Unless I'm reading the code wrong, a scan() will call expiry_due() to see if an expire run needs to happen.  It looks at the ntokens entry in the database, and if runs if ntokens > min_size (which doesn't make any sense since we'd expire back to min_size, and we'd then start expiring every scan()), it'll expire.

However, ntokens only ever gets updated when an expire is done.  So an expire never actually occurs unless it's forced.

Or am I missing something?

My suggested change would be to make tok_put:

sub tok_put {
  my ($self, $tok, $ts, $th, $atime) = @_;
  $ts ||= 0;
  $th ||= 0;
  if ($ts == 0 && $th == 0) {
    delete $self->{db_toks}->{$tok};
    $self->{db_toks}->{$NTOKENS_MAGIC_TOKEN}--;
  } else {
    if ( !exists $self->{db_toks}->{$tok} ) {
      $self->{db_toks}->{$NTOKENS_MAGIC_TOKEN}++;
    }
    $self->{db_toks}->{$tok} = tok_pack ($ts, $th, $atime);
  }
}


I added the sections for $NTOKENS_MAGIC_TOKEN.   Thoughts?  I'd do up a suggested patch, but I have to head out to a doctor's appointment. :|