@Override
  public <T> OperationFuture<Boolean> touch(final String key, final int exp) {
    return touch(key, exp, transcoder);
  }
Touch the given key to reset its expiration time with the default
transcoder.

@param key the key to fetch
@param exp the new expiration to set for the given key
@return a future that will hold the return value of whether or not the
        fetch succeeded
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/MemcachedClient.java