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CURLOPT_HAPPY_EYEBALLS_TIMEcurl_easy_setopCURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS(3)


NAME

       CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS  - head start for ipv6 for happy eye-
       balls


SYNOPSIS

       #include <curl/curl.h>

       CURLcode  curl_easy_setopt(CURL	*handle,  CURLOPT_HAPPY_EYEBALLS_TIME-
       OUT_MS, long timeout);


DESCRIPTION

       Happy  eyeballs	is  an algorithm that attempts to connect to both IPv4
       and IPv6 addresses for dual-stack  hosts,  preferring  IPv6  first  for
       timeout milliseconds. If the IPv6 address cannot be connected to within
       that time then a connection attempt is made to the IPv4 address in par-
       allel. The first connection to be established is the one that is used.

       The range of suggested useful values for timeout is limited. Happy Eye-
       balls RFC 6555 says "It is  RECOMMENDED	that  connection  attempts  be
       paced  150-250 ms apart to balance human factors against network load."
       libcurl currently defaults to 200  ms.  Firefox	and  Chrome  currently
       default to 300 ms.


DEFAULT

       CURL_HET_DEFAULT (currently defined as 200L)


EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
	 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
	 curl_easy_setopt(curl, CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS, 300L);

	 curl_easy_perform(curl);

	 /* always cleanup */
	 curl_easy_cleanup(curl);
       }


AVAILABILITY

       Added in 7.59.0


RETURN VALUE

       Returns CURLE_OK

libcurl 7.63.0		       February 21CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS(3)

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