Move base and peer service adder before span is published (#9408)

* Move base and peer service adder before span is published
* Change method signature to fix ugly groovy issues
* feat(tracer): Introduce eager span tag processors

---------

Co-authored-by: Bruce Bujon <bruce.bujon@datadoghq.com>

Author: amarziali

dd-trace-core/src/main/java/datadog/trace/core/CoreSpan.java

@@ -68,6 +68,13 @@ public interface CoreSpan<T extends CoreSpan<T>> {
 
   CharSequence getType();
 
+  /**
+   * Runs early {@link datadog.trace.core.tagprocessor.TagsPostProcessor} like base service and peer
+   * service computation. Such tags are needed before span serialization so they can’t be processed
+   * lazily as part of the {@link #processTagsAndBaggage(MetadataConsumer)} API.
+   */
+  void processServiceTags();
+
   void processTagsAndBaggage(MetadataConsumer consumer);
 
   T setSamplingPriority(int samplingPriority, int samplingMechanism);

dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java

@@ -1109,6 +1109,12 @@ void write(final List<DDSpan> trace) {
     if (writtenTrace.isEmpty()) {
       return;
     }
+
+    // run early tag postprocessors before publishing to the metrics writer since peer / base
+    // service are needed
+    for (DDSpan span : writtenTrace) {
+      span.processServiceTags();
+    }
     boolean forceKeep = metricsAggregator.publish(writtenTrace);
 
     TraceCollector traceCollector = writtenTrace.get(0).context().getTraceCollector();

dd-trace-core/src/main/java/datadog/trace/core/DDSpan.java

@@ -694,7 +694,7 @@ public String getSpanType() {
 
   @Override
   public TagMap getTags() {
-    // This is an imutable copy of the tags
+    // This is an immutable copy of the tags
     return context.getTags();
   }
 
@@ -703,6 +703,11 @@ public CharSequence getType() {
     return context.getSpanType();
   }
 
+  @Override
+  public void processServiceTags() {
+    context.earlyProcessTags(links);
+  }
+
   @Override
   public void processTagsAndBaggage(final MetadataConsumer consumer) {
     context.processTagsAndBaggage(consumer, longRunningVersion, links);

dd-trace-core/src/main/java/datadog/trace/core/DDSpanContext.java

@@ -921,11 +921,17 @@ public <T> void setMetaStruct(final String field, final T value) {
     }
   }
 
+  public void earlyProcessTags(List<AgentSpanLink> links) {
+    synchronized (unsafeTags) {
+      TagsPostProcessorFactory.eagerProcessor().processTags(unsafeTags, this, links);
+    }
+  }
+
   public void processTagsAndBaggage(
       final MetadataConsumer consumer, int longRunningVersion, List<AgentSpanLink> links) {
     synchronized (unsafeTags) {
       // Tags
-      TagsPostProcessorFactory.instance().processTags(unsafeTags, this, links);
+      TagsPostProcessorFactory.lazyProcessor().processTags(unsafeTags, this, links);
 
       String linksTag = DDSpanLink.toTag(links);
       if (linksTag != null) {

dd-trace-core/src/main/java/datadog/trace/core/tagprocessor/TagsPostProcessorFactory.java

@@ -9,12 +9,21 @@ public final class TagsPostProcessorFactory {
   private static boolean addRemoteHostname = true;
 
   private static class Lazy {
-    private static TagsPostProcessor create() {
-      final List<TagsPostProcessor> processors = new ArrayList<>(7);
+    private static TagsPostProcessor eagerProcessor = createEagerChain();
+    private static TagsPostProcessor lazyProcessor = createLazyChain();
+
+    private static TagsPostProcessor createEagerChain() {
+      final List<TagsPostProcessor> processors = new ArrayList<>(2);
       processors.add(new PeerServiceCalculator());
       if (addBaseService) {
         processors.add(new BaseServiceAdder(Config.get().getServiceName()));
       }
+      return new PostProcessorChain(processors.toArray(new TagsPostProcessor[0]));
+    }
+
+    private static TagsPostProcessor createLazyChain() {
+      final List<TagsPostProcessor> processors = new ArrayList<>(7);
+
       processors.add(new QueryObfuscator(Config.get().getObfuscationQueryRegexp()));
       if (addRemoteHostname) {
         processors.add(new RemoteHostnameAdder(Config.get().getHostNameSupplier()));
@@ -36,12 +45,14 @@ private static TagsPostProcessor create() {
       return new PostProcessorChain(
           processors.toArray(processors.toArray(new TagsPostProcessor[0])));
     }
+  }
 
-    private static TagsPostProcessor instance = create();
+  public static TagsPostProcessor eagerProcessor() {
+    return Lazy.eagerProcessor;
   }
 
-  public static TagsPostProcessor instance() {
-    return Lazy.instance;
+  public static TagsPostProcessor lazyProcessor() {
+    return Lazy.lazyProcessor;
   }
 
   /**
@@ -51,7 +62,7 @@ public static TagsPostProcessor instance() {
    */
   public static void withAddBaseService(boolean enabled) {
     addBaseService = enabled;
-    Lazy.instance = Lazy.create();
+    Lazy.eagerProcessor = Lazy.createEagerChain();
   }
 
   /**
@@ -61,7 +72,7 @@ public static void withAddBaseService(boolean enabled) {
    */
   public static void withAddRemoteHostname(boolean enabled) {
     addRemoteHostname = enabled;
-    Lazy.instance = Lazy.create();
+    Lazy.lazyProcessor = Lazy.createLazyChain();
   }
 
   /** Used for testing purposes. It reset the singleton and restore default options */

dd-trace-core/src/test/groovy/datadog/trace/common/metrics/SimpleSpan.groovy

@@ -206,6 +206,9 @@ class SimpleSpan implements CoreSpan<SimpleSpan> {
     return type
   }
 
+  @Override
+  void processServiceTags() {}
+
   @Override
   void processTagsAndBaggage(MetadataConsumer consumer) {}
 

dd-trace-core/src/test/groovy/datadog/trace/common/writer/TraceGenerator.groovy

@@ -333,6 +333,9 @@ class TraceGenerator {
       return this.type
     }
 
+    @Override
+    void processServiceTags() {}
+
     @Override
     void processTagsAndBaggage(MetadataConsumer consumer) {
       consumer.accept(metadata)

dd-trace-core/src/traceAgentTest/groovy/TraceGenerator.groovy

@@ -309,6 +309,9 @@ class TraceGenerator {
       return type
     }
 
+    @Override
+    void processServiceTags() {}
+
     @Override
     void processTagsAndBaggage(MetadataConsumer consumer) {
       consumer.accept(metadata)