8011940: java.lang.Class.getAnnotations() always enters synchronized method

Reviewed-by: jfranck, chegar, psandoz, shade

src/share/classes/java/lang/Class.java

@@ -48,6 +48,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Set;
 import java.util.Map;
@@ -2370,11 +2371,14 @@ public final class Class<T> implements java.io.Serializable,
         private static final long reflectionDataOffset;
         // offset of Class.annotationType instance field
         private static final long annotationTypeOffset;
+        // offset of Class.annotationData instance field
+        private static final long annotationDataOffset;
 
         static {
             Field[] fields = Class.class.getDeclaredFields0(false); // bypass caches
             reflectionDataOffset = objectFieldOffset(fields, "reflectionData");
             annotationTypeOffset = objectFieldOffset(fields, "annotationType");
+            annotationDataOffset = objectFieldOffset(fields, "annotationData");
         }
 
         private static long objectFieldOffset(Field[] fields, String fieldName) {
@@ -2396,6 +2400,12 @@ public final class Class<T> implements java.io.Serializable,
                                              AnnotationType newType) {
             return unsafe.compareAndSwapObject(clazz, annotationTypeOffset, oldType, newType);
         }
+
+        static <T> boolean casAnnotationData(Class<?> clazz,
+                                             AnnotationData oldData,
+                                             AnnotationData newData) {
+            return unsafe.compareAndSwapObject(clazz, annotationDataOffset, oldData, newData);
+        }
     }
 
     /**
@@ -2406,7 +2416,7 @@ public final class Class<T> implements java.io.Serializable,
     private static boolean useCaches = true;
 
     // reflection data that might get invalidated when JVM TI RedefineClasses() is called
-    static class ReflectionData<T> {
+    private static class ReflectionData<T> {
         volatile Field[] declaredFields;
         volatile Field[] publicFields;
         volatile Method[] declaredMethods;
@@ -3253,8 +3263,7 @@ public final class Class<T> implements java.io.Serializable,
     public <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
         Objects.requireNonNull(annotationClass);
 
-        initAnnotationsIfNecessary();
-        return (A) annotations.get(annotationClass);
+        return (A) annotationData().annotations.get(annotationClass);
     }
 
     /**
@@ -3275,16 +3284,14 @@ public final class Class<T> implements java.io.Serializable,
     public <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationClass) {
         Objects.requireNonNull(annotationClass);
 
-        initAnnotationsIfNecessary();
-        return AnnotationSupport.getMultipleAnnotations(annotations, annotationClass);
+        return AnnotationSupport.getMultipleAnnotations(annotationData().annotations, annotationClass);
     }
 
     /**
      * @since 1.5
      */
     public Annotation[] getAnnotations() {
-        initAnnotationsIfNecessary();
-        return AnnotationParser.toArray(annotations);
+        return AnnotationParser.toArray(annotationData().annotations);
     }
 
     /**
@@ -3296,8 +3303,7 @@ public final class Class<T> implements java.io.Serializable,
     public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationClass) {
         Objects.requireNonNull(annotationClass);
 
-        initAnnotationsIfNecessary();
-        return (A) declaredAnnotations.get(annotationClass);
+        return (A) annotationData().declaredAnnotations.get(annotationClass);
     }
 
     /**
@@ -3308,52 +3314,85 @@ public final class Class<T> implements java.io.Serializable,
     public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationClass) {
         Objects.requireNonNull(annotationClass);
 
-        initAnnotationsIfNecessary();
-        return AnnotationSupport.getMultipleAnnotations(declaredAnnotations, annotationClass);
+        return AnnotationSupport.getMultipleAnnotations(annotationData().declaredAnnotations, annotationClass);
     }
 
     /**
      * @since 1.5
      */
     public Annotation[] getDeclaredAnnotations()  {
-        initAnnotationsIfNecessary();
-        return AnnotationParser.toArray(declaredAnnotations);
+        return AnnotationParser.toArray(annotationData().declaredAnnotations);
+    }
+
+    // annotation data that might get invalidated when JVM TI RedefineClasses() is called
+    private static class AnnotationData {
+        final Map<Class<? extends Annotation>, Annotation> annotations;
+        final Map<Class<? extends Annotation>, Annotation> declaredAnnotations;
+
+        // Value of classRedefinedCount when we created this AnnotationData instance
+        final int redefinedCount;
+
+        AnnotationData(Map<Class<? extends Annotation>, Annotation> annotations,
+                       Map<Class<? extends Annotation>, Annotation> declaredAnnotations,
+                       int redefinedCount) {
+            this.annotations = annotations;
+            this.declaredAnnotations = declaredAnnotations;
+            this.redefinedCount = redefinedCount;
+        }
     }
 
