Using std.container with std.allocator

[Etienne]

I'm trying to implement a caching container that cleans up after its 
items based on expiration of nodes. I'd like to use the new 
std.allocator to make sure it's restricted to a region in memory.

The documentation of std.container states that Array uses malloc/free, 
but does it fallback on the (SharedFreelist) std.allocator if it's used 
like this:

struct Item {
        uint hashid;
        uint hashkey;
        U value;
        time_t added;
}
        
SharedFreelist!(BinaryHeap!(Array!(Item), "a.added < b.added")) m_store;

I need the ability sort by "Item.added" which is why I use BinaryHeap!Array.

How would one go about doing this if it's not possible through Array?