Examples with ClusterView org.apache.sling.discovery.ClusterView used on opensource projects

Example 16 with ClusterView

use of org.apache.sling.discovery.ClusterView in project sling by apache.

the class TopologyWebConsolePlugin method printConfiguration.

public void printConfiguration(final PrintWriter pw) {
    final TopologyView topology = this.currentView;
    pw.println(TITLE);
    pw.println("---------------------------------------");
    pw.println();
    if (topology == null) {
        pw.println("No topology available yet!");
        return;
    }
    pw.print("Topology");
    if (!topology.isCurrent()) {
        pw.print(" CHANGING! (the view is no longer current!)");
    }
    pw.println();
    pw.println();
    final Set<ClusterView> clusters = topology.getClusterViews();
    final ClusterView myCluster = topology.getLocalInstance().getClusterView();
    printCluster(pw, myCluster, myCluster);
    for (Iterator<ClusterView> it = clusters.iterator(); it.hasNext(); ) {
        ClusterView clusterView = it.next();
        if (clusterView.equals(myCluster)) {
            // skip - I already rendered that
            continue;
        }
        printCluster(pw, clusterView, myCluster);
    }
    pw.println();
    pw.println();
    final Collection<CachedAnnouncement> incomingConnections = announcementRegistry.listLocalIncomingAnnouncements();
    if (incomingConnections.size() > 0) {
        pw.println("Incoming topology connectors");
        pw.println("---------------------------------------");
        for (final CachedAnnouncement incomingCachedAnnouncement : incomingConnections) {
            Announcement incomingAnnouncement = incomingCachedAnnouncement.getAnnouncement();
            pw.print("Owner Sling Id : ");
            pw.print(incomingAnnouncement.getOwnerId());
            pw.println();
            if (incomingAnnouncement.getServerInfo() != null) {
                pw.print("Server Info : ");
                pw.print(incomingAnnouncement.getServerInfo());
                pw.println();
            }
            pw.println("Last heartbeat received : " + beautifiedTimeDiff(incomingCachedAnnouncement.getLastPing()));
            pw.println("Timeout : " + beautifiedDueTime(incomingCachedAnnouncement.getSecondsUntilTimeout()));
            pw.println();
        }
        pw.println();
        pw.println();
    }
    final Collection<TopologyConnectorClientInformation> outgoingConnections = connectorRegistry.listOutgoingConnectors();
    if (outgoingConnections.size() > 0) {
        pw.println("Outgoing topology connectors");
        pw.println("---------------------------------------");
        for (final TopologyConnectorClientInformation topologyConnectorClient : outgoingConnections) {
            final String remoteSlingId = topologyConnectorClient.getRemoteSlingId();
            final boolean autoStopped = topologyConnectorClient.isAutoStopped();
            final boolean isConnected = topologyConnectorClient.isConnected() && remoteSlingId != null;
            pw.print("Connector URL : ");
            pw.print(topologyConnectorClient.getConnectorUrl());
            pw.println();
            if (autoStopped) {
                pw.println("Conncted to Sling Id : auto-stopped");
                pw.println("Connector status : auto-stopped due to local-loop");
            } else if (isConnected && !topologyConnectorClient.representsLoop()) {
                pw.print("Connected to Sling Id : ");
                pw.println(remoteSlingId);
                pw.println("Connector status : ok, in use");
            } else if (topologyConnectorClient.representsLoop()) {
                pw.print("Connected to Sling Id : ");
                pw.println(remoteSlingId);
                pw.println("Connector status : ok, unused (loop or duplicate): standby");
            } else {
                final int statusCode = topologyConnectorClient.getStatusCode();
                final String statusDetails = topologyConnectorClient.getStatusDetails();
                final String tooltipText;
                switch(statusCode) {
                    case HttpServletResponse.SC_UNAUTHORIZED:
                        tooltipText = HttpServletResponse.SC_UNAUTHORIZED + ": possible setup issue of discovery.oak on target instance, or wrong URL";
                        break;
                    case HttpServletResponse.SC_NOT_FOUND:
                        tooltipText = HttpServletResponse.SC_NOT_FOUND + ": possible white list rejection by target instance";
                        break;
                    case -1:
                        tooltipText = "-1: check error log. possible connection refused.";
                        break;
                    default:
                        tooltipText = null;
                }
                pw.println("Connected to Sling Id : not connected");
                pw.print("Connector status : not ok");
                if (tooltipText != null) {
                    pw.print(" (");
                    pw.print(tooltipText);
                    pw.print(")");
                }
                pw.print(" (HTTP StatusCode: " + statusCode + ", " + statusDetails + ")");
                pw.println();
                pw.println("Last heartbeat sent : " + beautifiedTimeDiff(topologyConnectorClient.getLastPingSent()));
                pw.println("Next heartbeat due : " + beautifiedDueTime(topologyConnectorClient.getNextPingDue()));
            }
            pw.println();
        }
        pw.println();
        pw.println();
    }
    if (topologyLog.size() > 0) {
        pw.println("Topology Change History");
        pw.println("---------------------------------------");
        for (final String aLogEntry : topologyLog) {
            pw.println(aLogEntry);
        }
        pw.println();
        pw.println();
    }
    if (propertyChangeLog.size() > 0) {
        pw.println("Property Change History");
        pw.println("---------------------------------------");
        for (final String aLogEntry : propertyChangeLog) {
            pw.println(aLogEntry);
        }
        pw.println();
    }
    pw.println("Oak Discovery-Lite Descriptor History");
    pw.println("---------------------------------------");
    updateDiscoveryLiteHistory();
    for (String discoLiteHistoryEntry : discoveryLiteHistory) {
        pw.println(discoLiteHistoryEntry);
    }
    pw.println();
    pw.println();
    pw.println("ClusterSyncService History");
    pw.println("---------------------------------------");
    for (String syncHistoryEntry : clusterSyncService.getSyncHistory()) {
        pw.println(syncHistoryEntry);
    }
    pw.println();
    pw.println();
}

