Method to test if cache contains the data that
            the particle needs

def need_data(self, i):
        """
            Method to test if cache contains the data that
            the particle needs
        """

        # If we are not caching, we always grab data from the raw source
        if self.caching is False:
            return False

        logger.debug("Checking cache for data availability at %s." % self.part.location.logstring())

        try:
            # Tell the DataController that we are going to be reading from the file
            with self.read_lock:
                self.read_count.value += 1
                self.has_read_lock.append(os.getpid())

            self.dataset.opennc()
            # Test if the cache has the data we need
            # If the point we request contains fill values,
            # we need data
            cached_lookup = self.dataset.get_values('domain', timeinds=[np.asarray([i])], point=self.part.location)
            logger.debug("Type of result: %s" % type(cached_lookup))
            logger.debug("Double mean of result: %s" % np.mean(np.mean(cached_lookup)))
            logger.debug("Type of Double mean of result: %s" % type(np.mean(np.mean(cached_lookup))))
            if type(np.mean(np.mean(cached_lookup))) == np.ma.core.MaskedConstant:
                need = True
                logger.debug("I NEED data.  Got back: %s" % cached_lookup)
            else:
                need = False
                logger.debug("I DO NOT NEED data")
        except StandardError:
            # If the time index doesnt even exist, we need
            need = True
            logger.debug("I NEED data (no time index exists in cache)")
        finally:
            self.dataset.closenc()
            with self.read_lock:
                self.read_count.value -= 1
                self.has_read_lock.remove(os.getpid())

        return need