diff -r 000000000000 -r c880a8a8803b rt/emul/compact/src/main/java/java/lang/invoke/Stable.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rt/emul/compact/src/main/java/java/lang/invoke/Stable.java Sat Aug 09 11:11:13 2014 +0200 @@ -0,0 +1,73 @@ +/* + * Copyright (c) 2012, 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. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * 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. + */ + +package java.lang.invoke; + +import java.lang.annotation.*; + +/** + * A field may be annotated as stable if all of its component variables + * changes value at most once. + * A field's value counts as its component value. + * If the field is typed as an array, then all the non-null components + * of the array, of depth up to the rank of the field's array type, + * also count as component values. + * By extension, any variable (either array or field) which has annotated + * as stable is called a stable variable, and its non-null or non-zero + * value is called a stable value. + *

+ * Since all fields begin with a default value of null for references + * (resp., zero for primitives), it follows that this annotation indicates + * that the first non-null (resp., non-zero) value stored in the field + * will never be changed. + *

+ * If the field is not of an array type, there are no array elements, + * then the value indicated as stable is simply the value of the field. + * If the dynamic type of the field value is an array but the static type + * is not, the components of the array are not regarded as stable. + *

+ * If the field is an array type, then both the field value and + * all the components of the field value (if the field value is non-null) + * are indicated to be stable. + * If the field type is an array type with rank {@code N > 1}, + * then each component of the field value (if the field value is non-null), + * is regarded as a stable array of rank {@code N-1}. + *

+ * Fields which are declared {@code final} may also be annotated as stable. + * Since final fields already behave as stable values, such an annotation + * indicates no additional information, unless the type of the field is + * an array type. + *

+ * It is (currently) undefined what happens if a field annotated as stable + * is given a third value. In practice, if the JVM relies on this annotation + * to promote a field reference to a constant, it may be that the Java memory + * model would appear to be broken, if such a constant (the second value of the field) + * is used as the value of the field even after the field value has changed. + */ +/* package-private */ +@Target(ElementType.FIELD) +@Retention(RetentionPolicy.RUNTIME) +@interface Stable { +}