TYPO3 Core

Our Typo3 instance hosts thousands of websites, which is why we can not afford to clear the whole cache every time a website admin will change a value in the TS constants of its website, like the name of this website for example.

For this reason, we implemented a custom CacheManager that does more or less the same thing that the CacheService from extbase.

When asked to flush the cache of a website, our cache manager get the root uid of the website, then recursively list all of the website's pages, and build an array of the form:

['pageId_1', 'pageId_2', ...]

It finally call the TYPO3\CMS\Core\Cache\CacheManager like this:

$cacheManager->flushCachesByTags($tags);

But this command alone wasn't enough to force the page to rerender.

After hours of investigations, I found out adding these lines did the job, even if I'm unable to understand why:

        $connectionPool = GeneralUtility::makeInstance(ConnectionPool::class);
        $cnn = $connectionPool->getConnectionByName('Default');
        $cnn->beginTransaction();
        $sql = "update typo3.cache_hash h inner join typo3.cache_hash_tags t on h.id = t.id
                set h.expires = 0
                where t.tag = 'ident_TS_TEMPLATE';";
        $stmt = $cnn->prepare($sql);
        $stmt->executeQuery();
        $cnn->commit();

We are using Typo3 10.4.21 with php 7.2
The pages are designed with fluid
We're using custom viewhelpers and VHS (6.0.5) viewhelpers on these pages
We're using flux (9.5.0)