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446 lines
25 KiB
Java
446 lines
25 KiB
Java
/*
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* Copyright (c) 2017, 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang.runtime;
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import java.lang.invoke.ConstantCallSite;
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import java.lang.invoke.MethodHandle;
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import java.lang.invoke.MethodHandles;
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import java.lang.invoke.MethodType;
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import java.lang.invoke.StringConcatFactory;
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import java.lang.invoke.TypeDescriptor;
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import java.security.AccessController;
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import java.security.PrivilegedAction;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Objects;
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import static java.util.Objects.requireNonNull;
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/**
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* Bootstrap methods for state-driven implementations of core methods,
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* including {@link Object#equals(Object)}, {@link Object#hashCode()}, and
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* {@link Object#toString()}. These methods may be used, for example, by
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* Java compiler implementations to implement the bodies of {@link Object}
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* methods for record classes.
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*
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* @since 16
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*/
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public class ObjectMethods {
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private ObjectMethods() { }
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private static final int MAX_STRING_CONCAT_SLOTS = 20;
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private static final MethodType DESCRIPTOR_MT = MethodType.methodType(MethodType.class);
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private static final MethodType NAMES_MT = MethodType.methodType(List.class);
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private static final MethodHandle FALSE = MethodHandles.constant(boolean.class, false);
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private static final MethodHandle TRUE = MethodHandles.constant(boolean.class, true);
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private static final MethodHandle ZERO = MethodHandles.constant(int.class, 0);
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private static final MethodHandle CLASS_IS_INSTANCE;
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private static final MethodHandle OBJECT_EQUALS;
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private static final MethodHandle OBJECTS_EQUALS;
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private static final MethodHandle OBJECTS_HASHCODE;
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private static final MethodHandle OBJECTS_TOSTRING;
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private static final MethodHandle OBJECT_EQ;
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private static final MethodHandle OBJECT_HASHCODE;
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private static final MethodHandle OBJECT_TO_STRING;
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private static final MethodHandle STRING_FORMAT;
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private static final MethodHandle HASH_COMBINER;
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private static final HashMap<Class<?>, MethodHandle> primitiveEquals = new HashMap<>();
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private static final HashMap<Class<?>, MethodHandle> primitiveHashers = new HashMap<>();
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private static final HashMap<Class<?>, MethodHandle> primitiveToString = new HashMap<>();
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static {
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try {
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Class<ObjectMethods> OBJECT_METHODS_CLASS = ObjectMethods.class;
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MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
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MethodHandles.Lookup lookup = MethodHandles.lookup();
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@SuppressWarnings("removal")
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ClassLoader loader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
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@Override public ClassLoader run() { return ClassLoader.getPlatformClassLoader(); }
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});
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CLASS_IS_INSTANCE = publicLookup.findVirtual(Class.class, "isInstance",
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MethodType.methodType(boolean.class, Object.class));
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OBJECT_EQUALS = publicLookup.findVirtual(Object.class, "equals",
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MethodType.methodType(boolean.class, Object.class));
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OBJECT_HASHCODE = publicLookup.findVirtual(Object.class, "hashCode",
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MethodType.fromMethodDescriptorString("()I", loader));
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OBJECT_TO_STRING = publicLookup.findVirtual(Object.class, "toString",
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MethodType.methodType(String.class));
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STRING_FORMAT = publicLookup.findStatic(String.class, "format",
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MethodType.methodType(String.class, String.class, Object[].class));
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OBJECTS_EQUALS = publicLookup.findStatic(Objects.class, "equals",
