1curl_easy_upkeep(3)             libcurl Manual             curl_easy_upkeep(3)
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NAME

6       curl_easy_upkeep - Perform any connection upkeep checks.
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode curl_easy_upkeep(CURL *handle);
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DESCRIPTION

14       Some  protocols  have  "connection upkeep" mechanisms. These mechanisms
15       usually send some traffic on existing connections in order to keep them
16       alive;  this can prevent connections from being closed due to overzeal‐
17       ous firewalls, for example.
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19       Currently the only protocol  with  a  connection  upkeep  mechanism  is
20       HTTP/2:   when   the   connection   upkeep  interval  is  exceeded  and
21       curl_easy_upkeep(3) is called, an HTTP/2 PING frame is sent on the con‐
22       nection.
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24       This  function must be explicitly called in order to perform the upkeep
25       work.  The connection upkeep interval is set with CURLOPT_UPKEEP_INTER‐
26       VAL_MS(3).
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AVAILABILITY

30       Added in 7.62.0.
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RETURN VALUE

33       On success, returns CURLE_OK.
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35       On failure, returns the appropriate error code.
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EXAMPLE

39       CURL *curl = curl_easy_init();
40       if(curl) {
41         /* Make a connection to an HTTP/2 server. */
42         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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44         /* Set the interval to 30000ms / 30s */
45         curl_easy_setopt(curl, CURLOPT_UPKEEP_INTERVAL_MS, 30000L);
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47         curl_easy_perform(curl);
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49         /* Perform more work here. */
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51         /* While the connection is being held open, curl_easy_upkeep() can be
52            called. If curl_easy_upkeep() is called and the time since the last
53            upkeep exceeds the interval, then an HTTP/2 PING is sent. */
54         curl_easy_upkeep(curl);
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56         /* Perform more work here. */
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58         /* always cleanup */
59         curl_easy_cleanup(curl);
60       }
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65libcurl 7.79.1                 November 05, 2020           curl_easy_upkeep(3)