inconsistent cache key generation

[fritzmg]

There is an inconsistency with the cache key generation and usage. When a page is generated for the page cache, FrontendTemplate::addToCache always uses the current host for the cache key:
system/modules/core/classes/FrontendTemplate.php#L216-L220

$strCacheKey = \Environment::get('host') . '/empty.' . $objPage->language;
…
$strCacheKey = \Environment::get('host') . '/' . \Environment::get('request');

However, Automator::generateConfigCache always uses either the DNS setting from the page object or *:
system/modules/core/library/Contao/Automator.php#L539

$strBase = ($objPages->dns ?: '*');

So when the internal cache is active, the resulting system/cache/config/mapping.php will look like this for example:

<?php

return array (
  '*/empty.fallback' => '*/empty.de',
  '*/empty.de' => '*/empty.de',
);

But the cache file was generated with example.org/empty.de as its cache key.

This then leads to the start page never being served from the page cache, if the internal cache is built and no DNS setting was present in the website root.

[leofeyer]

So we need to adjust the FrontendTemplate class as follows, right?

// Server-side cache
if ($intCache > 0 && (\Config::get('cacheMode') == 'both' || \Config::get('cacheMode') == 'server'))
{
	$strBase = ($objPage->dns ?: '*');

	// If the request string is empty, use a special cache tag which considers the page language
	if (\Environment::get('request') == '' || \Environment::get('request') == 'index.php')
	{
		$strCacheKey = $strBase . '/empty.' . $objPage->language;
	}
	else
	{
		$strCacheKey = $strBase . '/' . \Environment::get('request');
	}

[fritzmg]

No, if you use $strBase = ($objPage->dns ?: '*'); for both it won't work. You must use it only for the empty request.

[leofeyer]

See #8695.