Hash-NoShareKeys

Hash-NoShareKeys.md

Hash::NoShareKeys

Provide a function Hash::NoShareKeys::apply to disable sharing of hash keys on the specified hash (reference).

See test.pl for a usage example.

Memory consumption on a single hash with one million keys (tested on a Linux Mint 18 system with self-compiled perl 5.28.0, unthreaded):

• with key sharing: size=80666224
• without key sharing: size=56666224

Performance:

• with key sharing: ~0.42s
• without key sharing: ~0.36s

.gitignore

/MYMETA.json
/MYMETA.yml
/Makefile
/NoShareKeys.bs
/NoShareKeys.c
/NoShareKeys.o
/blib
/pm_to_blib

Makefile.PL

use strict;
use ExtUtils::MakeMaker;

WriteMakefile
    (
	'NAME'	       => 'Hash::NoShareKeys',
	'VERSION_FROM' => 'NoShareKeys.pm',
    );

NoShareKeys.pm

package Hash::NoShareKeys;

our $VERSION = '0.01';

require XSLoader;
XSLoader::load();

1;

__END__

NoShareKeys.xs

/* -*- c-basic-offset:2 -*- */
#ifdef __cplusplus
extern "C" {
#endif
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#ifdef __cplusplus
}
#endif

MODULE = Hash::NoShareKeys	PACKAGE = Hash::NoShareKeys

PROTOTYPES: DISABLE

void
apply(HV* hv)
    CODE:
    HvSHAREKEYS_off(hv);

test.pl

#!/usr/bin/perl -w
# -*- cperl -*-

#
# Author: Slaven Rezic
#

use strict;
use Test::More 'no_plan';

use Hash::NoShareKeys;
use Devel::Peek;
use Devel::Size 'size';
use Time::HiRes 'time';

#use blib "../Devel-PLstrtab/";
#use Devel::PLstrtab;

for my $apply (0, 1) {
    my %h;
    Dump \%h;
    if ($apply) {
	Hash::NoShareKeys::apply(\%h);
    }
    my $t0 = time;
    for (1..1000000) { $h{$_} = undef }
    my $t1 = time;
    diag "duration=" . ($t1-$t0);
    Dump \%h;
    #diag scalar %h;
    diag "size=" . size \%h;

    #Devel::PLstrtab::dumpToStderr();
}

pass "yes";

__END__