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lib/Algorithm/HyperLogLog/PP.pm  view on Meta::CPAN

package Algorithm::HyperLogLog::PP;
use strict;
use warnings;
use 5.008008;
use Carp ();
use Digest::MurmurHash3::PurePerl qw(murmur32);
use constant {
    HLL_HASH_SEED => 313,
    TWO_32        => 4294967296.0,
    NEG_TWO_32    => -4294967296.0,
};

our $VERSION = "0.24";

require Algorithm::HyperLogLog;

{

    package Algorithm::HyperLogLog;
    our @ISA = qw(Algorithm::HyperLogLog::PP);
}

sub new {
    my ( $class, $k ) = @_;

    if ( $k < 4 || $k > 16 ) {
        Carp::croak "Number of ragisters must be in the range [4,16]";
    }

    my $m         = 1 << $k;
    my $registers = [ (0) x $m ];
    my $alpha     = 0;
    if ( $m == 16 ) {
        $alpha = 0.673;
    }
    elsif ( $m == 32 ) {
        $alpha = 0.697;
    }
    elsif ( $m == 64 ) {
        $alpha = 0.709;
    }
    else {
        $alpha = 0.7213 / ( 1.0 + 1.079 / $m );
    }

    my $self = {
        k         => $k,
        m         => $m,
        registers => $registers,
        alphaMM   => $alpha * $m * $m,
    };
    bless $self, $class;
    return $self;
}

sub _new_from_dump {
    my ( $class, $k, $data ) = @_;
    my $self = $class->new($k);
    $self->{registers} = $data;
    return $self;
}

sub _dump_register {
    my $self = shift;
    return $self->{registers};
}

sub register_size {
    my $self = shift;
    return $self->{m};
}

sub add {