use strict;
use warnings;
my @ids       = qw(a b c d e f g h);
my $chosen_id = '';
dbmopen( my %recent_ids, 'recent', 0777 ) || die "$!";

while (1) {
    $chosen_id = @ids[ int( rand(@ids) ) ];
    print "chosen:  $chosen_id\n";
    if ( !defined( $recent_ids{$chosen_id} ) ) { last }
    else { print "problem: $chosen_id is on the recent list, choose again\n" }
}

$recent_ids{$chosen_id} = time();

my $count = 0;

foreach ( sort { $recent_ids{$b} <=> $recent_ids{$a} } ( keys(%recent_ids) ) ) {
    $count++;
    if ( $count > 3 ) {
        print "$_ is the oldest id, remove it\n";
        delete( $recent_ids{$_} );

    }
}
print "hash is now:\n";
while ( my ( $key, $value ) = each(%recent_ids) ) {
    print "$key - $value\n";
}
dbmclose(%recent_ids);