Example 17 with ClusterView

use of org.apache.sling.discovery.ClusterView in project sling by apache.

the class TopologyWebConsolePlugin method handleTopologyEvent.

/**
     * keep a truncated history of the log events for information purpose (to be shown in the webconsole)
     */
@Override
public void handleTopologyEvent(final TopologyEvent event) {
    if (event.getType() == Type.PROPERTIES_CHANGED) {
        this.currentView = event.getNewView();
        StringBuilder sb = new StringBuilder();
        InstancesDiff instanceDiff = new InstancesDiff(event.getOldView(), event.getNewView());
        // there shouldn't be any instances added, but for paranoia reason:
        Collection<InstanceDescription> added = instanceDiff.added().get();
        if (!added.isEmpty()) {
            sb.append("instances were added:");
            for (InstanceDescription instance : added) {
                sb.append(" ");
                sb.append(instance.getSlingId());
            }
            sb.append(".");
        }
        // there shouldn't be any instances removed as well, but again for paranoia reason:
        Collection<InstanceDescription> removed = instanceDiff.removed().get();
        if (!removed.isEmpty()) {
            sb.append("instances were removed:");
            for (InstanceDescription instance : added) {
                sb.append(" ");
                sb.append(instance.getSlingId());
            }
            sb.append(".");
        }
        Set<InstanceDescription> newInstances = event.getNewView().getInstances();
        for (Iterator<InstanceDescription> it = newInstances.iterator(); it.hasNext(); ) {
            final InstanceDescription newInstanceDescription = it.next();
            InstanceDescription oldInstanceDescription = findInstance(event.getOldView(), newInstanceDescription.getSlingId());
            if (oldInstanceDescription == null) {
                logger.error("handleTopologyEvent: got a property changed but did not find instance " + newInstanceDescription + " in oldview.. event=" + event);
                sb.append("did not find instance in old view: " + newInstanceDescription.getSlingId() + ".");
                continue;
            }
            Map<String, String> oldProps = oldInstanceDescription.getProperties();
            Map<String, String> newProps = newInstanceDescription.getProperties();
            StringBuilder diff = diff(oldProps, newProps);
            if (diff.length() > 0) {
                if (sb.length() != 0) {
                    sb.append(", ");
                }
                sb.append("on instance " + newInstanceDescription.getSlingId() + (newInstanceDescription.isLeader() ? " [isLeader]" : "") + ": " + diff + ". ");
            }
        }
        addEventLog(event.getType(), "details: " + sb.toString());
    } else if (event.getType() == Type.TOPOLOGY_INIT) {
        this.currentView = event.getNewView();
        StringBuilder details = new StringBuilder();
        for (Iterator<InstanceDescription> it = event.getNewView().getInstances().iterator(); it.hasNext(); ) {
            InstanceDescription newInstance = it.next();
            if (details.length() != 0) {
                details.append(", ");
            }
            details.append(newInstance.getSlingId());
            if (newInstance.isLeader()) {
                details.append(" [isLeader]");
            }
        }
        addEventLog(event.getType(), "view: " + shortViewInfo(event.getNewView()) + ". " + details);
    } else if (event.getType() == Type.TOPOLOGY_CHANGING) {
        this.currentView = event.getOldView();
        addEventLog(event.getType(), "old view: " + shortViewInfo(event.getOldView()));
    } else {
        this.currentView = event.getNewView();
        if (event.getOldView() == null) {
            addEventLog(event.getType(), "new view: " + shortViewInfo(event.getNewView()));
        } else {
            StringBuilder details = new StringBuilder();
            for (Iterator<InstanceDescription> it = event.getNewView().getInstances().iterator(); it.hasNext(); ) {
                InstanceDescription newInstance = it.next();
                if (findInstance(event.getOldView(), newInstance.getSlingId()) == null) {
                    if (details.length() != 0) {
                        details.append(", ");
                    }
                    details.append(newInstance.getSlingId() + " joined");
                }
            }
            for (Iterator<InstanceDescription> it = event.getOldView().getInstances().iterator(); it.hasNext(); ) {
                InstanceDescription oldInstance = it.next();
                if (findInstance(event.getNewView(), oldInstance.getSlingId()) == null) {
                    if (details.length() != 0) {
                        details.append(", ");
                    }
                    details.append(oldInstance.getSlingId() + " left");
                }
            }
            final InstanceDescription li = event.getNewView().getLocalInstance();
            if (li != null) {
                ClusterView clusterView = li.getClusterView();
                if (clusterView != null) {
                    final InstanceDescription leader = clusterView.getLeader();
                    if (leader != null) {
                        if (details.length() != 0) {
                            details.append(", ");
                        }
                        details.append("[isLeader: " + leader.getSlingId() + "]");
                    }
                }
            }
            addEventLog(event.getType(), "old view: " + shortViewInfo(event.getOldView()) + ", new view: " + shortViewInfo(event.getNewView()) + ". " + details);
        }
    }
    updateDiscoveryLiteHistory();
}

