feat(core): Add multiple context extraction

Extract multiple propagated context according the new W3C trace context initiative.
Add a config to limit to the first valid one.

dd-java-agent/instrumentation/opentelemetry/opentelemetry-0.3/src/test/groovy/OpenTelemetryTest.groovy

@@ -3,6 +3,8 @@ import datadog.trace.api.DDTags
 import datadog.trace.api.DDTraceId
 import datadog.trace.api.interceptor.MutableSpan
 import datadog.trace.core.propagation.PropagationTags
+
+import static datadog.trace.api.TracePropagationStyle.NONE
 import static datadog.trace.api.sampling.PrioritySampling.*
 import static datadog.trace.api.sampling.SamplingMechanism.*
 import datadog.trace.context.TraceScope
@@ -135,11 +137,11 @@ class OpenTelemetryTest extends AgentTestRunner {
     setup:
     def builder = tracer.spanBuilder("some name")
     if (parentId) {
-      def ctx = new ExtractedContext(DDTraceId.ONE, parentId, SAMPLER_DROP, null, PropagationTags.factory().empty())
+      def ctx = new ExtractedContext(DDTraceId.ONE, parentId, SAMPLER_DROP, null, PropagationTags.factory().empty(), NONE)
       builder.setParent(tracer.converter.toSpanContext(ctx))
     }
     if (linkId) {
-      def ctx = new ExtractedContext(DDTraceId.ONE, linkId, SAMPLER_DROP, null, PropagationTags.factory().empty())
+      def ctx = new ExtractedContext(DDTraceId.ONE, linkId, SAMPLER_DROP, null, PropagationTags.factory().empty(), NONE)
       builder.addLink(tracer.converter.toSpanContext(ctx))
     }
     def result = builder.startSpan()

dd-java-agent/instrumentation/opentracing/api-0.31/src/test/groovy/OpenTracing31Test.groovy

@@ -10,6 +10,7 @@ import datadog.trace.instrumentation.opentracing31.OTTracer
 import datadog.trace.instrumentation.opentracing31.TypeConverter
 import spock.lang.Shared
 
+import static datadog.trace.api.TracePropagationStyle.NONE
 import static datadog.trace.api.sampling.PrioritySampling.*
 import static datadog.trace.api.sampling.SamplingMechanism.*
 import datadog.trace.context.TraceScope
@@ -45,7 +46,7 @@ class OpenTracing31Test extends AgentTestRunner {
         .withTag("boolean", true)
     }
     if (addReference) {
-      def ctx = new ExtractedContext(DDTraceId.ONE, 2, SAMPLER_DROP, null, PropagationTags.factory().empty())
+      def ctx = new ExtractedContext(DDTraceId.ONE, 2, SAMPLER_DROP, null, PropagationTags.factory().empty(), NONE)
       builder.addReference(addReference, tracer.tracer.converter.toSpanContext(ctx))
     }
     def result = builder.start()

dd-java-agent/instrumentation/opentracing/api-0.32/src/test/groovy/OpenTracing32Test.groovy

@@ -23,6 +23,7 @@ import spock.lang.Shared
 import spock.lang.Subject
 
 import static datadog.trace.agent.test.utils.TraceUtils.runUnderTrace
+import static datadog.trace.api.TracePropagationStyle.NONE
 import static datadog.trace.api.sampling.PrioritySampling.SAMPLER_DROP
 import static datadog.trace.api.sampling.PrioritySampling.SAMPLER_KEEP
 import static datadog.trace.api.sampling.PrioritySampling.UNSET
@@ -50,7 +51,7 @@ class OpenTracing32Test extends AgentTestRunner {
         .withTag("boolean", true)
     }
     if (addReference) {
-      def ctx = new ExtractedContext(DDTraceId.ONE, 2, SAMPLER_DROP, null, PropagationTags.factory().empty())
+      def ctx = new ExtractedContext(DDTraceId.ONE, 2, SAMPLER_DROP, null, PropagationTags.factory().empty(), NONE)
       builder.addReference(addReference, tracer.tracer.converter.toSpanContext(ctx))
     }
     def result = builder.start()

