Could apc.ttl be used rather than the hourly cleanup?

[nickchomey]

Inspecting the sqlite_delete_old function, i see that it simply clears the entire apcu cache each hour, which seems unnecessary. Perhaps rather than that, we could make use of the apcu.ttl config option?

Though I suppose this would require modifying the php.ini file, which is beyond most people's ability and even possibility on many hosts. Still, for those who DO set apcu.ttl, the plugin should probably respect that somehow - maybe check if it is set, and if so dont clear the cache?

ps there's also an outstanding PR to add a proper LRU eviction policy

[nickchomey]

This issue shows that ttl only clears when the entry is next read after ttl expires. So, if it isnt read, it doesnt get removed. This could lead to the cache filling up.

I'm probably just splitting hairs with this issue. Likely best to just stick with the current functionality - re-populating from SQLite will be rapid.

[OllieJones]

I beat the snot out of the software by setting the APCu cache size to 1MiB and hammering on the web site. Things functioned correctly. I confess I'm not completely clear on what happened to APCu during that test, just that it kept functioning.

https://www.php.net/manual/en/apcu.configuration.php

[OllieJones]

The way delete_old works, it bulk deletes least recently updated entries to bring the cached data size down to the target. Because it bulk-deletes rather than individually deleting it's necessary to clear APCu instead of sniping individual entries.