https://issues.dlang.org/show_bug.cgi?id=2504: reserve for associative arrays

[Jon Degenhardt via Digitalmars-d]

On Wednesday, 2 November 2016 at 03:36:42 UTC, Andrei 
Alexandrescu wrote:
>
> Last time I looked our associative arrays were arrays of 
> singly-linked lists. It follows that in order to implement 
> reserve() we'd need a freelist allocator approach, which 
> preallocates a bunch of nodes in a single contiguous block of 
> memory.
>
Aren't associative arrays using open addressing for collision 
resolution? I'm looking at routines findSlotInsert() and 
findSlotLookup() here: 
https://github.com/dlang/druntime/blob/master/src/rt/aaA.d#L102

There is already a resize() routine: 
https://github.com/dlang/druntime/blob/master/src/rt/aaA.d#L141

The resize() routine takes the new size of the bucket array as an 
argument. Could a 'reserve' routine call this? Scanning through 
the code, it appears policy on size of the bucket array is 
established by callers to resize(), e.g. see the _aaRehash() 
function, which calls resize().