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MethodType.methodType(boolean.class, Object.class, Object.class));
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OBJECTS_HASHCODE = publicLookup.findStatic(Objects.class, "hashCode",
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MethodType.methodType(int.class, Object.class));
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OBJECTS_TOSTRING = publicLookup.findStatic(Objects.class, "toString",
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MethodType.methodType(String.class, Object.class));
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OBJECT_EQ = lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.methodType(boolean.class, Object.class, Object.class));
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HASH_COMBINER = lookup.findStatic(OBJECT_METHODS_CLASS, "hashCombiner",
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MethodType.fromMethodDescriptorString("(II)I", loader));
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primitiveEquals.put(byte.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(BB)Z", loader)));
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primitiveEquals.put(short.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(SS)Z", loader)));
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primitiveEquals.put(char.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(CC)Z", loader)));
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primitiveEquals.put(int.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(II)Z", loader)));
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primitiveEquals.put(long.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(JJ)Z", loader)));
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primitiveEquals.put(float.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(FF)Z", loader)));
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primitiveEquals.put(double.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(DD)Z", loader)));
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primitiveEquals.put(boolean.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq",
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MethodType.fromMethodDescriptorString("(ZZ)Z", loader)));
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primitiveHashers.put(byte.class, lookup.findStatic(Byte.class, "hashCode",
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MethodType.fromMethodDescriptorString("(B)I", loader)));
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primitiveHashers.put(short.class, lookup.findStatic(Short.class, "hashCode",
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MethodType.fromMethodDescriptorString("(S)I", loader)));
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primitiveHashers.put(char.class, lookup.findStatic(Character.class, "hashCode",
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MethodType.fromMethodDescriptorString("(C)I", loader)));
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primitiveHashers.put(int.class, lookup.findStatic(Integer.class, "hashCode",
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MethodType.fromMethodDescriptorString("(I)I", loader)));
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primitiveHashers.put(long.class, lookup.findStatic(Long.class, "hashCode",
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MethodType.fromMethodDescriptorString("(J)I", loader)));
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primitiveHashers.put(float.class, lookup.findStatic(Float.class, "hashCode",
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MethodType.fromMethodDescriptorString("(F)I", loader)));
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primitiveHashers.put(double.class, lookup.findStatic(Double.class, "hashCode",
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MethodType.fromMethodDescriptorString("(D)I", loader)));
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primitiveHashers.put(boolean.class, lookup.findStatic(Boolean.class, "hashCode",
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MethodType.fromMethodDescriptorString("(Z)I", loader)));
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primitiveToString.put(byte.class, lookup.findStatic(Byte.class, "toString",
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MethodType.methodType(String.class, byte.class)));
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primitiveToString.put(short.class, lookup.findStatic(Short.class, "toString",
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MethodType.methodType(String.class, short.class)));
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primitiveToString.put(char.class, lookup.findStatic(Character.class, "toString",
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MethodType.methodType(String.class, char.class)));
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primitiveToString.put(int.class, lookup.findStatic(Integer.class, "toString",
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MethodType.methodType(String.class, int.class)));
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primitiveToString.put(long.class, lookup.findStatic(Long.class, "toString",
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MethodType.methodType(String.class, long.class)));
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primitiveToString.put(float.class, lookup.findStatic(Float.class, "toString",
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MethodType.methodType(String.class, float.class)));
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primitiveToString.put(double.class, lookup.findStatic(Double.class, "toString",
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MethodType.methodType(String.class, double.class)));
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primitiveToString.put(boolean.class, lookup.findStatic(Boolean.class, "toString",
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MethodType.methodType(String.class, boolean.class)));
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}
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catch (ReflectiveOperationException e) {
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throw new RuntimeException(e);
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}
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}
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private static int hashCombiner(int x, int y) {
