Bug fix for metadata caching

[jrfnl]

Sending this in as a separate PR as I want to keep it out of the discussion on PR #21.

I was wondering why the metadata cache files kept being updated (new save date/time) even when the cache shouldn't have expired yet.

That's when I found this. Basically any non-expired cache was being retrieved and then resaved with a new expiration timestamp, which - depending on the cache time chosen and how often the metadata gets retrieved - would mean that the cache effectively would never get refreshed.

[YahnisElsts]

Good catch. I can't believe I missed something like this.

Basically any non-expired cache was being retrieved and then resaved with a new expiration timestamp, which - depending on the cache time chosen and how often the metadata gets retrieved - would mean that the cache effectively would never get refreshed.

You mean it will be refreshed on every request, right?

[jrfnl]

I can't believe I missed something like this.

I missed it too until now....

You mean it will be refreshed on every request, right?

Actually, the way it was, the cache file would be resaved with a new expiration time, but with the old data. So except for the first time when the cache was created or in the unlikely case that no requests at all were made between the last save and the expiration time (1 week), the zip file would never be read out again for the metadata.

Now in a lot of ways this might not be a problem as when a new version of the file gets uploaded, it would have a new timestamp/filesize and therefore the cache would be invalid and a new one created, so data-wise there wasn't much of a problem.

However, what's the point of setting a cache with an expiration date if that expiration date is then effectively being overruled on every request/set to unlimited ?
Also: it meant effectively that no matter whether a cache was found or not we're writing/updating the cache file (not the data, just the file). Writing to disk on every request kind of defies the point of having a cache.

[YahnisElsts]

Actually, the way it was, the cache file would be resaved with a new expiration time, but with the old data.

In this case, the "old data" would be completely identical to the "new data" since the file hasn't changed. But yes, it's still a bug, and it leads to lots of superfluous disk writes. I'll merge your fix momentarily.