private void updateDelta()

in eureka-client/src/main/java/com/netflix/discovery/DiscoveryClient.java [1237:1294]
49 lines of code
13 McCabe index (conditional complexity)

    private void updateDelta(Applications delta) {
        int deltaCount = 0;
        for (Application app : delta.getRegisteredApplications()) {
            for (InstanceInfo instance : app.getInstances()) {
                Applications applications = getApplications();
                String instanceRegion = instanceRegionChecker.getInstanceRegion(instance);
                if (!instanceRegionChecker.isLocalRegion(instanceRegion)) {
                    Applications remoteApps = remoteRegionVsApps.get(instanceRegion);
                    if (null == remoteApps) {
                        remoteApps = new Applications();
                        remoteRegionVsApps.put(instanceRegion, remoteApps);
                    }
                    applications = remoteApps;
                }

                ++deltaCount;
                if (ActionType.ADDED.equals(instance.getActionType())) {
                    Application existingApp = applications.getRegisteredApplications(instance.getAppName());
                    if (existingApp == null) {
                        applications.addApplication(app);
                    }
                    logger.debug("Added instance {} to the existing apps in region {}", instance.getId(), instanceRegion);
                    applications.getRegisteredApplications(instance.getAppName()).addInstance(instance);
                } else if (ActionType.MODIFIED.equals(instance.getActionType())) {
                    Application existingApp = applications.getRegisteredApplications(instance.getAppName());
                    if (existingApp == null) {
                        applications.addApplication(app);
                    }
                    logger.debug("Modified instance {} to the existing apps ", instance.getId());

                    applications.getRegisteredApplications(instance.getAppName()).addInstance(instance);

                } else if (ActionType.DELETED.equals(instance.getActionType())) {
                    Application existingApp = applications.getRegisteredApplications(instance.getAppName());
                    if (existingApp != null) {
                        logger.debug("Deleted instance {} to the existing apps ", instance.getId());
                        existingApp.removeInstance(instance);
                        /*
                         * We find all instance list from application(The status of instance status is not only the status is UP but also other status)
                         * if instance list is empty, we remove the application.
                         */
                        if (existingApp.getInstancesAsIsFromEureka().isEmpty()) {
                            applications.removeApplication(existingApp);
                        }
                    }
                }
            }
        }
        logger.debug("The total number of instances fetched by the delta processor : {}", deltaCount);

        getApplications().setVersion(delta.getVersion());
        getApplications().shuffleInstances(clientConfig.shouldFilterOnlyUpInstances());

        for (Applications applications : remoteRegionVsApps.values()) {
            applications.setVersion(delta.getVersion());
            applications.shuffleInstances(clientConfig.shouldFilterOnlyUpInstances());
        }
    }