Example 18 with ClusterView

use of org.apache.sling.discovery.ClusterView in project sling by apache.

the class TopologyConnectorClient method ping.

/** ping the server and pass the announcements between the two **/
void ping(final boolean force) {
    if (autoStopped) {
        // then we suppress any further pings!
        logger.debug("ping: autoStopped=true, hence suppressing any further pings.");
        return;
    }
    if (force) {
        backoffPeriodEnd = -1;
    } else if (backoffPeriodEnd > 0) {
        if (System.currentTimeMillis() < backoffPeriodEnd) {
            logger.debug("ping: not issueing a heartbeat due to backoff instruction from peer.");
            return;
        } else {
            logger.debug("ping: backoff period ended, issuing another ping now.");
        }
    }
    final String uri = connectorUrl.toString() + "." + clusterViewService.getSlingId() + ".json";
    if (logger.isDebugEnabled()) {
        logger.debug("ping: connectorUrl=" + connectorUrl + ", complete uri=" + uri);
    }
    final HttpClientContext clientContext = HttpClientContext.create();
    final CloseableHttpClient httpClient = createHttpClient();
    final HttpPut putRequest = new HttpPut(uri);
    // setting the connection timeout (idle connection, configured in seconds)
    putRequest.setConfig(RequestConfig.custom().setConnectTimeout(1000 * config.getSocketConnectTimeout()).build());
    Announcement resultingAnnouncement = null;
    try {
        String userInfo = connectorUrl.getUserInfo();
        if (userInfo != null) {
            Credentials c = new UsernamePasswordCredentials(userInfo);
            clientContext.getCredentialsProvider().setCredentials(new AuthScope(putRequest.getURI().getHost(), putRequest.getURI().getPort()), c);
        }
        Announcement topologyAnnouncement = new Announcement(clusterViewService.getSlingId());
        topologyAnnouncement.setServerInfo(serverInfo);
        final ClusterView clusterView;
        try {
            clusterView = clusterViewService.getLocalClusterView();
        } catch (UndefinedClusterViewException e) {
            // SLING-5030 : then we cannot ping
            logger.warn("ping: no clusterView available at the moment, cannot ping others now: " + e);
            return;
        }
        topologyAnnouncement.setLocalCluster(clusterView);
        if (force) {
            logger.debug("ping: sending a resetBackoff");
            topologyAnnouncement.setResetBackoff(true);
        }
        announcementRegistry.addAllExcept(topologyAnnouncement, clusterView, new AnnouncementFilter() {

