Disable capture of entry values (#8369)

jpbempel · web-flow · commit e037162705b2 · 2025-02-12T09:41:12.000+01:00
Due to overhead induced by capturing entry values because we need to
freeze them (serialize as Json) immediately before even know if we are
 sampling it or not, compared to the usefulness of having those values
we only capture at exit by default.
diff --git a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/LogProbe.java b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/LogProbe.java
@@ -444,8 +444,8 @@ public Sampling getSampling() {
   @Override
   public InstrumentationResult.Status instrument(
       MethodInfo methodInfo, List<DiagnosticMessage> diagnostics, List<ProbeId> probeIds) {
-    // if evaluation is at exit and with condition, skip collecting data at entry
-    boolean captureEntry = !(getEvaluateAt() == MethodLocation.EXIT && hasCondition());
+    // only capture entry values if explicitly not at Exit. By default, we are using evaluateAt=EXIT
+    boolean captureEntry = getEvaluateAt() != MethodLocation.EXIT;
     return new CapturedContextInstrumentor(
             this,
             methodInfo,
diff --git a/dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/CapturedSnapshotTest.java b/dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/CapturedSnapshotTest.java
@@ -155,7 +155,8 @@ public void methodProbeAtExit() throws IOException, URISyntaxException {
     int result = Reflect.onClass(testClass).call("main", "1").get();
     assertEquals(3, result);
     Snapshot snapshot = assertOneSnapshot(listener);
-    assertCaptureArgs(snapshot.getCaptures().getEntry(), "arg", "java.lang.String", "1");
+    // no entry values capture
+    assertEquals(CapturedContext.EMPTY_CAPTURING_CONTEXT, snapshot.getCaptures().getEntry());
     assertCaptureArgs(snapshot.getCaptures().getReturn(), "arg", "java.lang.String", "1");
     assertTrue(snapshot.getDuration() > 0);
     assertTrue(snapshot.getStack().size() > 0);
