Question

I’m writing a script that parses the “pure-ftpwho -s” command to get a list of the current transfers. But when a user disconnects from the FTP and reconnects back and resumes a transfer, the file shows up twice. I want to remove the ghosted one with Perl. After parsing, here is what the arrayref looks like (dumped with Data::Dumper)

$VAR1 = [
      {
        'status' => 'DL',
        'percent' => '20',
        'speed' => '10',
        'file' => 'somefile.txt',
        'user' => 'user1',
        'size' => '14648'
      },
      {
        'status' => 'DL',
        'percent' => '63',
        'speed' => '11',
        'file' => 'somefile.txt',
        'user' => 'user1',
        'size' => '14648'
      },
      {
        'status' => 'DL',
        'percent' => '16',
        'speed' => '60',
        'file' => 'somefile.txt',
        'user' => 'user2',
        'size' => '14648'
      }
    ];

Here user1 and user2 are downloading the same file, but user1 appears twice because the first one is a “ghost”. What’s the best way to check and remove elements that I don’t need (in this case the first element of the arrayref). The condition to check is that – If the “file” key and “user” key is the same, then delete the hashref that contains the smaller value of “percent” key (if they’re the same then delete all except one).

Answer 1

If order in the original arrayref doesn’t matter, this should work:

my %users;
my @result;

for my $data (@$arrayref) {
    push @{ $users{$data->{user}.$data->{file}} }, $data;
}

for my $value (values %users) {
    my @data = sort { $a->{percent} <=> $b->{percent} } @$value;
    push @result, $data[-1];
}

This can definitely be improved for efficiency.