chaos: restore Maven jar fallback, drop vthread-context-cascade from profiler-only run

Author: jbachorik

utils/run-chaos-harness.sh

@@ -76,12 +76,25 @@ fi
 echo "Using: $(java -version 2>&1 | head -1)"
 
 # --- ddprof jar --------------------------------------------------------------
+# Prefer a local build artifact. If absent and CURRENT_VERSION is set (CI
+# passes it in from the get-versions job), fall back to the Maven snapshot.
 DDPROF_JAR=$(ls "${ROOT}/ddprof-lib/build/libs/ddprof-"*.jar 2>/dev/null | head -1)
 if [ -z "${DDPROF_JAR}" ] || [ ! -f "${DDPROF_JAR}" ]; then
-  echo "FAIL:no local ddprof jar found — build one first: ./gradlew :ddprof-lib:jar" >&2
-  exit 1
+  if [ -z "${CURRENT_VERSION:-}" ]; then
+    echo "FAIL:no local ddprof jar found and CURRENT_VERSION is empty — build one first: ./gradlew :ddprof-lib:jar" >&2
+    exit 1
+  fi
+  echo "Local ddprof jar not found — downloading ${CURRENT_VERSION} from Maven snapshots"
+  ( cd /tmp && mvn org.apache.maven.plugins:maven-dependency-plugin:2.1:get \
+      -DrepoUrl=https://central.sonatype.com/repository/maven-snapshots/ \
+      -Dartifact=com.datadoghq:ddprof:"${CURRENT_VERSION}" )
+  DDPROF_JAR="/root/.m2/repository/com/datadoghq/ddprof/${CURRENT_VERSION}/ddprof-${CURRENT_VERSION}.jar"
+  if [ ! -f "${DDPROF_JAR}" ]; then
+    echo "FAIL:ddprof jar unavailable (Maven snapshot download failed)" >&2
+    exit 1
+  fi
 fi
-echo "Using local ddprof jar: ${DDPROF_JAR}"
+echo "Using ddprof jar: ${DDPROF_JAR}"
 
 # --- dd-java-agent ------------------------------------------------------------
 DD_AGENT_JAR="${WORK_DIR}/dd-java-agent.jar"
@@ -117,8 +130,10 @@ fi
 case $CONFIG in
   profiler)
     ENABLEMENT="-Ddd.profiling.enabled=true -Ddd.trace.enabled=false"
-    # @Trace is a no-op without the tracer, so trace-context is excluded here.
-    DEFAULT_ANTAGONISTS="thread-churn,alloc-storm,vthread-churn,classloader-churn,vthread-context-cascade,bounded-pool,context-hop,consumer-group,hidden-class-churn,direct-memory,weakref-wave,dump-storm"
+    # @Trace is a no-op without the tracer, so trace-context and
+    # vthread-context-cascade (which is driven entirely by @Trace-annotated
+    # methods) are excluded here.
+    DEFAULT_ANTAGONISTS="thread-churn,alloc-storm,vthread-churn,classloader-churn,bounded-pool,context-hop,consumer-group,hidden-class-churn,direct-memory,weakref-wave,dump-storm"
     ;;
   profiler+tracer)
     ENABLEMENT="-Ddd.profiling.enabled=true -Ddd.trace.enabled=true"