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- .\" generated by cd2nroff 0.1 from CURLOPT_UPKEEP_INTERVAL_MS.md
- .TH CURLOPT_UPKEEP_INTERVAL_MS 3 "2025-01-17" libcurl
- .SH NAME
- CURLOPT_UPKEEP_INTERVAL_MS \- connection upkeep interval
- .SH SYNOPSIS
- .nf
- #include <curl/curl.h>
- CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPKEEP_INTERVAL_MS,
- long upkeep_interval_ms);
- .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.
- The user needs to explicitly call \fIcurl_easy_upkeep(3)\fP 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 \fIcurl_easy_upkeep(3)\fP
- is called, an HTTP/2 PING frame is sent on the connection.
- .SH DEFAULT
- CURL_UPKEEP_INTERVAL_DEFAULT (currently defined as 60000L, which is 60 seconds)
- .SH PROTOCOLS
- This functionality affects all supported protocols
- .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 curl 7.62.0
- .SH RETURN VALUE
- Returns CURLE_OK
- .SH SEE ALSO
- .BR CURLOPT_TCP_KEEPALIVE (3)
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