            public boolean accept(final String receivingSlingId, final Announcement announcement) {
                // filter out announcements that are of old cluster instances
                // which I dont really have in my cluster view at the moment
                final Iterator<InstanceDescription> it = clusterView.getInstances().iterator();
                while (it.hasNext()) {
                    final InstanceDescription instance = it.next();
                    if (instance.getSlingId().equals(receivingSlingId)) {
                        // all fine then
                        return true;
                    }
                }
                // then I should also not propagate that announcement anywhere
                return false;
            }
        });
        final String p = requestValidator.encodeMessage(topologyAnnouncement.asJSON());
        if (logger.isDebugEnabled()) {
            logger.debug("ping: topologyAnnouncement json is: " + p);
        }
        requestValidator.trustMessage(putRequest, p);
        if (config.isGzipConnectorRequestsEnabled()) {
            // tell the server that the content is gzipped:
            putRequest.addHeader("Content-Encoding", "gzip");
            // and gzip the body:
            final ByteArrayOutputStream baos = new ByteArrayOutputStream();
            final GZIPOutputStream gzipOut = new GZIPOutputStream(baos);
            gzipOut.write(p.getBytes("UTF-8"));
            gzipOut.close();
            final byte[] gzippedEncodedJson = baos.toByteArray();
            putRequest.setEntity(new ByteArrayEntity(gzippedEncodedJson, ContentType.APPLICATION_JSON));
            lastRequestEncoding = "gzip";
        } else {
            // otherwise plaintext:
            final StringEntity plaintext = new StringEntity(p, "UTF-8");
            plaintext.setContentType(ContentType.APPLICATION_JSON.getMimeType());
            putRequest.setEntity(plaintext);
            lastRequestEncoding = "plaintext";
        }
        // independent of request-gzipping, we do accept the response to be gzipped,
        // so indicate this to the server:
        putRequest.addHeader("Accept-Encoding", "gzip");
        final CloseableHttpResponse response = httpClient.execute(putRequest, clientContext);
        if (logger.isDebugEnabled()) {
            logger.debug("ping: done. code=" + response.getStatusLine().getStatusCode() + " - " + response.getStatusLine().getReasonPhrase());
        }
        lastStatusCode = response.getStatusLine().getStatusCode();
        lastResponseEncoding = null;
        if (response.getStatusLine().getStatusCode() == HttpServletResponse.SC_OK) {
            final Header contentEncoding = response.getFirstHeader("Content-Encoding");
            if (contentEncoding != null && contentEncoding.getValue() != null && contentEncoding.getValue().contains("gzip")) {
                lastResponseEncoding = "gzip";
            } else {
                lastResponseEncoding = "plaintext";
            }
            // limiting to 16MB, should be way enough
            final String responseBody = requestValidator.decodeMessage(putRequest.getURI().getPath(), response);
            if (logger.isDebugEnabled()) {
                logger.debug("ping: response body=" + responseBody);
            }
            if (responseBody != null && responseBody.length() > 0) {
                Announcement inheritedAnnouncement = Announcement.fromJSON(responseBody);
                final long backoffInterval = inheritedAnnouncement.getBackoffInterval();
                if (backoffInterval > 0) {
                    // then reset the backoffPeriodEnd:
                    /* minus 1 sec to avoid slipping the interval by a few millis */
                    this.backoffPeriodEnd = System.currentTimeMillis() + (1000 * backoffInterval) - 1000;
                    logger.debug("ping: servlet instructed to backoff: backoffInterval=" + backoffInterval + ", resulting in period end of " + new Date(backoffPeriodEnd));
                } else {
                    logger.debug("ping: servlet did not instruct any backoff-ing at this stage");
                    this.backoffPeriodEnd = -1;
                }
                if (inheritedAnnouncement.isLoop()) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("ping: connector response indicated a loop detected. not registering this announcement from " + inheritedAnnouncement.getOwnerId());
                    }
                    if (inheritedAnnouncement.getOwnerId().equals(clusterViewService.getSlingId())) {
                        if (config.isAutoStopLocalLoopEnabled()) {
                            // results in connected -> false and representsloop -> true
                            inheritedAnnouncement = null;
                            // results in isAutoStopped -> true
                            autoStopped = true;
                        }
                    }
                } else {
                    inheritedAnnouncement.setInherited(true);
                    if (announcementRegistry.registerAnnouncement(inheritedAnnouncement) == -1) {
                        if (logger.isDebugEnabled()) {
                            logger.debug("ping: connector response is from an instance which I already see in my topology" + inheritedAnnouncement);
                        }
                        statusDetails = "receiving side is seeing me via another path (connector or cluster) already (loop)";
                        return;
                    }
                }
                resultingAnnouncement = inheritedAnnouncement;
                statusDetails = null;
            } else {
                statusDetails = "no response body received";
            }
        } else {
            statusDetails = "got HTTP Status-Code: " + lastStatusCode;
        }
        // SLING-2882 : reset suppressPingWarnings_ flag in success case
        suppressPingWarnings_ = false;
    } catch (IOException e) {
        // SLING-2882 : set/check the suppressPingWarnings_ flag
        if (suppressPingWarnings_) {
            if (logger.isDebugEnabled()) {
                logger.debug("ping: got IOException: " + e + ", uri=" + uri);
            }
        } else {
            suppressPingWarnings_ = true;
            logger.warn("ping: got IOException [suppressing further warns]: " + e + ", uri=" + uri);
        }
        statusDetails = e.toString();
    } catch (JsonException e) {
        logger.warn("ping: got JSONException: " + e);
        statusDetails = e.toString();
    } catch (RuntimeException re) {
        logger.warn("ping: got RuntimeException: " + re, re);
        statusDetails = re.toString();
    } finally {
        putRequest.releaseConnection();
        lastInheritedAnnouncement = resultingAnnouncement;
        lastPingedAt = System.currentTimeMillis();
        try {
            httpClient.close();
        } catch (IOException e) {
            logger.error("disconnect: could not close httpClient: " + e, e);
        }
    }
}

