Do you use D's GC?

[jfondren]

On Tuesday, 3 August 2021 at 19:04:06 UTC, jfondren wrote:
> ```d
> void ensureHasRoom(ref ubyte[] buffer, size_t length) {
>   buffer.length = length; // this is a serious bottleneck
> }
>
> void ensureHasRoom(ref ubyte[] buffer, size_t length) {
>   if (buffer.length < length) {
>     buffer.length = length; // this is fine actually
>   }
> }
> ```
>
> The story is that the situation was improved by excluding only 
> those cases that should not have incurred any reallocations. 
> Every single invocation of the bottlenecking `ensureHasRoom` 
> that should have reallocated would still do so with the fixed 
> `ensureHasRoom`. So something else was going on.

ah. No, I get it: this was probably shrinking and then regrowing 
buffer.length across separate calls, which would incur 
reallocations on the regrowth.