CURLOPT_UPKEEP_INTERVAL_MS(3)

1CURLOPT_UPKEEP_INTERVAL_MS(3c)url_easy_setopt optionCsURLOPT_UPKEEP_INTERVAL_MS(3)
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NAME

6       CURLOPT_UPKEEP_INTERVAL_MS - connection upkeep interval
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode   curl_easy_setopt(CURL  *handle,  CURLOPT_UPKEEP_INTERVAL_MS,
12       long upkeep_interval_ms);
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DESCRIPTION

15       Some protocols have "connection upkeep"  mechanisms.  These  mechanisms
16       usually send some traffic on existing connections in order to keep them
17       alive; this can prevent connections from being closed due to  overzeal‐
18       ous firewalls, for example.
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20       The  user needs to explicitly call curl_easy_upkeep(3) in order to per‐
21       form the upkeep work.
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23       Currently the only protocol  with  a  connection  upkeep  mechanism  is
24       HTTP/2:   when   the   connection   upkeep  interval  is  exceeded  and
25       curl_easy_upkeep(3) is called, an HTTP/2 PING frame is sent on the con‐
26       nection.
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DEFAULT

30       CURL_UPKEEP_INTERVAL_DEFAULT  (currently defined as 60000L, which is 60
31       seconds)
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PROTOCOLS

34       All
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EXAMPLE

37       CURL *curl = curl_easy_init();
38       if(curl) {
39         /* Make a connection to an HTTP/2 server. */
40         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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42         /* Set the interval to 30000ms / 30s */
43         curl_easy_setopt(curl, CURLOPT_UPKEEP_INTERVAL_MS, 30000L);
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45         curl_easy_perform(curl);
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47         /* Perform more work here. */
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49         /* While the connection is being held open, curl_easy_upkeep() can be
50            called. If curl_easy_upkeep() is called and the time since the last
51            upkeep exceeds the interval, then an HTTP/2 PING is sent. */
52         curl_easy_upkeep(curl);
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54         /* Perform more work here. */
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56         /* always cleanup */
57         curl_easy_cleanup(curl);
58       }
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AVAILABILITY

61       Added in 7.62.0
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RETURN VALUE

64       Returns CURLE_OK
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