@Override
          public void gotData(String k, int flags, long cas, byte[] data) {
            assert k.equals(key) : "Wrong key returned";
            val =
                new CASValue<T>(cas, tc.decode(new CachedData(flags, data,
                    tc.getMaxSize())));
          }
Get the given key to reset its expiration time.

@param key the key to fetch
@param exp the new expiration to set for the given key
@param tc the transcoder to serialize and unserialize value
@return a future that will hold the return value of the fetch
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/MemcachedClient.java