/*
* Copyright (c) 2012, 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
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*/
package java.lang.invoke;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.concurrent.atomic.AtomicInteger;
import jdk.internal.org.objectweb.asm.*;
import static jdk.internal.org.objectweb.asm.Opcodes.*;
import sun.misc.Unsafe;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Lambda metafactory implementation which dynamically creates an inner-class-like class per lambda callsite.
*
* @see LambdaMetafactory
*/
/* package */ final class InnerClassLambdaMetafactory extends AbstractValidatingLambdaMetafactory {
private static final int CLASSFILE_VERSION = 51;
private static final String METHOD_DESCRIPTOR_VOID = Type.getMethodDescriptor(Type.VOID_TYPE);
private static final String NAME_MAGIC_ACCESSOR_IMPL = "java/lang/invoke/MagicLambdaImpl";
private static final String NAME_CTOR = "<init>";
//Serialization support
private static final String NAME_SERIALIZED_LAMBDA = "java/lang/invoke/SerializedLambda";
private static final String DESCR_METHOD_WRITE_REPLACE = "()Ljava/lang/Object;";
private static final String NAME_METHOD_WRITE_REPLACE = "writeReplace";
private static final String NAME_OBJECT = "java/lang/Object";
private static final String DESCR_CTOR_SERIALIZED_LAMBDA
= MethodType.methodType(void.class,
Class.class,
int.class, String.class, String.class, String.class,
int.class, String.class, String.class, String.class,
String.class,
Object[].class).toMethodDescriptorString();
// Used to ensure that each spun class name is unique
private static final AtomicInteger counter = new AtomicInteger(0);
// See context values in AbstractValidatingLambdaMetafactory
private final String implMethodClassName; // Name of type containing implementation "CC"
private final String implMethodName; // Name of implementation method "impl"
private final String implMethodDesc; // Type descriptor for implementation methods "(I)Ljava/lang/String;"
private final Type[] implMethodArgumentTypes; // ASM types for implementaion method parameters
private final Type implMethodReturnType; // ASM type for implementaion method return type "Ljava/lang/String;"
private final MethodType constructorType; // Generated class constructor type "(CC)void"
private final String constructorDesc; // Type descriptor for constructor "(LCC;)V"
private final ClassWriter cw; // ASM class writer
private final Type[] argTypes; // ASM types for the constructor arguments
private final String[] argNames; // Generated names for the constructor arguments
private final String lambdaClassName; // Generated name for the generated class "X$$Lambda$1"
private final Type[] instantiatedArgumentTypes; // ASM types for the functional interface arguments
/**
* General meta-factory constructor, standard cases and allowing for uncommon options such as serialization.
*
* @param caller Stacked automatically by VM; represents a lookup context with the accessibility privileges
* of the caller.
* @param invokedType Stacked automatically by VM; the signature of the invoked method, which includes the
* expected static type of the returned lambda object, and the static types of the captured
* arguments for the lambda. In the event that the implementation method is an instance method,
* the first argument in the invocation signature will correspond to the receiver.
* @param samMethod The primary method in the functional interface to which the lambda or method reference is
* being converted, represented as a method handle.
* @param implMethod The implementation method which should be called (with suitable adaptation of argument
* types, return types, and adjustment for captured arguments) when methods of the resulting
* functional interface instance are invoked.
* @param instantiatedMethodType The signature of the primary functional interface method after type variables
* are substituted with their instantiation from the capture site
* @param flags A bitmask containing flags that may influence the translation of this lambda expression. Defined
* fields include FLAG_SERIALIZABLE.
* @param markerInterfaces Additional interfaces which the lambda object should implement.
* @throws ReflectiveOperationException
* @throws LambdaConversionException If any of the meta-factory protocol invariants are violated
*/
public InnerClassLambdaMetafactory(MethodHandles.Lookup caller,
MethodType invokedType,
MethodHandle samMethod,
MethodHandle implMethod,
MethodType instantiatedMethodType,
int flags,
Class<?>[] markerInterfaces)
throws ReflectiveOperationException, LambdaConversionException {
super(caller, invokedType, samMethod, implMethod, instantiatedMethodType, flags, markerInterfaces);
implMethodClassName = implDefiningClass.getName().replace('.', '/');
implMethodName = implInfo.getName();
implMethodDesc = implMethodType.toMethodDescriptorString();
Type implMethodAsmType = Type.getMethodType(implMethodDesc);
implMethodArgumentTypes = implMethodAsmType.getArgumentTypes();
implMethodReturnType = (implKind == MethodHandleInfo.REF_newInvokeSpecial)
? Type.getObjectType(implMethodClassName)
: implMethodAsmType.getReturnType();
constructorType = invokedType.changeReturnType(Void.TYPE);
constructorDesc = constructorType.toMethodDescriptorString();
lambdaClassName = targetClass.getName().replace('.', '/') + "$$Lambda$" + counter.incrementAndGet();
cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
argTypes = Type.getArgumentTypes(constructorDesc);
argNames = new String[argTypes.length];
for (int i = 0; i < argTypes.length; i++) {
argNames[i] = "arg$" + (i + 1);
}
instantiatedArgumentTypes = Type.getArgumentTypes(instantiatedMethodType.toMethodDescriptorString());
}
/**
* Build the CallSite. Generate a class file which implements the functional
* interface, define the class, if there are no parameters create an instance
* of the class which the CallSite will return, otherwise, generate handles
* which will call the class' constructor.
