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curl_easy_upkeep(3)                 libcurl                curl_easy_upkeep(3)


curl_easy_upkeep - Perform any connection upkeep checks.


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


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 curl_easy_upkeep(3) 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 CURLOPT_UPKEEP_INTERVAL_MS(3).


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); }


Added in 7.62.0.


On success, returns CURLE_OK. On failure, returns the appropriate error code.


CURLOPT_TCP_KEEPALIVE(3), CURLOPT_TCP_KEEPIDLE(3), libcurl 8.1.2 April 26, 2023 curl_easy_upkeep(3)

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