dd-trace-api/src/main/java/datadog/trace/api/ConfigDefaults.java

@@ -71,6 +71,8 @@ public final class ConfigDefaults {
 
   static final int DEFAULT_CLOCK_SYNC_PERIOD = 30; // seconds
 
+  static final boolean DEFAULT_TRACE_PROPAGATION_EXTRACT_FIRST = false;
+
   static final boolean DEFAULT_JMX_FETCH_MULTIPLE_RUNTIME_SERVICES_ENABLED = false;
   static final int DEFAULT_JMX_FETCH_MULTIPLE_RUNTIME_SERVICES_LIMIT = 10;
 

dd-trace-api/src/main/java/datadog/trace/api/config/TracerConfig.java

@@ -84,6 +84,7 @@ public final class TracerConfig {
   public static final String TRACE_PROPAGATION_STYLE = "trace.propagation.style";
   public static final String TRACE_PROPAGATION_STYLE_EXTRACT = "trace.propagation.style.extract";
   public static final String TRACE_PROPAGATION_STYLE_INJECT = "trace.propagation.style.inject";
+  public static final String TRACE_PROPAGATION_EXTRACT_FIRST = "trace.propagation.extract.first";
 
   public static final String ENABLE_TRACE_AGENT_V05 = "trace.agent.v0.5.enabled";
 

dd-trace-core/src/main/java/datadog/trace/core/propagation/B3HttpCodec.java

@@ -1,12 +1,15 @@
 package datadog.trace.core.propagation;
 
+import static datadog.trace.api.TracePropagationStyle.B3MULTI;
+import static datadog.trace.api.TracePropagationStyle.B3SINGLE;
 import static datadog.trace.core.propagation.HttpCodec.firstHeaderValue;
 
 import datadog.trace.api.Config;
 import datadog.trace.api.DD128bTraceId;
 import datadog.trace.api.DDSpanId;
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.TraceConfig;
+import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.api.sampling.PrioritySampling;
 import datadog.trace.bootstrap.instrumentation.api.AgentPropagation;
 import datadog.trace.core.DDSpanContext;
@@ -161,7 +164,7 @@ static HttpCodec.Extractor newExtractor(
     final List<HttpCodec.Extractor> extractors = new ArrayList<>(2);
     extractors.add(newSingleExtractor(config, traceConfigSupplier));
     extractors.add(newMultiExtractor(config, traceConfigSupplier));
-    return new HttpCodec.CompoundExtractor(extractors);
+    return new HttpCodec.CompoundExtractor(extractors, config.isTracePropagationExtractFirst());
   }
 
   public static HttpCodec.Extractor newMultiExtractor(
@@ -212,6 +215,11 @@ private B3MultiContextInterpreter(Config config) {
       super(config);
     }
 
+    @Override
+    public TracePropagationStyle style() {
+      return B3MULTI;
+    }
+
     @Override
     public boolean accept(final String key, final String value) {
       if (null == key || key.isEmpty() || null == value || value.isEmpty()) {
@@ -267,6 +275,11 @@ public B3SingleContextInterpreter(Config config) {
       super(config);
     }
 
+    @Override
+    public TracePropagationStyle style() {
+      return B3SINGLE;
+    }
+
     @Override
     public boolean accept(String key, String value) {
       try {

dd-trace-core/src/main/java/datadog/trace/core/propagation/ContextInterpreter.java

@@ -21,6 +21,7 @@
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.Functions;
 import datadog.trace.api.TraceConfig;
+import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.api.cache.DDCache;
 import datadog.trace.api.cache.DDCaches;
 import datadog.trace.api.sampling.PrioritySampling;
@@ -58,7 +59,7 @@ public abstract class ContextInterpreter implements AgentPropagation.KeyClassifi
   protected static final boolean LOG_EXTRACT_HEADER_NAMES = Config.get().isLogExtractHeaderNames();
   private static final DDCache<String, String> CACHE = DDCaches.newFixedSizeCache(64);
 
-  protected String toLowerCase(String key) {
+  protected static String toLowerCase(String key) {
     return CACHE.computeIfAbsent(key, Functions.LowerCase.INSTANCE);
   }
 
@@ -68,9 +69,12 @@ protected ContextInterpreter(Config config) {
     this.clientIpWithoutAppSec = config.isClientIpEnabled();
   }
 
