Manual:$wgHTCPMulticastAddress

HTCP multicast purging: $wgHTCPMulticastAddress
What address to send udp HTCP purge packets if being used
Introduced in version:1.4.1
Removed in version:1.24.0 (Gerrit change 150761; git #0eed71b7)
Allowed values:(IP address)
Default value:false (1.9-1.23)
"224.0.0.85" (1.4.1-1.8)

Details

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Deprecated. Setting first appeared in 1.4.1, but was commented out in DefaultSettings.php . Set to false from 1.9.0. Replaced by $wgHTCPMulticastRouting in MediaWiki 1.20 and $wgHTCPRouting in MediaWiki 1.22 and subsequent versions.

HTCP is a method of purging entries from the Squid cache that can use multicast and udp which is faster then opening an http connection to every squid server.

The $wgHTCPMulticastAddress variable is deprecated as of MediaWiki 1.20.0 but is still recognized by being copied to the new one in includes/Setup.php :

// $wgHTCPMulticastRouting got renamed to $wgHTCPRouting in MediaWiki 1.22
// ensure back compatibility.
if ( !$wgHTCPRouting && $wgHTCPMulticastRouting ) {
        $wgHTCPRouting = $wgHTCPMulticastRouting;
}

// Initialize $wgHTCPRouting from backwards-compatible settings that comes from pre 1.20 version.
if ( !$wgHTCPRouting && $wgHTCPMulticastAddress ) {
        $wgHTCPRouting = array(
                '' => array(
                        'host' => $wgHTCPMulticastAddress,
                        'port' => $wgHTCPPort,
                )
        );
}

See also

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