add config for local var hoisting

jpbempel · jpbempel · commit f86bd77ed804 · 2024-12-12T20:49:43.000+01:00
enable only hoisting for java language
diff --git a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/instrumentation/CapturedContextInstrumentor.java b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/instrumentation/CapturedContextInstrumentor.java
@@ -396,7 +396,11 @@ private void instrumentMethodEnter() {
     if (methodNode.tryCatchBlocks.size() > 0) {
       throwableListVar = declareThrowableList(insnList);
     }
-    unscopedLocalVars = initAndHoistLocalVars(insnList);
+    unscopedLocalVars = Collections.emptyList();
+    if (Config.get().isDebuggerHoistLocalVarsEnabled() && language == JvmLanguage.JAVA) {
+      // for now, only hoist local vars for Java
+      unscopedLocalVars = initAndHoistLocalVars(insnList);
+    }
     insnList.add(contextInitLabel);
     if (definition instanceof SpanDecorationProbe
         && definition.getEvaluateAt() == MethodLocation.EXIT) {
diff --git a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/instrumentation/Instrumentor.java b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/instrumentation/Instrumentor.java
@@ -46,6 +46,7 @@ public abstract class Instrumentor {
   protected int localVarBaseOffset;
   protected int argOffset;
   protected final LocalVariableNode[] localVarsBySlotArray;
+  protected final JvmLanguage language;
   protected LabelNode returnHandlerLabel;
   protected final List<CapturedContextInstrumentor.FinallyBlock> finallyBlocks = new ArrayList<>();
 
@@ -69,6 +70,7 @@ public Instrumentor(
       argOffset += t.getSize();
     }
     localVarsBySlotArray = extractLocalVariables(argTypes);
+    this.language = JvmLanguage.of(classNode);
   }
 
   public abstract InstrumentationResult.Status instrument();
@@ -294,4 +296,31 @@ public FinallyBlock(LabelNode startLabel, LabelNode endLabel, LabelNode handlerL
       this.handlerLabel = handlerLabel;
     }
   }
+
+  protected enum JvmLanguage {
+    JAVA,
+    KOTLIN,
+    SCALA,
+    GROOVY,
+    UNKNOWN;
+
+    public static JvmLanguage of(ClassNode classNode) {
+      if (classNode.sourceFile == null) {
+        return UNKNOWN;
+      }
+      if (classNode.sourceFile.endsWith(".java")) {
+        return JAVA;
+      }
+      if (classNode.sourceFile.endsWith(".kt")) {
+        return KOTLIN;
+      }
+      if (classNode.sourceFile.endsWith(".scala")) {
+        return SCALA;
+      }
+      if (classNode.sourceFile.endsWith(".groovy")) {
+        return GROOVY;
+      }
+      return UNKNOWN;
+    }
+  }
 }
diff --git a/dd-trace-api/src/main/java/datadog/trace/api/ConfigDefaults.java b/dd-trace-api/src/main/java/datadog/trace/api/ConfigDefaults.java
@@ -179,6 +179,7 @@ public final class ConfigDefaults {
   static final boolean DEFAULT_DEBUGGER_VERIFY_BYTECODE = true;
   static final boolean DEFAULT_DEBUGGER_INSTRUMENT_THE_WORLD = false;
   static final int DEFAULT_DEBUGGER_CAPTURE_TIMEOUT = 100; // milliseconds
+  static final boolean DEFAULT_DEBUGGER_HOIST_LOCALVARS_ENABLED = true;
   static final boolean DEFAULT_DEBUGGER_SYMBOL_ENABLED = true;
   static final boolean DEFAULT_DEBUGGER_SYMBOL_FORCE_UPLOAD = false;
   static final int DEFAULT_DEBUGGER_SYMBOL_FLUSH_THRESHOLD = 100; // nb of classes
diff --git a/dd-trace-api/src/main/java/datadog/trace/api/config/DebuggerConfig.java b/dd-trace-api/src/main/java/datadog/trace/api/config/DebuggerConfig.java
@@ -28,6 +28,8 @@ public final class DebuggerConfig {
   public static final String DEBUGGER_REDACTION_EXCLUDED_IDENTIFIERS =
       "dynamic.instrumentation.redaction.excluded.identifiers";
   public static final String DEBUGGER_REDACTED_TYPES = "dynamic.instrumentation.redacted.types";
+  public static final String DEBUGGER_HOIST_LOCALVARS_ENABLED =
+      "dynamic.instrumentation.hoist.localvars.enabled";
   public static final String DEBUGGER_SYMBOL_ENABLED = "symbol.database.upload.enabled";
   public static final String DEBUGGER_SYMBOL_FORCE_UPLOAD = "internal.force.symbol.database.upload";
   public static final String DEBUGGER_SYMBOL_INCLUDES = "symbol.database.includes";
diff --git a/internal-api/src/main/java/datadog/trace/api/Config.java b/internal-api/src/main/java/datadog/trace/api/Config.java
@@ -394,6 +394,7 @@ public static String getHostName() {
   private final String debuggerRedactedIdentifiers;
   private final Set<String> debuggerRedactionExcludedIdentifiers;
   private final String debuggerRedactedTypes;
+  private final boolean debuggerHoistLocalVarsEnabled;
   private final boolean debuggerSymbolEnabled;
   private final boolean debuggerSymbolForceUpload;
   private final String debuggerSymbolIncludes;
@@ -1526,6 +1527,9 @@ PROFILING_DATADOG_PROFILER_ENABLED, isDatadogProfilerSafeInCurrentEnvironment())
     debuggerRedactionExcludedIdentifiers =
         tryMakeImmutableSet(configProvider.getList(DEBUGGER_REDACTION_EXCLUDED_IDENTIFIERS));
     debuggerRedactedTypes = configProvider.getString(DEBUGGER_REDACTED_TYPES, null);
+    debuggerHoistLocalVarsEnabled =
+        configProvider.getBoolean(
+            DEBUGGER_HOIST_LOCALVARS_ENABLED, DEFAULT_DEBUGGER_HOIST_LOCALVARS_ENABLED);
     debuggerSymbolEnabled =
         configProvider.getBoolean(DEBUGGER_SYMBOL_ENABLED, DEFAULT_DEBUGGER_SYMBOL_ENABLED);
     debuggerSymbolForceUpload =
@@ -3042,6 +3046,10 @@ public String getDebuggerRedactedTypes() {
     return debuggerRedactedTypes;
   }
 
+  public boolean isDebuggerHoistLocalVarsEnabled() {
+    return debuggerHoistLocalVarsEnabled;
+  }
+
   public boolean isAwsPropagationEnabled() {
     return awsPropagationEnabled;
   }
