--- old/src/share/classes/java/lang/Class.java Sat Feb 22 16:11:21 2014 +++ new/src/share/classes/java/lang/Class.java Sat Feb 22 16:11:19 2014 @@ -1,5 +1,5 @@ /* - * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 1994, 2014, 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 @@ -2338,44 +2338,110 @@ } /** + * Atomic operations support. + */ + private static class Atomic { + // initialize Unsafe machinery here, since we need to call Class.class instance method + // and have to avoid calling it in the static initializer of the Class class... + private static final Unsafe unsafe = Unsafe.getUnsafe(); + // offset of Class.reflectionData instance field + private static final long reflectionDataOffset; + // offset of Class.annotationType instance field + private static final long annotationTypeOffset; + + static { + Field[] fields = Class.class.getDeclaredFields0(false); // bypass caches + reflectionDataOffset = objectFieldOffset(fields, "reflectionData"); + annotationTypeOffset = objectFieldOffset(fields, "annotationType"); + } + + private static long objectFieldOffset(Field[] fields, String fieldName) { + Field field = searchFields(fields, fieldName); + if (field == null) { + throw new Error("No " + fieldName + " field found in java.lang.Class"); + } + return unsafe.objectFieldOffset(field); + } + + static boolean casReflectionData(Class clazz, + SoftReference> oldData, + SoftReference> newData) { + return unsafe.compareAndSwapObject(clazz, reflectionDataOffset, oldData, newData); + } + + static boolean casAnnotationType(Class clazz, + AnnotationType oldType, + AnnotationType newType) { + return unsafe.compareAndSwapObject(clazz, annotationTypeOffset, oldType, newType); + } + } + + /** * Reflection support. */ // Caches for certain reflective results private static boolean useCaches = true; - private volatile transient SoftReference declaredFields; - private volatile transient SoftReference publicFields; - private volatile transient SoftReference declaredMethods; - private volatile transient SoftReference publicMethods; - private volatile transient SoftReference[]> declaredConstructors; - private volatile transient SoftReference[]> publicConstructors; - // Intermediate results for getFields and getMethods - private volatile transient SoftReference declaredPublicFields; - private volatile transient SoftReference declaredPublicMethods; + // reflection data that might get invalidated when JVM TI RedefineClasses() is called + static class ReflectionData { + volatile Field[] declaredFields; + volatile Field[] publicFields; + volatile Method[] declaredMethods; + volatile Method[] publicMethods; + volatile Constructor[] declaredConstructors; + volatile Constructor[] publicConstructors; + // Intermediate results for getFields and getMethods + volatile Field[] declaredPublicFields; + volatile Method[] declaredPublicMethods; + // Value of classRedefinedCount when we created this ReflectionData instance + final int redefinedCount; + + ReflectionData(int redefinedCount) { + this.redefinedCount = redefinedCount; + } + } + + private volatile transient SoftReference> reflectionData; + // Incremented by the VM on each call to JVM TI RedefineClasses() // that redefines this class or a superclass. private volatile transient int classRedefinedCount = 0; - // Value of classRedefinedCount when we last cleared the cached values - // that are sensitive to class redefinition. - private volatile transient int lastRedefinedCount = 0; + // Lazily create and cache ReflectionData + private ReflectionData reflectionData() { + SoftReference> reflectionData = this.reflectionData; + int classRedefinedCount = this.classRedefinedCount; + ReflectionData rd; + if (useCaches && + reflectionData != null && + (rd = reflectionData.get()) != null && + rd.redefinedCount == classRedefinedCount) { + return rd; + } + // else no SoftReference or cleared SoftReference or stale ReflectionData + // -> create and replace new instance + return newReflectionData(reflectionData, classRedefinedCount); + } - // Clears cached values that might possibly have been obsoleted by - // a class redefinition. - private void clearCachesOnClassRedefinition() { - if (lastRedefinedCount != classRedefinedCount) { - declaredFields = publicFields = declaredPublicFields = null; - declaredMethods = publicMethods = declaredPublicMethods = null; - declaredConstructors = publicConstructors = null; - annotations = declaredAnnotations = null; + private ReflectionData newReflectionData(SoftReference> oldReflectionData, + int classRedefinedCount) { + if (!useCaches) return null; - // Use of "volatile" (and synchronization by caller in the case - // of annotations) ensures that no thread sees the update to - // lastRedefinedCount before seeing the caches cleared. - // We do not guard against brief windows during which multiple - // threads might redundantly work to fill an empty cache. - lastRedefinedCount = classRedefinedCount; + while (true) { + ReflectionData rd = new ReflectionData<>(classRedefinedCount); + // try to CAS it... + if (Atomic.casReflectionData(this, oldReflectionData, new SoftReference<>(rd))) { + return rd; + } + // else retry + oldReflectionData = this.reflectionData; + classRedefinedCount = this.classRedefinedCount; + if (oldReflectionData != null && + (rd = oldReflectionData.get()) != null && + rd.redefinedCount == classRedefinedCount) { + return rd; + } } } @@ -2403,7 +2469,7 @@ } // Annotations handling - private native byte[] getRawAnnotations(); + native byte[] getRawAnnotations(); native ConstantPool getConstantPool(); @@ -2418,27 +2484,19 @@ // via ReflectionFactory.copyField. private Field[] privateGetDeclaredFields(boolean publicOnly) { checkInitted(); - Field[] res = null; - if (useCaches) { - clearCachesOnClassRedefinition(); - if (publicOnly) { - if (declaredPublicFields != null) { - res = declaredPublicFields.get(); - } - } else { - if (declaredFields != null) { - res = declaredFields.get(); - } - } + Field[] res; + ReflectionData rd = reflectionData(); + if (rd != null) { + res = publicOnly ? rd.declaredPublicFields : rd.declaredFields; if (res != null) return res; } // No cached value available; request value from VM res = Reflection.filterFields(this, getDeclaredFields0(publicOnly)); - if (useCaches) { + if (rd != null) { if (publicOnly) { - declaredPublicFields = new SoftReference<>(res); + rd.declaredPublicFields = res; } else { - declaredFields = new SoftReference<>(res); + rd.declaredFields = res; } } return res; @@ -2449,12 +2507,10 @@ // via ReflectionFactory.copyField. private Field[] privateGetPublicFields(Set> traversedInterfaces) { checkInitted(); - Field[] res = null; - if (useCaches) { - clearCachesOnClassRedefinition(); - if (publicFields != null) { - res = publicFields.get(); - } + Field[] res; + ReflectionData rd = reflectionData(); + if (rd != null) { + res = rd.publicFields; if (res != null) return res; } @@ -2487,8 +2543,8 @@ res = new Field[fields.size()]; fields.toArray(res); - if (useCaches) { - publicFields = new SoftReference<>(res); + if (rd != null) { + rd.publicFields = res; } return res; } @@ -2511,18 +2567,10 @@ // instead be copied via ReflectionFactory.copyConstructor. private Constructor[] privateGetDeclaredConstructors(boolean publicOnly) { checkInitted(); - Constructor[] res = null; - if (useCaches) { - clearCachesOnClassRedefinition(); - if (publicOnly) { - if (publicConstructors != null) { - res = publicConstructors.get(); - } - } else { - if (declaredConstructors != null) { - res = declaredConstructors.get(); - } - } + Constructor[] res; + ReflectionData rd = reflectionData(); + if (rd != null) { + res = publicOnly ? rd.publicConstructors : rd.declaredConstructors; if (res != null) return res; } // No cached value available; request value from VM @@ -2531,11 +2579,11 @@ } else { res = getDeclaredConstructors0(publicOnly); } - if (useCaches) { + if (rd != null) { if (publicOnly) { - publicConstructors = new SoftReference<>(res); + rd.publicConstructors = res; } else { - declaredConstructors = new SoftReference<>(res); + rd.declaredConstructors = res; } } return res; @@ -2552,27 +2600,19 @@ // via ReflectionFactory.copyMethod. private Method[] privateGetDeclaredMethods(boolean publicOnly) { checkInitted(); - Method[] res = null; - if (useCaches) { - clearCachesOnClassRedefinition(); - if (publicOnly) { - if (declaredPublicMethods != null) { - res = declaredPublicMethods.get(); - } - } else { - if (declaredMethods != null) { - res = declaredMethods.get(); - } - } + Method[] res; + ReflectionData rd = reflectionData(); + if (rd != null) { + res = publicOnly ? rd.declaredPublicMethods : rd.declaredMethods; if (res != null) return res; } // No cached value available; request value from VM res = Reflection.filterMethods(this, getDeclaredMethods0(publicOnly)); - if (useCaches) { + if (rd != null) { if (publicOnly) { - declaredPublicMethods = new SoftReference<>(res); + rd.declaredPublicMethods = res; } else { - declaredMethods = new SoftReference<>(res); + rd.declaredMethods = res; } } return res; @@ -2674,12 +2714,10 @@ // via ReflectionFactory.copyMethod. private Method[] privateGetPublicMethods() { checkInitted(); - Method[] res = null; - if (useCaches) { - clearCachesOnClassRedefinition(); - if (publicMethods != null) { - res = publicMethods.get(); - } + Method[] res; + ReflectionData rd = reflectionData(); + if (rd != null) { + res = rd.publicMethods; if (res != null) return res; } @@ -2727,8 +2765,8 @@ methods.addAllIfNotPresent(inheritedMethods); methods.compactAndTrim(); res = methods.getArray(); - if (useCaches) { - publicMethods = new SoftReference<>(res); + if (rd != null) { + rd.publicMethods = res; } return res; } @@ -2738,7 +2776,7 @@ // Helpers for fetchers of one field, method, or constructor // - private Field searchFields(Field[] fields, String name) { + private static Field searchFields(Field[] fields, String name) { String internedName = name.intern(); for (int i = 0; i < fields.length; i++) { if (fields[i].getName() == internedName) { @@ -2756,7 +2794,7 @@ // of Field objects which have to be created for the common // case where the field being requested is declared in the // class which is being queried. - Field res = null; + Field res; // Search declared public fields if ((res = searchFields(privateGetDeclaredFields(true), name)) != null) { return res; @@ -2808,7 +2846,7 @@ // number of Method objects which have to be created for the // common case where the method being requested is declared in // the class which is being queried. - Method res = null; + Method res; // Search declared public methods if ((res = searchMethods(privateGetDeclaredMethods(true), name, @@ -3209,9 +3247,20 @@ // Annotations cache private transient Map, Annotation> annotations; private transient Map, 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() { - clearCachesOnClassRedefinition(); + clearAnnotationCachesOnClassRedefinition(); if (annotations != null) return; declaredAnnotations = AnnotationParser.parseAnnotations( @@ -3233,10 +3282,11 @@ // Annotation types cache their internal (AnnotationType) form - private AnnotationType annotationType; + @SuppressWarnings("UnusedDeclaration") + private volatile transient AnnotationType annotationType; - void setAnnotationType(AnnotationType type) { - annotationType = type; + boolean casAnnotationType(AnnotationType oldType, AnnotationType newType) { + return Atomic.casAnnotationType(this, oldType, newType); } AnnotationType getAnnotationType() {