*
* @return a CallSite, which, when invoked, will return an instance of the
* functional interface
* @throws ReflectiveOperationException
* @throws LambdaConversionException If properly formed functional interface is not found
*/
@Override
CallSite buildCallSite() throws ReflectiveOperationException, LambdaConversionException {
final Class<?> innerClass = spinInnerClass();
if (invokedType.parameterCount() == 0) {
final Constructor[] ctrs = AccessController.doPrivileged(
new PrivilegedAction<Constructor[]>() {
@Override
public Constructor[] run() {
return innerClass.getDeclaredConstructors();
}
});
if (ctrs.length != 1) {
throw new ReflectiveOperationException("Expected one lambda constructor for "
+ innerClass.getCanonicalName() + ", got " + ctrs.length);
}
// The lambda implementing inner class constructor is private, set
// it accessible (by us) before creating the constant sole instance
AccessController.doPrivileged(new PrivilegedAction<Void>() {
@Override
public Void run() {
ctrs[0].setAccessible(true);
return null;
}
});
Object inst = ctrs[0].newInstance();
return new ConstantCallSite(MethodHandles.constant(samBase, inst));
} else {
return new ConstantCallSite(
MethodHandles.Lookup.IMPL_LOOKUP
.findConstructor(innerClass, constructorType)
.asType(constructorType.changeReturnType(samBase)));
}
}
/**
* Generate a class file which implements the functional
* interface, define and return the class.
*
* @return a Class which implements the functional interface
* @throws LambdaConversionException If properly formed functional interface is not found
*/
private Class<?> spinInnerClass() throws LambdaConversionException {
String samName = samBase.getName().replace('.', '/');
String[] interfaces = new String[markerInterfaces.length + 1];
interfaces[0] = samName;
for (int i=0; i<markerInterfaces.length; i++) {
interfaces[i+1] = markerInterfaces[i].getName().replace('.', '/');
}
cw.visit(CLASSFILE_VERSION, ACC_SUPER + ACC_FINAL + ACC_SYNTHETIC,
lambdaClassName, null,
NAME_MAGIC_ACCESSOR_IMPL, interfaces);
// Generate final fields to be filled in by constructor
for (int i = 0; i < argTypes.length; i++) {
FieldVisitor fv = cw.visitField(ACC_PRIVATE + ACC_FINAL, argNames[i], argTypes[i].getDescriptor(),
null, null);
fv.visitEnd();
}
generateConstructor();
MethodAnalyzer ma = new MethodAnalyzer();
// Forward the SAM method
if (ma.getSamMethod() == null) {
throw new LambdaConversionException(String.format("Functional interface method not found: %s", samMethodType));
} else {
generateForwardingMethod(ma.getSamMethod(), false);
}
// Forward the bridges
// @@@ The commented-out code is temporary, pending the VM's ability to bridge all methods on request
// @@@ Once the VM can do fail-over, uncomment the !ma.wasDefaultMethodFound() test, and emit the appropriate
// @@@ classfile attribute to request custom bridging. See 8002092.
if (!ma.getMethodsToBridge().isEmpty() /* && !ma.conflictFoundBetweenDefaultAndBridge() */ ) {
for (Method m : ma.getMethodsToBridge()) {
generateForwardingMethod(m, true);
}
}
if (isSerializable) {
generateWriteReplace();
}
cw.visitEnd();
// Define the generated class in this VM.
final byte[] classBytes = cw.toByteArray();
/*** Uncomment to dump the generated file
System.out.printf("Loaded: %s (%d bytes) %n", lambdaClassName, classBytes.length);
try (FileOutputStream fos = new FileOutputStream(lambdaClassName.replace('/', '.') + ".class")) {
fos.write(classBytes);
} catch (IOException ex) {
PlatformLogger.getLogger(InnerClassLambdaMetafactory.class.getName()).severe(ex.getMessage(), ex);
}
***/
ClassLoader loader = targetClass.getClassLoader();
ProtectionDomain pd = (loader == null)
? null
: AccessController.doPrivileged(
new PrivilegedAction<ProtectionDomain>() {
@Override
public ProtectionDomain run() {
return targetClass.getProtectionDomain();
}
}
);
return (Class<?>) Unsafe.getUnsafe().defineClass(lambdaClassName, classBytes, 0, classBytes.length,
loader, pd);
}
/**
* Generate the constructor for the class
*/
private void generateConstructor() {
// