Cache::Memcached 1.14 problem

Torsten Foertsch torsten.foertsch at
Sat Apr 8 19:43:57 UTC 2006


I know there are 2 new Perl clients on the way. I am asking if they also 
contain something like this function?

sub get_sock { # (key)
    my Cache::Memcached $self = shift;
    my ($key) = @_;
    return $self->sock_to_host($self->{'_single_sock'}) if 
    return undef unless $self->{'active'};
    my $hv = ref $key ? int($key->[0]) : _hashfunc($key);

    $self->init_buckets() unless $self->{'buckets'};

    my $real_key = ref $key ? $key->[1] : $key;
    my $tries = 0;
    while ($tries++ < 20) {
        my $host = $self->{'buckets'}->[$hv % $self->{'bucketcount'}];
        my $sock = $self->sock_to_host($host);
        return $sock if $sock;
        return undef if $sock->{'no_rehash'};
        $hv += _hashfunc($tries . $real_key);  # stupid, but works
    return undef;

The goal of the while-loop is to find another server if the first main one is 
offline. Unfortunately, this will not always work. Try for example "5000" as 
key and 2 servers. For the key itself and all 20 retries the hash function 
gives an odd number. Hence, it points always to the same (offline) server.

Why not simply loop over all servers if the main one is offline?

Another problem with this code arises when the server that had been offline 
comes online. A value stored in another server is not accessible anymore. It 
would be good if set() would return the server or the hash value so it can be 
passed the next time the value is accessed.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
Url :

More information about the memcached mailing list