@Override
      public void complete() {
        latch.countDown();
        rv.signalComplete();
      }
Gets (with CAS support) the given key asynchronously.

@param <T>
@param key the key to fetch
@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