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