When does snitch_map get cleaned up?

[alexristich]

Looking through the code, it's not obvious when (if ever) snitch_map gets cleaned up after "promoting" a tracker to the block heuristic action in action_map. It must be getting cleaned up somehow, as snitch_map is significantly shorter than action_map, so it appears there is some culling taking place at some point.

[alexristich]

@cooperq As discussed, here is my understanding of snitch_map. If any of this is incorrect let me know!

The current behavior of snitch_map is to store all the domains where a third party tracker is detected. A heuristic action will only be generated for trackers that are detected on at least 3 separate TLDs, with 3 being the current threshold set in the code base.

Information is not cleared from snitch_map when a heuristic action is set for the corresponding entry in action_map, as the unique set of domains may be useful in the future for enhancements to the statistics and deep-dive analytics that might be provided to power users.

action_map is significantly larger than snitch_map because it includes everything from snitch_map, along with all domains in the cookieblock list, all DNT-compliant sites, etc.