[phobos] newCapacity function in array appending

[Walter Bright]

Steve Schveighoffer wrote:
> There is a couple issues with the growth rate of arrays in the array append 
> function.
>
> First, the newCapacity function is only called when the array must be 
> reallocated.  I believe this to be an error, I think the newCapacity function 
> should always be used, even if pages can be added.  This would use less cycles 
> searching for pages to append.
>
> Second, the newCapacity function seems to use the size of the element to 
> determine a percentage growth.  I feel this is an error.  I think the growth 
> factor should strictly be related to the amount of memory being requested, which 
> already takes into account the size of the element.
>
> At present, this means that arrays of ints grow 4x as fast as arrays of bytes.  
> And that's 4x in percentage terms, not in 4x the memory used.  The memory used 
> actually grows 16x faster.
>
> Does everyone agree with this?
>
> The relevant bug for this is http://d.puremagic.com/issues/show_bug.cgi?id=4412
>
>   

Empirically, memory usage seems to be self-similar, which means a 
percentage increase in size is more likely to be correct than a fixed 
increment.