On Tue, May 09, 2023 at 10:53:18AM +0000, Alan Huang wrote:
> The code of resizable hash table has been updated so that it doesn't
> need to compute the hash twice since 2019. Here are some related
> commits:
> 2ea492bbab9d ("datatruct/hash: Don't recompute hashes in hashtab_add()")
> 2a7f20d234e7 ("datastruct/hash: Don't recompute hashes in hashtab_del()")
> ...
> So, the patch removes the outdated content.
>
> Signed-off-by: Alan Huang <mmpgouride@xxxxxxxxx>
> Reviewed-by: Akira Yokosawa <akiyks@xxxxxxxxx>
Good catch! Queued and pushed, thank you both!
Thanx, Paul
> ---
> datastruct/datastruct.tex | 29 +++--------------------------
> 1 file changed, 3 insertions(+), 26 deletions(-)
>
> diff --git a/datastruct/datastruct.tex b/datastruct/datastruct.tex
> index 8c2bfc16..0242ccc7 100644
> --- a/datastruct/datastruct.tex
> +++ b/datastruct/datastruct.tex
> @@ -2017,32 +2017,10 @@ which could allow the compiler to inline the resulting fixed functions,
> eliminating not only the overhead of the call instruction, but the
> argument marshalling as well.
>
> -In addition, the resizable hash table is designed to fit an API
> -that segregates bucket selection from concurrency control.
> -Although this allows a single torture test to exercise all the hash-table
> -implementations in this chapter, it also means that many operations
> -must compute the hash and interact with possible resize operations twice
> -rather than just once.
> -In a performance-conscious environment, the \co{hashtab_lock_mod()}
> -function would also return a reference to the bucket selected, eliminating
> -the subsequent call to \co{ht_get_bucket()}.
> -
> -\QuickQuizSeries{%
> -\QuickQuizB{
> - Couldn't the \path{hashtorture.h} code be modified to accommodate
> - a version of \co{hashtab_lock_mod()} that subsumes the
> - \co{ht_get_bucket()} functionality?
> -}\QuickQuizAnswerB{
> - It probably could, and doing so would benefit all of the
> - per-bucket-locked hash tables presented in this chapter.
> - Making this modification is left as an exercise for the
> - reader.
> -}\QuickQuizEndB
> -%
> -\QuickQuizE{
> +\QuickQuiz{
> How much do these specializations really save?
> Are they really worth it?
> -}\QuickQuizAnswerE{
> +}\QuickQuizAnswer{
> The answer to the first question is left as an exercise to
> the reader.
> Try specializing the resizable hash table and see how much
> @@ -2051,8 +2029,7 @@ the subsequent call to \co{ht_get_bucket()}.
> instead be answered with respect to a specific use case.
> Some use cases are extremely sensitive to performance and
> scalability, while others are less so.
> -}\QuickQuizEndE
> -}
> +}\QuickQuizEnd
>
> All that aside, one of the great benefits of modern hardware compared
> to that available when I first started learning to program back in
> --
> 2.34.1
>