-  public interface Factory {
-    ContextInterpreter create();
-  }
+  /**
+   * Gets the propagation style handled by the context interpreter.
+   *
+   * @return The propagation style handled.
+   */
+  public abstract TracePropagationStyle style();
 
   protected final boolean handledForwarding(String key, String value) {
     if (value == null || !collectIpHeaders) {
@@ -241,7 +245,8 @@ protected TagContext build() {
                 tags,
                 httpHeaders,
                 propagationTags,
-                traceConfig);
+                traceConfig,
+                style());
         return context;
       } else if (origin != null
           || !tags.isEmpty()
@@ -254,7 +259,8 @@ protected TagContext build() {
             httpHeaders,
             baggage,
             samplingPriorityOrDefault(traceId, samplingPriority),
-            traceConfig);
+            traceConfig,
+            style());
       }
     }
     return null;
@@ -284,4 +290,8 @@ private int samplingPriorityOrDefault(DDTraceId traceId, int samplingPriority) {
         ? defaultSamplingPriority()
         : samplingPriority;
   }
+
+  public interface Factory {
+    ContextInterpreter create();
+  }
 }

dd-trace-core/src/main/java/datadog/trace/core/propagation/DatadogHttpCodec.java

@@ -1,5 +1,6 @@
 package datadog.trace.core.propagation;
 
+import static datadog.trace.api.TracePropagationStyle.DATADOG;
 import static datadog.trace.core.propagation.HttpCodec.firstHeaderValue;
 import static datadog.trace.core.propagation.XRayHttpCodec.XRayContextInterpreter.handleXRayTraceHeader;
 import static datadog.trace.core.propagation.XRayHttpCodec.X_AMZN_TRACE_ID;
@@ -12,6 +13,7 @@
 import datadog.trace.api.DDTags;
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.TraceConfig;
+import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.bootstrap.instrumentation.api.AgentPropagation;
 import datadog.trace.bootstrap.instrumentation.api.TagContext;
 import datadog.trace.core.DDSpanContext;
@@ -109,6 +111,11 @@ private DatadogContextInterpreter(Config config) {
       datadogTagsFactory = PropagationTags.factory(config);
     }
 
+    @Override
+    public TracePropagationStyle style() {
+      return DATADOG;
+    }
+
     @Override
     public boolean accept(String key, String value) {
       if (null == key || key.isEmpty()) {

dd-trace-core/src/main/java/datadog/trace/core/propagation/ExtractedContext.java

@@ -2,6 +2,7 @@
 
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.TraceConfig;
+import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.api.sampling.PrioritySampling;
 import datadog.trace.bootstrap.instrumentation.api.TagContext;
 import java.util.Map;
@@ -20,8 +21,20 @@ public ExtractedContext(
       final long spanId,
       final int samplingPriority,
       final CharSequence origin,
-      final PropagationTags propagationTags) {
-    this(traceId, spanId, samplingPriority, origin, 0, null, null, null, propagationTags, null);
+      final PropagationTags propagationTags,
+      final TracePropagationStyle propagationStyle) {
+    this(
+        traceId,
+        spanId,
+        samplingPriority,
+        origin,
+        0,
+        null,
+        null,
+        null,
+        propagationTags,
+        null,
+        propagationStyle);
   }
 
   public ExtractedContext(
@@ -34,8 +47,9 @@ public ExtractedContext(
       final Map<String, String> tags,
       final HttpHeaders httpHeaders,
       final PropagationTags propagationTags,
-      final TraceConfig traceConfig) {
-    super(origin, tags, httpHeaders, baggage, samplingPriority, traceConfig);
+      final TraceConfig traceConfig,
+      final TracePropagationStyle propagationStyle) {
+    super(origin, tags, httpHeaders, baggage, samplingPriority, traceConfig, propagationStyle);
     this.traceId = traceId;
     this.spanId = spanId;
     this.endToEndStartTime = endToEndStartTime;

dd-trace-core/src/main/java/datadog/trace/core/propagation/HaystackHttpCodec.java

@@ -1,12 +1,14 @@
 package datadog.trace.core.propagation;
 
