Fix potential corner-case where TagContext.getTags() may return an immutable EMPTY TagMap

Author: mcculls

dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/decorator/HttpServerDecorator.java

@@ -12,7 +12,6 @@
 import datadog.context.propagation.Propagators;
 import datadog.trace.api.Config;
 import datadog.trace.api.DDTags;
-import datadog.trace.api.TagMap;
 import datadog.trace.api.function.TriConsumer;
 import datadog.trace.api.function.TriFunction;
 import datadog.trace.api.gateway.BlockResponseFunction;
@@ -663,18 +662,17 @@ private static void setBaggageTags(TagContext tagContext, Map<String, String> ba
     if (baggageTagKeys.isEmpty()) {
       return;
     }
-    TagMap tags = tagContext.getTags();
     for (String key : baggageTagKeys) {
       if ("*".equals(key)) {
         // If the key is "*", we add all baggage items
         for (Map.Entry<String, String> entry : baggage.entrySet()) {
-          tags.putIfAbsent("baggage." + entry.getKey(), entry.getValue());
+          tagContext.putTagIfAbsent("baggage." + entry.getKey(), entry.getValue());
         }
         break;
       }
       String value = baggage.get(key);
       if (value != null) {
-        tags.putIfAbsent("baggage." + key, value);
+        tagContext.putTagIfAbsent("baggage." + key, value);
       }
     }
   }

dd-trace-core/src/test/groovy/datadog/trace/core/CoreTracerTest.groovy

@@ -38,7 +38,6 @@ import static datadog.trace.api.config.TracerConfig.HEADER_TAGS
 import static datadog.trace.api.config.TracerConfig.PRIORITY_SAMPLING
 import static datadog.trace.api.config.TracerConfig.SERVICE_MAPPING
 import static datadog.trace.api.config.TracerConfig.SPAN_TAGS
-import static datadog.trace.api.config.TracerConfig.TRACE_BAGGAGE_TAG_KEYS
 import static datadog.trace.api.config.TracerConfig.WRITER_TYPE
 
 @Timeout(10)
@@ -640,33 +639,6 @@ class CoreTracerTest extends DDCoreSpecification {
     "service" | "env"  | "service"     | "env_1"
     "service" | "env"  | "service_2"   | "env_2"
   }
-
-  def "test mapBaggageTags default"() {
-    when:
-    def tags = CoreTracer.mapBaggageTags(["user.id": "doggo", "account.id": "test", "session.id":"1234", "region":"us-east-1"])
-    then:
-    tags == ["baggage.user.id": "doggo", "baggage.account.id": "test", "baggage.session.id": "1234"]
-  }
-
-  def "test mapBaggageTags with different configurations"() {
-    setup:
-    injectSysConfig(TRACE_BAGGAGE_TAG_KEYS, baggageTagKeysConfig)
-
-    when:
-    def tags = CoreTracer.mapBaggageTags(["user.id": "doggo", "foo": "bar", "language":"en"])
-
-    then:
-    tags == expectedTags
-
-    where:
-    baggageTagKeysConfig | expectedTags
-    "*"                  | ["baggage.user.id": "doggo", "baggage.foo": "bar", "baggage.language": "en"]
-    " "                  | [:]
-    "system.id"          | [:]
-    "user.id"            | ["baggage.user.id": "doggo"]
-    "foo"                | ["baggage.foo": "bar"]
-    "user.id,foo"        | ["baggage.user.id": "doggo", "baggage.foo": "bar"]
-  }
 }
 
 class WriterWithExplicitFlush implements datadog.trace.common.writer.Writer {

internal-api/src/main/java/datadog/trace/bootstrap/instrumentation/api/TagContext.java

@@ -175,6 +175,15 @@ public void putTag(final String key, final String value) {
     this.tags.set(key, value);
   }
 
+  public void putTagIfAbsent(final String key, final String value) {
+    if (this.tags == null) {
+      this.tags = TagMap.create(4);
+    }
+    if (!this.tags.containsKey(key)) {
+      this.tags.set(key, value);
+    }
+  }
+
   @Override
   public final int getSamplingPriority() {
     return samplingPriority;