curl_easy_upkeep.3 2.7 KB

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