// Save listing...
	go func() {
		if err := saver.saveMetaCacheStream(listCtx, &meta, saveCh); err != nil {
			meta.setErr(err.Error())
		}
		cancel()
	}()

	// Do listing...
	go func(o listPathOptions) {
		err := z.listMerged(listCtx, o, inCh)
		if err != nil {
			meta.setErr(err.Error())
		}
		o.debugln("listAndSave: listing", o.ID, "finished with ", err)
	}(*o)

	cancel context.CancelFunc
}

func (m *metaCacheRPC) setErr(err string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	meta := *m.meta
	if meta.status != scanStateError {
		meta.error = err
		meta.status = scanStateError
	} else {
		// An error is already set.
		return
	}
	meta, _ = m.o.updateMetacacheListing(meta, m.rpc)
	*m.meta = meta
}

// getErr will return an error if the listing failed.

        final Set<String> urlSet = new HashSet<>();
        final List<UrlQueue<?>> childList = childUrlList.stream().filter(d -> StringUtil.isNotBlank(d.getUrl())
                && urlSet.add(d.getUrl() + "\n" + d.getMetaData()) && crawlerContext.getUrlFilter().match(d.getUrl())).map(d -> {
                    final UrlQueue<?> uq = crawlerContainer.getComponent("urlQueue");
                    uq.setCreateTime(SystemUtil.currentTimeMillis());

            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(accessResult.getUrl() + " already exists.");
            }
            arMap.put(accessResult.getUrl(), accessResult);
        }

    }

    /*
     * (non-Javadoc)
     *

        assertEquals(Constants.GET_METHOD, testListener.requestMethod);
        assertNull(testListener.exceptionUrl);
        assertEquals(1, testClient.count);
        assertEquals(url, response.getUrl());
        assertEquals(Constants.GET_METHOD, response.getMethod());
    }

    public void test_doGet_with4Exception() {
        final FaultTolerantClient client = new FaultTolerantClient();

        final Set<String> urlSet = new HashSet<>();
        final List<UrlQueue<?>> childList = childUrlList.stream().filter(d -> StringUtil.isNotBlank(d.getUrl())
                && urlSet.add(d.getUrl() + "\n" + d.getMetaData()) && crawlerContext.urlFilter.match(d.getUrl())).map(d -> {
                    final UrlQueue<?> uq = crawlerContainer.getComponent("urlQueue");
                    uq.setCreateTime(SystemUtil.currentTimeMillis());

                assertTrue(urlQueue.getUrl() + "=>" + url1, urlQueue.getUrl().startsWith(url1));
            }
            while ((urlQueue = urlQueueService.poll(sessionId2)) != null) {
                assertTrue(urlQueue.getUrl() + "=>" + url2, urlQueue.getUrl().startsWith(url2));
            }

            dataService.iterate(sessionId1, accessResult -> assertTrue(accessResult.getUrl().startsWith(url1)));

				retErr = err
				healingLogIf(ctx, err)
				continue
			}
			// Check if bucket is object locked.
			lr, err = globalBucketObjectLockSys.Get(bucket)
			if err != nil {
				retErr = err
				healingLogIf(ctx, err)
				continue
			}
			rcfg, err = getReplicationConfig(ctx, bucket)
			if err != nil {
				retErr = err
				healingLogIf(ctx, err)
				continue

                && isValidCanonicalUrl(responseData.getUrl(), canonicalUrl)) {
            final Set<RequestData> childUrlSet = new HashSet<>();
            childUrlSet.add(RequestDataBuilder.newRequestData().get().url(canonicalUrl).build());
            logger.info("CANONICAL: {} -> {}", responseData.getUrl(), canonicalUrl);

            logger.debug("Crawling Access Exception at {}", urlQueue.getUrl(), e);
        } else if (e.isInfoEnabled()) {
            logger.info(e.getMessage());
        } else if (e.isWarnEnabled()) {
            logger.warn("Crawling Access Exception at " + urlQueue.getUrl(), e);
        } else if (e.isErrorEnabled()) {
            logger.error("Crawling Access Exception at " + urlQueue.getUrl(), e);
        }
    }