Takes a metric object, a metric name, and a cache dict where it will store
        container_name --> (value, tags) so that _process_limit_metric can compute usage_pct
        it also submit said value and tags as a gauge.

def _process_usage_metric(self, m_name, metric, cache, scraper_config):
        """
        Takes a metric object, a metric name, and a cache dict where it will store
        container_name --> (value, tags) so that _process_limit_metric can compute usage_pct
        it also submit said value and tags as a gauge.
        """
        # track containers that still exist in the cache
        seen_keys = {k: False for k in cache}

        samples = self._sum_values_by_context(metric, self._get_entity_id_if_container_metric)
        for c_id, sample in iteritems(samples):
            c_name = self._get_container_label(sample[self.SAMPLE_LABELS], 'name')
            if not c_name:
                continue
            pod_uid = self._get_pod_uid(sample[self.SAMPLE_LABELS])
            if self.pod_list_utils.is_excluded(c_id, pod_uid):
                continue

            tags = tagger.tag(c_id, tagger.HIGH)
            tags += scraper_config['custom_tags']

            # FIXME we are forced to do that because the Kubelet PodList isn't updated
            # for static pods, see https://github.com/kubernetes/kubernetes/pull/59948
            pod = self._get_pod_by_metric_label(sample[self.SAMPLE_LABELS])
            if pod is not None and is_static_pending_pod(pod):
                tags += tagger.tag('kubernetes_pod://%s' % pod["metadata"]["uid"], tagger.HIGH)
                tags += self._get_kube_container_name(sample[self.SAMPLE_LABELS])
                tags = list(set(tags))

            val = sample[self.SAMPLE_VALUE]
            cache[c_name] = (val, tags)
            seen_keys[c_name] = True
            self.gauge(m_name, val, tags)

        # purge the cache
        for k, seen in iteritems(seen_keys):
            if not seen:
                del cache[k]