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return x*31 + y;
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}
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private static boolean eq(Object a, Object b) { return a == b; }
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private static boolean eq(byte a, byte b) { return a == b; }
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private static boolean eq(short a, short b) { return a == b; }
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private static boolean eq(char a, char b) { return a == b; }
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private static boolean eq(int a, int b) { return a == b; }
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private static boolean eq(long a, long b) { return a == b; }
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private static boolean eq(float a, float b) { return Float.compare(a, b) == 0; }
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private static boolean eq(double a, double b) { return Double.compare(a, b) == 0; }
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private static boolean eq(boolean a, boolean b) { return a == b; }
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/** Get the method handle for combining two values of a given type */
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private static MethodHandle equalator(Class<?> clazz) {
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return (clazz.isPrimitive()
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? primitiveEquals.get(clazz)
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: OBJECTS_EQUALS.asType(MethodType.methodType(boolean.class, clazz, clazz)));
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}
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/** Get the hasher for a value of a given type */
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private static MethodHandle hasher(Class<?> clazz) {
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return (clazz.isPrimitive()
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? primitiveHashers.get(clazz)
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: OBJECTS_HASHCODE.asType(MethodType.methodType(int.class, clazz)));
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}
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/** Get the stringifier for a value of a given type */
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private static MethodHandle stringifier(Class<?> clazz) {
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return (clazz.isPrimitive()
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? primitiveToString.get(clazz)
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: OBJECTS_TOSTRING.asType(MethodType.methodType(String.class, clazz)));
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}
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/**
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* Generates a method handle for the {@code equals} method for a given data class
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* @param receiverClass the data class
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* @param getters the list of getters
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* @return the method handle
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*/
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private static MethodHandle makeEquals(Class<?> receiverClass,
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List<MethodHandle> getters) {
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MethodType rr = MethodType.methodType(boolean.class, receiverClass, receiverClass);
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MethodType ro = MethodType.methodType(boolean.class, receiverClass, Object.class);
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MethodHandle instanceFalse = MethodHandles.dropArguments(FALSE, 0, receiverClass, Object.class); // (RO)Z
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MethodHandle instanceTrue = MethodHandles.dropArguments(TRUE, 0, receiverClass, Object.class); // (RO)Z
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MethodHandle isSameObject = OBJECT_EQ.asType(ro); // (RO)Z
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MethodHandle isInstance = MethodHandles.dropArguments(CLASS_IS_INSTANCE.bindTo(receiverClass), 0, receiverClass); // (RO)Z
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MethodHandle accumulator = MethodHandles.dropArguments(TRUE, 0, receiverClass, receiverClass); // (RR)Z
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for (MethodHandle getter : getters) {
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MethodHandle equalator = equalator(getter.type().returnType()); // (TT)Z
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MethodHandle thisFieldEqual = MethodHandles.filterArguments(equalator, 0, getter, getter); // (RR)Z
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accumulator = MethodHandles.guardWithTest(thisFieldEqual, accumulator, instanceFalse.asType(rr));
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}
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return MethodHandles.guardWithTest(isSameObject,
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instanceTrue,
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MethodHandles.guardWithTest(isInstance, accumulator.asType(ro), instanceFalse));
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}
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/**
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* Generates a method handle for the {@code hashCode} method for a given data class
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* @param receiverClass the data class
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* @param getters the list of getters
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* @return the method handle
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*/
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private static MethodHandle makeHashCode(Class<?> receiverClass,
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List<MethodHandle> getters) {
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MethodHandle accumulator = MethodHandles.dropArguments(ZERO, 0, receiverClass); // (R)I
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// @@@ Use loop combinator instead?
