public void addTextHeader()

in apm-agent-core/src/main/java/co/elastic/apm/agent/impl/transaction/TraceState.java [83:155]
58 lines of code
16 McCabe index (conditional complexity)

    public void addTextHeader(String headerValue) {
        cachedResultHeader = null;
        int vendorStart = headerValue.indexOf(VENDOR_PREFIX);

        if (vendorStart < 0) {
            // no ES entry
            tracestate.add(headerValue);
            return;
        }

        int vendorEnd = headerValue.indexOf(VENDOR_SEPARATOR, vendorStart);
        if (vendorEnd < 0) {
            vendorEnd = headerValue.length();
        }

        int sampleRateStart = headerValue.indexOf(SAMPLE_RATE_PREFIX, vendorStart);
        if (sampleRateStart < 0) {
            // no sample rate, rewrite
            log.warn("invalid header, no sample rate {}", headerValue);
            headerValue = rewriteRemoveInvalidHeader(headerValue, vendorStart, vendorEnd);
            if (headerValue.length() > 0) {
                tracestate.add(headerValue);
            }
            return;
        }

        int valueStart = sampleRateStart + 2;
        int valueEnd = valueStart;
        if (valueEnd < headerValue.length()) {
            char c = headerValue.charAt(valueEnd);
            while (valueEnd < headerValue.length() && c != VENDOR_SEPARATOR && c != ENTRY_SEPARATOR) {
                c = headerValue.charAt(valueEnd++);
            }
            if (valueEnd < headerValue.length()) {
                // end due to separator char that needs to be trimmed
                valueEnd--;
            }
        }

        String headerValueString = headerValue.substring(valueStart, valueEnd);
        double value = Double.NaN;
        try {
            value = Double.parseDouble(headerValueString);
        } catch (NumberFormatException e) {
            // silently ignored
        }

        if (Double.isNaN(value) || value < 0 || value > 1) {
            log.warn("invalid sample rate header {}", headerValueString);
            headerValue = rewriteRemoveInvalidHeader(headerValue, vendorStart, vendorEnd);
        } else {
            if (!Double.isNaN(sampleRate)) {
                log.warn("sample rate already set to {}, trying to set it to {} through header will be ignored", sampleRate, value);
                headerValue = rewriteRemoveInvalidHeader(headerValue, vendorStart, vendorEnd);
            } else {
                // ensure proper rounding of sample rate to minimize storage
                // even if configuration should not allow this, any upstream value might require rounding
                double rounded = DOUBLE_CONVERTER.round(value);
                if (rounded != value) {
                    // value needs to be re-written due to rounding
                    headerValue = rewriteRoundedHeader(headerValue, valueStart, valueEnd, rounded);
                    sampleRate = rounded;
                } else {
                    sampleRate = value;
                }
            }
        }

        if (!headerValue.isEmpty()) {
            tracestate.add(headerValue);
        }

    }