018, Daniel Stenberg, <[email protected]>, 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.haxx.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 "31 Oct 2018" "libcurl 7.62.0" "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