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The LightStep OpenTracing Tracer implementation for Java

There is a newer version: 0.32.0

package com.lightstep.tracer.shared;

import io.opentracing.propagation.TextMapInject;
import io.opentracing.propagation.TextMapExtract;
import java.util.Map;

public class B3Propagator implements Propagator {

    private static final String TRACE_ID_NAME = "X-B3-TraceId";
    private static final String SPAN_ID_NAME = "X-B3-SpanId";
    private static final String SAMPLED_NAME = "X-B3-Sampled";

    @Override
    public  void inject(SpanContext spanContext, C carrier) {
        if (!(carrier instanceof TextMapInject)) {
            return;
        }

        TextMapInject textCarrier = (TextMapInject) carrier;
        long traceId = spanContext.getTraceId();
        long spanId = spanContext.getSpanId();

        textCarrier.put(TRACE_ID_NAME, Util.toHexString(traceId));
        textCarrier.put(SPAN_ID_NAME, Util.toHexString(spanId));
        textCarrier.put(SAMPLED_NAME, "true");
    }

    @Override
    public  SpanContext extract(C carrier) {
        if (!(carrier instanceof TextMapExtract)) {
            return null;
        }

        Long traceId = null;
        Long spanId = null;

        for (Map.Entry entry : (TextMapExtract)carrier) {
            if (entry.getKey().equalsIgnoreCase(TRACE_ID_NAME)) {
                traceId = Util.fromHexString(entry.getValue());
            } else if (entry.getKey().equalsIgnoreCase(SPAN_ID_NAME)) {
                spanId = Util.fromHexString(entry.getValue());
            }
        }

        if (null != traceId && null != spanId) {
            return new SpanContext(traceId, spanId);
        }

        return null;
    }
}