Fix perf issue when accessing fields by reflection (#7052)

Instead of relying on exception using `getDeclaredField(String)` we are using `getDeclaredFields()` and scanning the field by name.
DataDog · May 21, 2024 · bd6a986 · bd6a986
1 parent dedce3e
commit bd6a986
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Showing 2 changed files with 37 additions and 6 deletions.
diff --git a/...strap/src/main/java/datadog/trace/bootstrap/debugger/el/ReflectiveFieldValueResolver.java b/...strap/src/main/java/datadog/trace/bootstrap/debugger/el/ReflectiveFieldValueResolver.java
@@ -165,13 +165,15 @@ private static Field safeGetField(Class<?> container, String name) {
 
   private static Field getField(Class<?> container, String name) {
     while (container != null) {
-      try {
-        Field fld = container.getDeclaredField(name);
-        fld.setAccessible(true);
-        return fld;
-      } catch (NoSuchFieldException ignored) {
-        container = container.getSuperclass();
+      Field[] declaredFields = container.getDeclaredFields();
+      for (int i = 0; i < declaredFields.length; i++) {
+        Field declaredField = declaredFields[i];
+        if (declaredField.getName().equals(name)) {
+          declaredField.setAccessible(true);
+          return declaredField;
+        }
       }
+      container = container.getSuperclass();
     }
     return null;
   }

diff --git a/...p/src/test/java/datadog/trace/bootstrap/debugger/el/ReflectiveFieldValueResolverTest.java b/...p/src/test/java/datadog/trace/bootstrap/debugger/el/ReflectiveFieldValueResolverTest.java
@@ -0,0 +1,29 @@
+package datadog.trace.bootstrap.debugger.el;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class ReflectiveFieldValueResolverTest {
+
+  @Test
+  void getFieldAsCapturedValue() {
+    assertNull(ReflectiveFieldValueResolver.getFieldAsCapturedValue(null, "fieldName").getValue());
+    C c = new C();
+    assertEquals(3, ReflectiveFieldValueResolver.getFieldAsCapturedValue(c, "c1").getValue());
+    assertEquals(1, ReflectiveFieldValueResolver.getFieldAsCapturedValue(c, "a1").getValue());
+    assertEquals("2", ReflectiveFieldValueResolver.getFieldAsCapturedValue(c, "a2").getValue());
+    assertNull(ReflectiveFieldValueResolver.getFieldAsCapturedValue(c, "notExist").getValue());
+  }
+
+  static class A {
+    private int a1 = 1;
+    private String a2 = "2";
+  }
+
+  static class B extends A {}
+
+  static class C extends A {
+    private int c1 = 3;
+  }
+}