     // Annotations cache
-    private transient Map<Class<? extends Annotation>, Annotation> annotations;
-    private transient Map<Class<? extends Annotation>, Annotation> declaredAnnotations;
-    // Value of classRedefinedCount when we last cleared the cached annotations and declaredAnnotations fields
-    private  transient int lastAnnotationsRedefinedCount = 0;
-
-    // Clears cached values that might possibly have been obsoleted by
-    // a class redefinition.
-    private void clearAnnotationCachesOnClassRedefinition() {
-        if (lastAnnotationsRedefinedCount != classRedefinedCount) {
-            annotations = declaredAnnotations = null;
-            lastAnnotationsRedefinedCount = classRedefinedCount;
-        }
-    }
-
-    private synchronized void initAnnotationsIfNecessary() {
-        clearAnnotationCachesOnClassRedefinition();
-        if (annotations != null)
-            return;
-        declaredAnnotations = AnnotationParser.parseAnnotations(
-            getRawAnnotations(), getConstantPool(), this);
+    @SuppressWarnings("UnusedDeclaration")
+    private volatile transient AnnotationData annotationData;
+
+    private AnnotationData annotationData() {
+        while (true) { // retry loop
+            AnnotationData annotationData = this.annotationData;
+            int classRedefinedCount = this.classRedefinedCount;
+            if (annotationData != null &&
+                annotationData.redefinedCount == classRedefinedCount) {
+                return annotationData;
+            }
+            // null or stale annotationData -> optimistically create new instance
+            AnnotationData newAnnotationData = createAnnotationData(classRedefinedCount);
+            // try to install it
+            if (Atomic.casAnnotationData(this, annotationData, newAnnotationData)) {
+                // successfully installed new AnnotationData
+                return newAnnotationData;
+            }
+        }
+    }
+
+    private AnnotationData createAnnotationData(int classRedefinedCount) {
+        Map<Class<? extends Annotation>, Annotation> declaredAnnotations =
+            AnnotationParser.parseAnnotations(getRawAnnotations(), getConstantPool(), this);
         Class<?> superClass = getSuperclass();
-        if (superClass == null) {
-            annotations = declaredAnnotations;
-        } else {
-            annotations = new HashMap<>();
-            superClass.initAnnotationsIfNecessary();
-            for (Map.Entry<Class<? extends Annotation>, Annotation> e : superClass.annotations.entrySet()) {
+        Map<Class<? extends Annotation>, Annotation> annotations = null;
+        if (superClass != null) {
+            Map<Class<? extends Annotation>, Annotation> superAnnotations =
+                superClass.annotationData().annotations;
+            for (Map.Entry<Class<? extends Annotation>, Annotation> e : superAnnotations.entrySet()) {
                 Class<? extends Annotation> annotationClass = e.getKey();
-                if (AnnotationType.getInstance(annotationClass).isInherited())
+                if (AnnotationType.getInstance(annotationClass).isInherited()) {
+                    if (annotations == null) { // lazy construction
+                        annotations = new LinkedHashMap<>((Math.max(
+                                declaredAnnotations.size(),
+                                Math.min(12, declaredAnnotations.size() + superAnnotations.size())
+                            ) * 4 + 2) / 3
+                        );
+                    }
                     annotations.put(annotationClass, e.getValue());
+                }
             }
+        }
+        if (annotations == null) {
+            // no inherited annotations -> share the Map with declaredAnnotations
+            annotations = declaredAnnotations;
+        } else {
+            // at least one inherited annotation -> declared may override inherited
             annotations.putAll(declaredAnnotations);
         }
+        return new AnnotationData(annotations, declaredAnnotations, classRedefinedCount);
     }
 
