public static queryCorrelationId()

in Library/CorrelationIdManager.ts [19:100]
64 lines of code
12 McCabe index (conditional complexity)

    public static queryCorrelationId(config: Config, callback: (correlationId: string) => void) {
        // GET request to `${this.endpointBase}/api/profiles/${this.instrumentationKey}/appId`
        // If it 404s, the iKey is bad and we should give up
        // If it fails otherwise, try again later
        const appIdUrlString = `${config.profileQueryEndpoint}/api/profiles/${config.instrumentationKey}/appId`;

        if (CorrelationIdManager.completedLookups.hasOwnProperty(appIdUrlString)) {
            callback(CorrelationIdManager.completedLookups[appIdUrlString]);
            return;
        } else if (CorrelationIdManager.pendingLookups[appIdUrlString]) {
            CorrelationIdManager.pendingLookups[appIdUrlString].push(callback);
            return;
        }

        CorrelationIdManager.pendingLookups[appIdUrlString] = [callback];

        const fetchAppId = () => {
            if (!CorrelationIdManager.pendingLookups[appIdUrlString]) {
                // This query has been cancelled.
                return;
            }

            const requestOptions = {
                method: 'GET',
                // Ensure this request is not captured by auto-collection.
                // Note: we don't refer to the property in HttpDependencyParser because that would cause a cyclical dependency
                disableAppInsightsAutoCollection: true
            };

            Logging.info(CorrelationIdManager.TAG, requestOptions);
            const req = Util.makeRequest(config, appIdUrlString, requestOptions, (res) => {
                if (res.statusCode === 200) {
                    // Success; extract the appId from the body
                    let appId = "";
                    res.setEncoding("utf-8");
                    res.on('data', (data: any) => {
                        appId += data;
                    });
                    res.on('end', () => {
                        Logging.info(CorrelationIdManager.TAG, appId);
                        const result = CorrelationIdManager.correlationIdPrefix + appId;
                        CorrelationIdManager.completedLookups[appIdUrlString] = result;
                        if (CorrelationIdManager.pendingLookups[appIdUrlString]) {
                            CorrelationIdManager.pendingLookups[appIdUrlString].forEach((cb) => cb(result));
                        }
                        delete CorrelationIdManager.pendingLookups[appIdUrlString];
                    });
                } else if (res.statusCode >= 400 && res.statusCode < 500) {
                    // Not found, probably a bad key. Do not try again.
                    CorrelationIdManager.completedLookups[appIdUrlString] = undefined;
                    delete CorrelationIdManager.pendingLookups[appIdUrlString];
                }
                else {
                    // Keep retrying
                    return;
                }
                // Do not retry
                if (CorrelationIdManager._handle) {
                    clearTimeout(CorrelationIdManager._handle);
                    CorrelationIdManager._handle = undefined;
                }
            }, true, false);
            if (req) {
                req.on('error', (error: Error) => {
                    // Unable to contact endpoint.
                    // Do nothing for now.
                    Logging.warn(CorrelationIdManager.TAG, error);
                    if (this._handle) {
                        clearTimeout(CorrelationIdManager._handle);
                        CorrelationIdManager._handle = undefined;
                    }
                });
                req.end();
            }
        };
        if (!CorrelationIdManager._handle) {
            CorrelationIdManager._handle = <any>setTimeout(fetchAppId, config.correlationIdRetryIntervalMs);
            CorrelationIdManager._handle.unref(); // Don't block apps from terminating
        }
        // Initial fetch
        setImmediate(fetchAppId);
    }