Re: hash of objects inside an instance

[Erik Colson]

On 29 Nov 2011, at 09:40, Tomas Doran wrote:

> 
> On 29 Nov 2011, at 00:29, Erik Colson wrote:
> 
>> This creates a lot of overhead by creating all the necessary objects.
>> I implemented it using a EmployeeDepartment class as would be the case when 
>> using RDBS. It works well, but I hope the app won't get too slow because of 
>> this...
> 
> Do you actually _know_ that this is a lot of overhead in real terms?
> 
> I.e. do you have profile results to show that this is the slowest part?
> 
> Otherwise I call premature optimisation.
> 
> Cheers
> t0m
> 


Here's some data. The testscript is added below. Results are as expected...

Employee1 is with using a supplementary class.
Employee2 is with using a hash where the keys are the strignification of the 
department objects.

Employee1 creation elapsed time: 4.398077 seconds!
Employee2 creation elapsed time: 2.870149 seconds!
Employee1 retrieve elapsed time: 0.297852 seconds!
Employee2 retrieve elapsed time: 0.25303 seconds!


######################################################################################
package Employee1;

use Moose;

has 'ID' => ( is => 'ro', isa => 'Num' );
has 'a' => ( is      => 'ro',
             isa     => 'ArrayRef[EmployeeDepartment]',
             traits  => ['Array'],
             default => sub { [] },
             handles => { add_employeedepartment  => 'push',
                          find_employeedepartment => 'first',
                          all_employeedepartments => 'elements'
             }
);

no Moose;

__PACKAGE__->meta->make_immutable;

1;

##################################################################################

package EmployeeDepartment;
use Moose;
has 'department' => ( is => 'ro', isa => 'Department' );
has 'percentage' => ( is => 'rw', isa => 'Num' );

no Moose;
__PACKAGE__->meta->make_immutable;
1;

##################################################################################
package Department;
use Moose;
has 'ID' => ( is => 'ro', isa => 'Num' );
no Moose;
__PACKAGE__->meta->make_immutable;
1;
##################################################################################

package Employee2;
use Moose;

has 'ID' => ( is => 'ro', isa => 'Num' );
has 'h' => ( is => 'ro', isa => 'HashRef', default => sub { {} } );

no Moose;

__PACKAGE__->meta->make_immutable;

1;

##################################################################################
package main;

use strict;
use warnings;

use Time::HiRes;

my @employee1instances;
my @employee2instances;

######################################### create some data

my $start = [ Time::HiRes::gettimeofday() ];

for my $i ( 1 .. 40000 ) {
    my $e = Employee1->new( ID => $i );
    $e->add_employeedepartment(
                      EmployeeDepartment->new(
                          department => Department->new( ID => $i * 10 + $_ ),
                          percentage => rand(100)
                      )
    ) for ( 1 .. 5 );
    push @employee1instances, $e;
}

my $elapsed = Time::HiRes::tv_interval($start);
print "Employee1 creation elapsed time: $elapsed seconds!\n";

$start = [ Time::HiRes::gettimeofday() ];

for my $i ( 40001 .. 80000 ) {
    my $e = Employee2->new( ID => $i );
    $e->h->{ Department->new( ID => $i * 10 + $_ ) } = rand(100)
        for ( 1 .. 5 );
    push @employee2instances, $e;
}

$elapsed = Time::HiRes::tv_interval($start);
print "Employee2 creation elapsed time: $elapsed seconds!\n";


######################################### getting data back

$start = [ Time::HiRes::gettimeofday() ];

foreach my $e (@employee1instances) {
    my $total = 0;
    foreach my $ed ( $e->all_employeedepartments ) {
        $total += $ed->percentage();
    }

    # print $e->ID." ".$total."\n";
}
$elapsed = Time::HiRes::tv_interval($start);
print "Employee1 retrieve elapsed time: $elapsed seconds!\n";

$start = [ Time::HiRes::gettimeofday() ];

foreach my $e (@employee2instances) {
    my $total = 0;
    foreach my $d ( keys $e->h ) {
        $total += $e->h->{$d};
    }

    # print $e->ID." ".$total."\n";
}

$elapsed = Time::HiRes::tv_interval($start);
print "Employee2 retrieve elapsed time: $elapsed seconds!\n";