sub get {
    my ($self, $key) = @_;
    
    $key = $self->sanitize_key($key);

    my $dbh = $self->{server}->{modules}->{$self->{db}};
    my $memh = $self->{server}->{modules}->{$self->{memcache}};

   # Try memcached first
    my $dataref = $memh->get($key);
    if(defined($dataref)) {
        return Maplat::Helpers::DBSerialize::dbthaw($dataref);
    }

   # Ok, try DB
   my $sth = $dbh->prepare_cached("SELECT yamldata FROM memcachedb WHERE mckey = ?")
         or croak($dbh->errstr);
   $sth->execute($key) or croak($dbh->errstr);
   while((my @line = $sth->fetchrow_array)) {
      $dataref = $line[0];
      last;
   }
   $sth->finish;
   $dbh->rollback;

   # Ok, now also store data in memcached
   if(defined($dataref)) {
      $memh->set($key, $dataref);
      return Maplat::Helpers::DBSerialize::dbthaw($dataref);
   }

   return;
}

sub set { ## no critic (NamingConventions::ProhibitAmbiguousNames)
    my ($self, $key, $data) = @_;

    $key = $self->sanitize_key($key);
    my $dbh = $self->{server}->{modules}->{$self->{db}};
    my $memh = $self->{server}->{modules}->{$self->{memcache}};

    my $yamldata = Maplat::Helpers::DBSerialize::dbfreeze($data);

    # Check if it already matches the key we have
    my $olddata = $memh->get($key);
    if(defined($olddata) && $olddata eq $yamldata) {
        return 1;
    }
 
    $memh->set($key, $yamldata);   
       
    my $sth = $dbh->prepare_cached("SELECT merge_memcachedb(?, ?)")
            or return;
    my $count = 0;
    my $ok = 0;
    while($count < $RETRY_COUNT) {
        # print STDERR "WORKER: Merge $key\n";
        if($sth->execute($key, $yamldata)) {
            $ok = 1;
            $sth->finish;
            $dbh->commit;
            last;
        } else {
            $count++;
            $sth->finish;
            $dbh->rollback;
            if($count < $RETRY_COUNT) {
                sleep($RETRY_WAIT); # try again in a short time
            }
        }
    }
    if(!$ok) {
        croak($dbh->errstr);
    }
    
    return 1;
}