public Segment preFilter()

in aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/jakarta/servlet/AWSXRayServletFilter.java [315:411]
81 lines of code
21 McCabe index (conditional complexity)

    public Segment preFilter(ServletRequest request, ServletResponse response) {
        AWSXRayRecorder recorder = getRecorder();
        HttpServletRequest httpServletRequest = castServletRequest(request);
        if (httpServletRequest == null) {
            logger.warn("Null value for incoming HttpServletRequest. Beginning NoOpSegment.");
            return recorder.beginNoOpSegment();
        }

        Optional<TraceHeader> incomingHeader = getTraceHeader(httpServletRequest);
        SamplingStrategy samplingStrategy = recorder.getSamplingStrategy();

        if (logger.isDebugEnabled() && incomingHeader.isPresent()) {
            logger.debug("Incoming trace header received: " + incomingHeader.get().toString());
        }

        SamplingResponse samplingResponse = fromSamplingStrategy(httpServletRequest);

        SampleDecision sampleDecision = incomingHeader.isPresent()
                                        ? incomingHeader.get().getSampled() : getSampleDecision(samplingResponse);
        if (SampleDecision.REQUESTED.equals(sampleDecision) || SampleDecision.UNKNOWN.equals(sampleDecision)) {
            sampleDecision = getSampleDecision(samplingResponse);
        }

        TraceID traceId = null;
        String parentId = null;
        if (incomingHeader.isPresent()) {
            TraceHeader header = incomingHeader.get();
            traceId = header.getRootTraceId();
            parentId = header.getParentId();
        }

        final Segment created;
        if (SampleDecision.SAMPLED.equals(sampleDecision)) {
            String segmentName = getSegmentName(httpServletRequest);
            created = traceId != null
                      ? recorder.beginSegment(segmentName, traceId, parentId)
                      : recorder.beginSegment(segmentName);
            if (samplingResponse.getRuleName().isPresent()) {
                logger.debug("Sampling strategy decided to use rule named: " + samplingResponse.getRuleName().get() + ".");
                created.setRuleName(samplingResponse.getRuleName().get());
            }
        } else { //NOT_SAMPLED
            String segmentName = getSegmentName(httpServletRequest);
            if (samplingStrategy.isForcedSamplingSupported()) {
                created = traceId != null
                          ? recorder.beginSegment(segmentName, traceId, parentId)
                          : recorder.beginSegment(segmentName);
                created.setSampled(false);
            } else {
                logger.debug("Creating Dummy Segment");
                created = traceId != null ? recorder.beginNoOpSegment(traceId) : recorder.beginNoOpSegment();
            }
        }

        Map<String, Object> requestAttributes = new HashMap<String, Object>();
        requestAttributes.put("url", httpServletRequest.getRequestURL().toString());
        requestAttributes.put("method", httpServletRequest.getMethod());

        Optional<String> userAgent = getUserAgent(httpServletRequest);
        if (userAgent.isPresent()) {
            requestAttributes.put("user_agent", userAgent.get());
        }

        Optional<String> xForwardedFor = getXForwardedFor(httpServletRequest);
        if (xForwardedFor.isPresent()) {
            requestAttributes.put("client_ip", xForwardedFor.get());
            requestAttributes.put("x_forwarded_for", true);
        } else {
            Optional<String> clientIp = getClientIp(httpServletRequest);
            if (clientIp.isPresent()) {
                requestAttributes.put("client_ip", clientIp.get());
            }
        }

        created.putHttp("request", requestAttributes);

        HttpServletResponse httpServletResponse = castServletResponse(response);
        if (httpServletResponse == null) {
            return created;
        }

        final TraceHeader responseHeader;
        if (incomingHeader.isPresent()) {
            // create a new header, and use the incoming header so we know what to do in regards to sending back the sampling
            // decision.
            responseHeader = new TraceHeader(created.getTraceId());
            if (SampleDecision.REQUESTED == incomingHeader.get().getSampled()) {
                responseHeader.setSampled(created.isSampled() ? SampleDecision.SAMPLED : SampleDecision.NOT_SAMPLED);
            }
        } else {
            // Create a new header, we're the tracing root. We wont return the sampling decision.
            responseHeader = new TraceHeader(created.getTraceId());
        }
        httpServletResponse.addHeader(TraceHeader.HEADER_KEY, responseHeader.toString());

        return created;
    }