     // Annotation types cache their internal (AnnotationType) form

test/java/lang/annotation/AnnotationsInheritanceOrderRedefinitionTest.java

+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8011940
+ * @summary Test inheritance, order and class redefinition behaviour of RUNTIME
+ *          class annotations
+ * @author plevart
+ */
+
+import sun.reflect.annotation.AnnotationParser;
+
+import java.lang.annotation.Annotation;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.StringJoiner;
+
+public class AnnotationsInheritanceOrderRedefinitionTest {
+
+    @Retention(RetentionPolicy.RUNTIME)
+    @Inherited
+    @interface Ann1 {
+        String value();
+    }
+
+    @Retention(RetentionPolicy.RUNTIME)
+    @Inherited
+    @interface Ann2 {
+        String value();
+    }
+
+    @Retention(RetentionPolicy.RUNTIME)
+    @Inherited
+    @interface Ann3 {
+        String value();
+    }
+
+    @Ann1("A")
+    @Ann2("A")
+    static class A {}
+
+    @Ann3("B")
+    static class B extends A {}
+
+    @Ann1("C")
+    @Ann3("C")
+    static class C extends B {}
+
+    public static void main(String[] args) {
+
+        StringBuilder msgs = new StringBuilder();
+        boolean ok = true;
+
+        ok &= annotationsEqual(msgs, A.class, true,
+            ann(Ann1.class, "A"), ann(Ann2.class, "A"));
+        ok &= annotationsEqual(msgs, A.class, false,
+            ann(Ann1.class, "A"), ann(Ann2.class, "A"));
+        ok &= annotationsEqual(msgs, B.class, true,
+            ann(Ann3.class, "B"));
+        ok &= annotationsEqual(msgs, B.class, false,
+            ann(Ann1.class, "A"), ann(Ann2.class, "A"), ann(Ann3.class, "B"));
+        ok &= annotationsEqual(msgs, C.class, true,
+            ann(Ann1.class, "C"), ann(Ann3.class, "C"));
+        ok &= annotationsEqual(msgs, C.class, false,
+            ann(Ann1.class, "C"), ann(Ann2.class, "A"), ann(Ann3.class, "C"));
+
+        Annotation[] declaredAnnotatiosA = A.class.getDeclaredAnnotations();
+        Annotation[] annotationsA = A.class.getAnnotations();
+        Annotation[] declaredAnnotatiosB = B.class.getDeclaredAnnotations();
+        Annotation[] annotationsB = B.class.getAnnotations();
+        Annotation[] declaredAnnotatiosC = C.class.getDeclaredAnnotations();
+        Annotation[] annotationsC = C.class.getAnnotations();
+
+        incrementClassRedefinedCount(A.class);
+        incrementClassRedefinedCount(B.class);
+        incrementClassRedefinedCount(C.class);
+
+        ok &= annotationsEqualButNotSame(msgs, A.class, true, declaredAnnotatiosA);
+        ok &= annotationsEqualButNotSame(msgs, A.class, false, annotationsA);
+        ok &= annotationsEqualButNotSame(msgs, B.class, true, declaredAnnotatiosB);
+        ok &= annotationsEqualButNotSame(msgs, B.class, false, annotationsB);
+        ok &= annotationsEqualButNotSame(msgs, C.class, true, declaredAnnotatiosC);
+        ok &= annotationsEqualButNotSame(msgs, C.class, false, annotationsC);
+
+        if (!ok) {
+            throw new RuntimeException("test failure\n" + msgs);
+        }
+    }
+
+    // utility methods
+
+    private static boolean annotationsEqualButNotSame(StringBuilder msgs,
+            Class<?> declaringClass, boolean declaredOnly, Annotation[] oldAnns) {
+        if (!annotationsEqual(msgs, declaringClass, declaredOnly, oldAnns)) {
+            return false;
+        }
+        Annotation[] anns = declaredOnly
+                            ? declaringClass.getDeclaredAnnotations()
+                            : declaringClass.getAnnotations();
+        List<Annotation> sameAnns = new ArrayList<>();
+        for (int i = 0; i < anns.length; i++) {
+            if (anns[i] == oldAnns[i]) {
+                sameAnns.add(anns[i]);
+            }
+        }
+        if (!sameAnns.isEmpty()) {
+            msgs.append(declaredOnly ? "declared " : "").append("annotations for ")
+                .append(declaringClass.getSimpleName())
+                .append(" not re-parsed after class redefinition: ")
+                .append(toSimpleString(sameAnns)).append("\n");
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    private static boolean annotationsEqual(StringBuilder msgs,
+            Class<?> declaringClass, boolean declaredOnly, Annotation... expectedAnns) {
+        Annotation[] anns = declaredOnly
+                            ? declaringClass.getDeclaredAnnotations()
+                            : declaringClass.getAnnotations();
+        if (!Arrays.equals(anns, expectedAnns)) {
+            msgs.append(declaredOnly ? "declared " : "").append("annotations for ")
+                .append(declaringClass.getSimpleName()).append(" are: ")
+                .append(toSimpleString(anns)).append(", expected: ")
+                .append(toSimpleString(expectedAnns)).append("\n");
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    private static Annotation ann(Class<? extends Annotation> annotationType,
+                                  Object value) {
+        return AnnotationParser.annotationForMap(annotationType,
+            Collections.singletonMap("value", value));
+    }
+
+    private static String toSimpleString(List<Annotation> anns) {
+        return toSimpleString(anns.toArray(new Annotation[anns.size()]));
+    }
+
+    private static String toSimpleString(Annotation[] anns) {
+        StringJoiner joiner = new StringJoiner(", ");
+        for (Annotation ann : anns) {
+            joiner.add(toSimpleString(ann));
+        }
+        return joiner.toString();
+    }
+
+    private static String toSimpleString(Annotation ann) {
+        Class<? extends Annotation> annotationType = ann.annotationType();
+        Object value;
+        try {
+            value = annotationType.getDeclaredMethod("value").invoke(ann);
+        } catch (IllegalAccessException | InvocationTargetException
+            | NoSuchMethodException e) {
+            throw new RuntimeException(e);
+        }
+        return "@" + annotationType.getSimpleName() + "(" + value + ")";
+    }
+
+    private static final Field classRedefinedCountField;
+
+    static {
+        try {
+            classRedefinedCountField = Class.class.getDeclaredField("classRedefinedCount");
+            classRedefinedCountField.setAccessible(true);
+        } catch (NoSuchFieldException e) {
+            throw new Error(e);
+        }
+    }
+
+    private static void incrementClassRedefinedCount(Class<?> clazz) {
+        try {
+            classRedefinedCountField.set(clazz,
+                ((Integer) classRedefinedCountField.get(clazz)) + 1);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}