+import static datadog.trace.api.TracePropagationStyle.HAYSTACK;
 import static datadog.trace.core.propagation.HttpCodec.firstHeaderValue;
 
 import datadog.trace.api.Config;
 import datadog.trace.api.DD64bTraceId;
 import datadog.trace.api.DDSpanId;
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.TraceConfig;
+import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.api.sampling.PrioritySampling;
 import datadog.trace.bootstrap.instrumentation.api.AgentPropagation;
 import datadog.trace.core.DDSpanContext;
@@ -139,6 +141,11 @@ private HaystackContextInterpreter(Config config) {
       super(config);
     }
 
+    @Override
+    public TracePropagationStyle style() {
+      return HAYSTACK;
+    }
+
     @Override
     public boolean accept(String key, String value) {
       if (null == key || key.isEmpty()) {

dd-trace-core/src/main/java/datadog/trace/core/propagation/HttpCodec.java

@@ -1,5 +1,7 @@
 package datadog.trace.core.propagation;
 
+import static datadog.trace.api.TracePropagationStyle.TRACECONTEXT;
+
 import datadog.trace.api.Config;
 import datadog.trace.api.TraceConfig;
 import datadog.trace.api.TracePropagationStyle;
@@ -46,7 +48,17 @@ <C> void inject(
         final DDSpanContext context, final C carrier, final AgentPropagation.Setter<C> setter);
   }
 
+  /** This interface defines propagated context extractor. */
   public interface Extractor {
+    /**
+     * Extracts a propagated context from the given carrier using the provided getter.
+     *
+     * @param carrier The carrier containing the propagated context.
+     * @param getter The getter used to extract data from the carrier.
+     * @param <C> The type of the carrier.
+     * @return {@code null} for failed context extraction, a {@link TagContext} instance for partial
+     *     context extraction or an {@link ExtractedContext} for complete context extraction.
+     */
     <C> TagContext extract(final C carrier, final AgentPropagation.ContextVisitor<C> getter);
   }
 
@@ -136,7 +148,7 @@ public static Extractor createExtractor(
           break;
       }
     }
-    return new CompoundExtractor(extractors);
+    return new CompoundExtractor(extractors, config.isTracePropagationExtractFirst());
   }
 
   public static class CompoundInjector implements Injector {
@@ -159,27 +171,58 @@ public <C> void inject(
 
   public static class CompoundExtractor implements Extractor {
     private final List<Extractor> extractors;
+    private final boolean extractFirst;
 
-    public CompoundExtractor(final List<Extractor> extractors) {
+    public CompoundExtractor(final List<Extractor> extractors, boolean extractFirst) {
       this.extractors = extractors;
+      this.extractFirst = extractFirst;
     }
 
     @Override
     public <C> TagContext extract(
         final C carrier, final AgentPropagation.ContextVisitor<C> getter) {
-      TagContext context = null;
-
-      for (final Extractor extractor : extractors) {
-        context = extractor.extract(carrier, getter);
-        // Use incomplete TagContext only as last resort
-        if (context instanceof ExtractedContext) {
-          log.debug("Extract complete context {}", context);
-          return context;
+      ExtractedContext context = null;
+      TagContext partialContext = null;
+
+      for (final Extractor extractor : this.extractors) {
+        TagContext extracted = extractor.extract(carrier, getter);
+        // Check if context is valid
+        if (extracted instanceof ExtractedContext) {
+          // If no prior valid context, store it as first valid context
+          if (context == null) {
+            context = (ExtractedContext) extracted;
+            // Stop extraction if only extracting first valid context and drop everything else
+            if (this.extractFirst) {
+              break;
+            }
+          }
+          // If another valid context is extracted
+          else {
+            boolean comingFromTraceContext = extracted.getPropagationStyle() == TRACECONTEXT;
+            boolean traceIdMatches = context.getTraceId().equals(extracted.getTraceId());
+            if (comingFromTraceContext && traceIdMatches) {
+              // Propagate newly extracted W3C tracestate to first valid context
+              // TODO
+              //              context.
+            }
+          }
+        }
+        // Check if context is at least partial to keep it as first valid partial context found
+        else if (extracted != null && partialContext == null) {
+          partialContext = extracted;
         }
       }
 
-      log.debug("Extract incomplete context {}", context);
-      return context;
+      if (context != null) {
+        log.debug("Extract complete context {}", context);
+        return context;
+      } else if (partialContext != null) {
+        log.debug("Extract incomplete context {}", partialContext);
+        return partialContext;
+      } else {
+        log.debug("Extract no context");
+        return null;
+      }
     }
   }