Remove special iterators from CleverDict

[joaquimg]

These were no help at all, on the contrary.

Before:

julia> main()
typeof(keys(d)) = Vector{MathOptInterface.VariableIndex}
  0.361756 seconds (2 allocations: 762.939 MiB, 19.29% gc time)
  0.064835 seconds

After:

julia> main()
typeof(keys(d)) = Base.KeySet{MathOptInterface.VariableIndex, MathOptInterface.Utilities.CleverDicts.CleverDict{MathOptInterface.VariableIndex, Int64, typeof(MathOptInterface.Utilities.CleverDicts.key_to_index), typeof(MathOptInterface.Utilities.CleverDicts.index_to_key)}}
  0.032200 seconds
  0.062263 seconds

Code:

using MathOptInterface

const CleverDicts = MathOptInterface.Utilities.CleverDicts

function build(N::Int)
    d = CleverDicts.CleverDict{MathOptInterface.VariableIndex, Int}()
    for i in 1:N
        CleverDicts.add_item(d, i)
    end
    return d
end

function test2_k(d, N)
    val = 0
    for k in keys(d)
        val += k.value
    end
    @assert val == N*(N+1)/ 2 #sum(1:N)
end

function test2_v(d, N)
    val = 0
    for v in values(d)
        val += v
    end
    @assert val == N*(N+1)/ 2 #sum(1:N)
end

function main()
    N = 100_000_000
    d = build(N)

    @show typeof(keys(d))

    @time test2_k(d, N)
    @time test2_v(d, N)

end

main()

[odow]

So I guess the issue was that we were returning the concrete list of keys, instead of a lazy evaluator?

[joaquimg]

exactly!

[odow]

I'm all for removing complexity.