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for (MethodHandle getter : getters) {
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MethodHandle hasher = hasher(getter.type().returnType()); // (T)I
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MethodHandle hashThisField = MethodHandles.filterArguments(hasher, 0, getter); // (R)I
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MethodHandle combineHashes = MethodHandles.filterArguments(HASH_COMBINER, 0, accumulator, hashThisField); // (RR)I
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accumulator = MethodHandles.permuteArguments(combineHashes, accumulator.type(), 0, 0); // adapt (R)I to (RR)I
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}
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return accumulator;
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}
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/**
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* Generates a method handle for the {@code toString} method for a given data class
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* @param receiverClass the data class
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* @param getters the list of getters
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* @param names the names
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* @return the method handle
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*/
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private static MethodHandle makeToString(MethodHandles.Lookup lookup,
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Class<?> receiverClass,
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MethodHandle[] getters,
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List<String> names) {
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assert getters.length == names.size();
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if (getters.length == 0) {
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// special case
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MethodHandle emptyRecordCase = MethodHandles.constant(String.class, receiverClass.getSimpleName() + "[]");
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emptyRecordCase = MethodHandles.dropArguments(emptyRecordCase, 0, receiverClass); // (R)S
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return emptyRecordCase;
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}
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boolean firstTime = true;
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MethodHandle[] mhs;
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List<List<MethodHandle>> splits;
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MethodHandle[] toSplit = getters;
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int namesIndex = 0;
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do {
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/* StringConcatFactory::makeConcatWithConstants can only deal with 200 slots, longs and double occupy two
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* the rest 1 slot, we need to chop the current `getters` into chunks, it could be that for records with
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* a lot of components that we need to do a couple of iterations. The main difference between the first
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* iteration and the rest would be on the recipe
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*/
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splits = split(toSplit);
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mhs = new MethodHandle[splits.size()];
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for (int splitIndex = 0; splitIndex < splits.size(); splitIndex++) {
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String recipe = "";
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if (firstTime && splitIndex == 0) {
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recipe = receiverClass.getSimpleName() + "[";
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}
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for (int i = 0; i < splits.get(splitIndex).size(); i++) {
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recipe += firstTime ? names.get(namesIndex) + "=" + "\1" : "\1";
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if (firstTime && namesIndex != names.size() - 1) {
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recipe += ", ";
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}
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namesIndex++;
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}
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if (firstTime && splitIndex == splits.size() - 1) {
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recipe += "]";
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}
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Class<?>[] concatTypeArgs = new Class<?>[splits.get(splitIndex).size()];
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// special case: no need to create another getters if there is only one split
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MethodHandle[] currentSplitGetters = new MethodHandle[splits.get(splitIndex).size()];
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for (int j = 0; j < splits.get(splitIndex).size(); j++) {
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concatTypeArgs[j] = splits.get(splitIndex).get(j).type().returnType();
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currentSplitGetters[j] = splits.get(splitIndex).get(j);
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}
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MethodType concatMT = MethodType.methodType(String.class, concatTypeArgs);
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try {
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mhs[splitIndex] = StringConcatFactory.makeConcatWithConstants(
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lookup, "",
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concatMT,
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recipe,
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new Object[0]
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).getTarget();
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mhs[splitIndex] = MethodHandles.filterArguments(mhs[splitIndex], 0, currentSplitGetters);
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// this will spread the receiver class across all the getters
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mhs[splitIndex] = MethodHandles.permuteArguments(
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mhs[splitIndex],
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MethodType.methodType(String.class, receiverClass),
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new int[splits.get(splitIndex).size()]
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);
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} catch (Throwable t) {
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throw new RuntimeException(t);
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}
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}
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toSplit = mhs;
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firstTime = false;
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} while (splits.size() > 1);
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return mhs[0];
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}
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/**
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* Chops the getters into smaller chunks according to the maximum number of slots
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* StringConcatFactory::makeConcatWithConstants can chew
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* @param getters the current getters
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* @return chunks that won't surpass the maximum number of slots StringConcatFactory::makeConcatWithConstants can chew
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*/
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private static List<List<MethodHandle>> split(MethodHandle[] getters) {
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List<List<MethodHandle>> splits = new ArrayList<>();
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int slots = 0;
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// Need to peel, so that neither call has more than acceptable number
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// of slots for the arguments.
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List<MethodHandle> cArgs = new ArrayList<>();
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for (MethodHandle methodHandle : getters) {
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Class<?> returnType = methodHandle.type().returnType();
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int needSlots = (returnType == long.class || returnType == double.class) ? 2 : 1;
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if (slots + needSlots > MAX_STRING_CONCAT_SLOTS) {
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splits.add(cArgs);
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cArgs = new ArrayList<>();
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slots = 0;
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}
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cArgs.add(methodHandle);
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slots += needSlots;
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}
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// Flush the tail slice
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if (!cArgs.isEmpty()) {
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splits.add(cArgs);
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}
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return splits;
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}
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/**
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* Bootstrap method to generate the {@link Object#equals(Object)},
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* {@link Object#hashCode()}, and {@link Object#toString()} methods, based
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* on a description of the component names and accessor methods, for either
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* {@code invokedynamic} call sites or dynamic constant pool entries.
