Caching

• Tie::File also maintains an internal read cache

• If you try to read the same record twice, it comes from the read cache

        sub _fetch {
          my ($self, $n) = @_;

          # check the record cache
          { my $cached = $self->{cache}->lookup($n);
            return $cached if defined $cached;
          }
          ...
          $self->{cache}->insert($n, $rec) 
            if defined $rec && not $self->{flushing};
          $rec;
        }

• This is supposed to cut down on I/O

• You can limit the amount of memory used for the cache:

        tie @FILE, 'Tie::File', $myfile, memory => 200000000;

• Default: 2 MiB

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Copyright © 2003 M. J. Dominus