Caching at higher levels than specified by maxZoom

[ear7h]

From what I understand here higher zooms correspond with higher numbers. However the code in the filecache and s3cache packages assume the opposite, not caching when the zoom level is lower than MaxZoom.

// inside Set() method

//	check for maxzoom
if fc.MaxZoom != nil && key.Z <= int(*fc.MaxZoom) {
	return nil
}

// do cache

Also, I think mechanism is makes odd use of pointers and uint types. I'm willing to change this but wanted to submit an issue for clarification.

[ARolek]

@ear7h you're correct about "lower zooms" being closer to zero, and this looks like a bug. Thanks for reporting it. I will add a test case to both the filecache and s3cache and get this fixed.

Regarding the uint / pointer piece being odd, I agree. This is because some of the typing is going through a transition. Tile requests come to tegola in the format of /:map_name/:z/:x/:y. Currently we parse the z/x/y values into int values, but then we hit a bug with invalid requests of negative values. You can see the checking happening here. The plan is to convert everything to uint values and drop the less than zero checking. This will also require an update to the cache interface and then some code cleanup to the various cache implementations. I will open another issue to track it.

[ear7h]

Okay sounds good. I'll look for those tests when you submit them and make corresponding ones for the rediscache

[ARolek]

@ear7h my recent PR (#314) has the max_zoom fix and associated tests. Thanks again for the report. Teach me to not write test cases... ;-)