Example 19 with ClusterView

use of org.apache.sling.discovery.ClusterView in project sling by apache.

the class TopologyConnectorServlet method doPut.

@Override
protected void doPut(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    if (!isWhitelisted(request)) {
        // in theory it would be 403==forbidden, but that would reveal that
        // a resource would exist there in the first place
        response.sendError(HttpServletResponse.SC_NOT_FOUND);
        return;
    }
    final String[] pathInfo = request.getPathInfo().split("\\.");
    final String extension = pathInfo.length == 3 ? pathInfo[2] : "";
    if (!"json".equals(extension)) {
        response.sendError(HttpServletResponse.SC_NOT_FOUND);
        return;
    }
    final String selector = pathInfo.length == 3 ? pathInfo[1] : "";
    String topologyAnnouncementJSON = requestValidator.decodeMessage(request);
    if (logger.isDebugEnabled()) {
        logger.debug("doPost: incoming topology announcement is: " + topologyAnnouncementJSON);
    }
    final Announcement incomingTopologyAnnouncement;
    try {
        incomingTopologyAnnouncement = Announcement.fromJSON(topologyAnnouncementJSON);
        if (!incomingTopologyAnnouncement.getOwnerId().equals(selector)) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return;
        }
        String slingId = clusterViewService.getSlingId();
        if (slingId == null) {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            logger.info("doPut: no slingId available. Service not ready as expected at the moment.");
            return;
        }
        incomingTopologyAnnouncement.removeInherited(slingId);
        final Announcement replyAnnouncement = new Announcement(slingId);
        long backoffInterval = -1;
        ClusterView clusterView = clusterViewService.getLocalClusterView();
        if (!incomingTopologyAnnouncement.isCorrectVersion()) {
            logger.warn("doPost: rejecting an announcement from an incompatible connector protocol version: " + incomingTopologyAnnouncement);
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return;
        } else if (ClusterViewHelper.contains(clusterView, incomingTopologyAnnouncement.getOwnerId())) {
            if (logger.isDebugEnabled()) {
                logger.debug("doPost: rejecting an announcement from an instance that is part of my cluster: " + incomingTopologyAnnouncement);
            }
            // marking as 'loop'
            replyAnnouncement.setLoop(true);
            backoffInterval = config.getBackoffStandbyInterval();
        } else if (ClusterViewHelper.containsAny(clusterView, incomingTopologyAnnouncement.listInstances())) {
            if (logger.isDebugEnabled()) {
                logger.debug("doPost: rejecting an announcement as it contains instance(s) that is/are part of my cluster: " + incomingTopologyAnnouncement);
            }
            // marking as 'loop'
            replyAnnouncement.setLoop(true);
            backoffInterval = config.getBackoffStandbyInterval();
        } else {
            backoffInterval = announcementRegistry.registerAnnouncement(incomingTopologyAnnouncement);
            if (logger.isDebugEnabled()) {
                logger.debug("doPost: backoffInterval after registration: " + backoffInterval);
            }
            if (backoffInterval == -1) {
                if (logger.isDebugEnabled()) {
                    logger.debug("doPost: rejecting an announcement from an instance that I already see in my topology: " + incomingTopologyAnnouncement);
                }
                // marking as 'loop'
                replyAnnouncement.setLoop(true);
                backoffInterval = config.getBackoffStandbyInterval();
            } else {
                // normal, successful case: replying with the part of the topology which this instance sees
                replyAnnouncement.setLocalCluster(clusterView);
                announcementRegistry.addAllExcept(replyAnnouncement, clusterView, new AnnouncementFilter() {