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*
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* For more detail on the semantics of the generated methods see the specification
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* of {@link java.lang.Record#equals(Object)}, {@link java.lang.Record#hashCode()} and
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* {@link java.lang.Record#toString()}.
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*
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*
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* @param lookup Every bootstrap method is expected to have a {@code lookup}
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* which usually represents a lookup context with the
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* accessibility privileges of the caller. This is because
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* {@code invokedynamic} call sites always provide a {@code lookup}
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* to the corresponding bootstrap method, but this method just
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* ignores the {@code lookup} parameter
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* @param methodName the name of the method to generate, which must be one of
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* {@code "equals"}, {@code "hashCode"}, or {@code "toString"}
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* @param type a {@link MethodType} corresponding the descriptor type
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* for the method, which must correspond to the descriptor
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* for the corresponding {@link Object} method, if linking
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* an {@code invokedynamic} call site, or the
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* constant {@code MethodHandle.class}, if linking a
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* dynamic constant
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* @param recordClass the record class hosting the record components
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* @param names the list of component names, joined into a string
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* separated by ";", or the empty string if there are no
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* components. This parameter is ignored if the {@code methodName}
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* parameter is {@code "equals"} or {@code "hashCode"}
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* @param getters method handles for the accessor methods for the components
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* @return a call site if invoked by indy, or a method handle
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* if invoked by a condy
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* @throws IllegalArgumentException if the bootstrap arguments are invalid
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* or inconsistent
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* @throws NullPointerException if any argument is {@code null} or if any element
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* in the {@code getters} array is {@code null}
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* @throws Throwable if any exception is thrown during call site construction
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*/
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public static Object bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type,
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Class<?> recordClass,
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String names,
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MethodHandle... getters) throws Throwable {
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requireNonNull(lookup);
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requireNonNull(methodName);
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requireNonNull(type);
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requireNonNull(recordClass);
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requireNonNull(names);
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requireNonNull(getters);
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Arrays.stream(getters).forEach(Objects::requireNonNull);
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MethodType methodType;
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if (type instanceof MethodType mt)
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methodType = mt;
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else {
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methodType = null;
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if (!MethodHandle.class.equals(type))
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throw new IllegalArgumentException(type.toString());
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}
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List<MethodHandle> getterList = List.of(getters);
|
|
MethodHandle handle = switch (methodName) {
|
|
case "equals" -> {
|
|
if (methodType != null && !methodType.equals(MethodType.methodType(boolean.class, recordClass, Object.class)))
|
|
throw new IllegalArgumentException("Bad method type: " + methodType);
|
|
yield makeEquals(recordClass, getterList);
|
|
}
|
|
case "hashCode" -> {
|
|
if (methodType != null && !methodType.equals(MethodType.methodType(int.class, recordClass)))
|
|
throw new IllegalArgumentException("Bad method type: " + methodType);
|
|
yield makeHashCode(recordClass, getterList);
|
|
}
|
|
case "toString" -> {
|
|
if (methodType != null && !methodType.equals(MethodType.methodType(String.class, recordClass)))
|
|
throw new IllegalArgumentException("Bad method type: " + methodType);
|
|
List<String> nameList = "".equals(names) ? List.of() : List.of(names.split(";"));
|
|
if (nameList.size() != getterList.size())
|
|
throw new IllegalArgumentException("Name list and accessor list do not match");
|
|
yield makeToString(lookup, recordClass, getters, nameList);
|
|
}
|
|
default -> throw new IllegalArgumentException(methodName);
|
|
};
|
|
return methodType != null ? new ConstantCallSite(handle) : handle;
|
|
}
|
|
}
|