Add different cache purging mechanism....

[erikdemarco]

Currently the way simple-cache handle expired cache is by bulk deleting all cache at the same time. Does it scaling well?

for example a site having hundred thousand of post cached. And the expiry_time set to 1 hour. and php time_limit is set to 30 seconds (php default settings). Will it finish delete all those in those timeframe?

Deleting all those pages at the same time doesn't feel like very friendly solution to server resources.

The standard way clearing cache (check and clear only when the url requested) is much more friendly to server resources and much more stable. This is also how nginx delete expired content. Nginx has been deployed many years by many giant sites. So this way of clearing the cache files dont need to be doubt anymore. It has been battle tested.