                    public boolean accept(final String receivingSlingId, Announcement announcement) {
                        if (announcement.getPrimaryKey().equals(incomingTopologyAnnouncement.getPrimaryKey())) {
                            return false;
                        }
                        return true;
                    }
                });
            }
        }
        if (backoffInterval > 0) {
            replyAnnouncement.setBackoffInterval(backoffInterval);
            if (logger.isDebugEnabled()) {
                logger.debug("doPost: backoffInterval for client set to " + replyAnnouncement.getBackoffInterval());
            }
        }
        final String p = requestValidator.encodeMessage(replyAnnouncement.asJSON());
        requestValidator.trustMessage(response, request, p);
        // gzip the response if the client accepts this
        final String acceptEncodingHeader = request.getHeader("Accept-Encoding");
        if (acceptEncodingHeader != null && acceptEncodingHeader.contains("gzip")) {
            // tell the client that the content is gzipped:
            response.setHeader("Content-Encoding", "gzip");
            // then gzip the body
            final GZIPOutputStream gzipOut = new GZIPOutputStream(response.getOutputStream());
            gzipOut.write(p.getBytes("UTF-8"));
            gzipOut.close();
        } else {
            // otherwise plaintext
            final PrintWriter pw = response.getWriter();
            pw.print(p);
            pw.flush();
        }
    } catch (JsonException e) {
        logger.error("doPost: Got a JSONException: " + e, e);
        response.sendError(500);
    } catch (UndefinedClusterViewException e) {
        logger.warn("doPost: no clusterView available at the moment - cannot handle connectors now: " + e);
        // "please retry, but atm I can't help since I'm isolated"
        response.sendError(503);
    }
}

Example 20 with ClusterView

use of org.apache.sling.discovery.ClusterView in project sling by apache.

the class DefaultTopologyView method toString.

@Override
public String toString() {
    StringBuilder sb = new StringBuilder();
    try {
        boolean firstCluster = true;
        for (ClusterView clusterView : getClusterViews()) {
            if (!firstCluster) {
                sb.append(", ");
            }
            firstCluster = false;
            sb.append("[clusterId=" + clusterView.getId() + ", instances=");
            boolean firstInstance = true;
            for (InstanceDescription id : clusterView.getInstances()) {
                if (!firstInstance) {
                    sb.append(", ");
                }
                firstInstance = false;
                sb.append("[id=" + id.getSlingId() + ", isLeader=" + id.isLeader() + ", isLocal=" + id.isLocal() + "]");
            }
            sb.append("]");
        }
    } catch (Exception e) {
        // paranoia fallback
        sb = new StringBuilder(instances.toString());
    }
    return "DefaultTopologyView[current=" + isCurrent() + ", num=" + instances.size() + ", instances=" + sb + "]";
}