Sai/efficient union

[saiskee]

Description

This makes Union more efficient by checking if the input set is a sorted set, and taking advantage of merging two sorted lists (O(n+m))

[EItanya]

This feels very very specific and kind of strange to have on the interface to be honest

[saiskee]

We need a way to guarantee that the resource set in Union is sorted for more efficient merging. I'm open to other ideas on how we can do this.

[conradhanson]

I understand the need for knowing the set has been sorted by a specific type, but I don't like how this func is tied to implementation detail. I think making it generic with a name like SortedBy that uses/returns an enum value could make more sense. The enum would of course have to hold all known sorting types but this way it generalized, and the enum documents what all we sort by (yes that is implementation detail but abstracted).

[saiskee]

Impmlemented this change @conradhanson

[EItanya]

Don't these lists always have to be sorted? I actually think it's up to the caller to make sure they're sorted by the same thing. Union should just perform its operation.

[EItanya]

Then those are all sorted, also the other implementations could Union efficiently already.

[saiskee]

Unless two resource sets are sorted by different criteria, then we'd have to check the sorting criteria are the same. If not, fallback to the receiving set's sort method?

[saiskee]

@EItanya is there a change you want to see here? not sure if refactoring this and figuring out the perfect semantics is a blocker here.

[EItanya]

You're right the semantics don't have to be perfect, but I think worrying about the sorting is exposing too many details. I would recommend removing this entirely and leaving it up to the caller.

[saiskee]

Removed IsSortedBy and use sorted set merging by default.