storage-plus: Implement u128 key

[orkunkl]

I needed to implement a (Uint128, &Addr) composite keymap, since u128 is not implemented for PrimaryKey I was not able to.
Not sure if u128 is intentionally not implemented here, just pushing it here in case it is left over

[ueco-jb]

since u128 is not implemented for PrimaryKey I was not able to.
Not sure if u128 is intentionally not implemented here

Yes it was. #547 (comment)
The real question is - do you really need 128 bit key?
@maurolacy ?

[orkunkl]

I building an optimized version of Claim and a sorted index that will save a sorted list of a defined number of claims.
I am using prefixed keys but saving the data to key as well.

pub total_claim_sort_index: Map<'a, (u128, &'a Addr), bool>

To achieve the sorted claim list, I am indexing the total claim amount with the address as appended key, bool is just a placeholder.

[orkunkl]

Looks like doubling the size of every key will be very costly for this feature...

[maurolacy]

Looks like doubling the size of every key will be very costly for this feature...

Yes. We can add this, but better to avoid it.

My question would be, why you can't use u64 for your key? (Ah, because claim amount is u128)

Converting the key to a string would work too. Or using a tuple of two u64 values. Which is somewhat clumsy, but effective.

[maurolacy]

On second thought, I think this wouldn't hurt, as those bytes are in memory / stack in the first place, and do not hit storage.

Approving. Will create a follow-up issue to benchmark Key performance with and without u128 support, so we confirm this.

Update: See #695.