Redis Cache By Xon 2.18.0

• Restore XF2.1 support

• Fix high availability support where css updates would be sent to a possible readonly replica instead of the writable instance

Disable behavior which caused css.php to return a 404 on an invalid template.
For the old behaviour of returning a HTTP 404 response, set this config.php option:

PHP:

$config['svForce404OnEmptyCss'] = true;

High avaliability config default change:
Change default value for retry_reads_on_primary config option to true as this guards against unexpected replication delays
Remove unexpected differences for XF2.2 and XF2.3 support (only tested on XF2.2)
When displaying redis version, include the redis varaint type.
Known variants are keydb & dragonflydb.
Dragonflydb does not appear to support IO stats at the moment

High avaliability config default change:
Change default value for retry_reads_on_primary config option to true as this guards against unexpected replication delays
Remove unexpected differences for XF2.2 and XF2.3 support (only tested on XF2.2)
When displaying redis version, include the redis varaint type.
Known variants are keydb & dragonflydb.
Dragonflydb does not appear to support IO stats at the moment

• Fix helper code to expire/purge redis keys did not support non-main cache backends.
• If using a separate caching backend for css, old styling was not actively expired as expected, resulting in higher memory usage
• If 3rd party code uses expireCacheByPattern/purgeCacheByPattern function, the new nullable 'cache' parameter should be used

Update credis library
Fix possible php 8.1 compatibility issue

Display maximum memory and maximum memory policy in admincp redis status information block for troubleshooting purposes

• Fix "call to a member function setRedisConnector() on null" when using a non-default advanced configuration option

• Remove displaying if Lua is configured or not, and remove the Lua enable/disable option.
  • Lua support was first added to redis v2.6.0, and this add-on required redis v3
• Rework caching provider code in preparation for XenForo 2.3
  • XF have documented they are switching from Doctrine/Cache to Symfony/Cache
  • I have not tested this on XF2.3, and have coded against the public interfaces of the Symfony/Cache package.
  • A future release may be required for full XF2.3 compatibility.