Re: Judy array types

[Doug B. <dou...@ya...>]

John:

I believe that it was designed to return the easiest thing to cast (in C) to 

what it really is.  I.E. it could be a pointer to an unsigned long -or- another Pointer, 

dependingwhat the user put in that memory location.  It turned out (later)

that in C++ this was "awkward" for the Macros JLG() and friends.

Oops, your are talking about the "Judy array pointer".   We debated that one
a lot too.  I vaguely remember there was a caveat that made it more awkward
(to a type other than a void **).   Perhaps C has changed since then.
I think it had to do with one of the tools that did "type" checking (in the 90's).


The Judy API has always been awkward.  I have never been happy with it.
I have received a lot of criticism about it over the years.  I challenge

anyone to come up with a better one, but so far there have been no takers
(that actually deliver a Judy.h file with the prototypes that can possibly work).

I spend most of my time with the internals of Judy.  The API is just something
that C and C++ make awkward (or I am just not smart enough to make it better).


doug

 
Doug Baskins <dou...@ya...>

PS.  Much of the design of Judy was to overcome the CPU design (flaws) of
the early 2000's.  The Macros were done to avoid an extra subroutine
call -- which were extremely costly before the 2006 CPU designs (core 2 duo).

I now struggle with CPU cache/TLB design flaws (I think) which are very 
difficult-to-impossible to predict and/or program around.  The symptom is
an apparent TLB miss in the Text cache -- even when the Text working set
is using just 2 pages.  So far this "flaw" has been present in all generations
of Intel CPU's since.  AMD CPU's have been so slow, it is hard to tell.




>________________________________
>From: john skaller <sk...@us...>
>To: judy <jud...@li...>
>Sent: Wednesday, November 2, 2011 3:39 AM
>Subject: Judy array types
>
>Instead of a void* why not
>
>struct Judy1Array { void *data};
>struct JudyLArray { void *data};
>
>This has the small advantage that one can't confuse Judy1Array and JudyLArray,
>since they now have distinct types.
>
>--
>john skaller
>sk...@us...
>
>
>
>
>
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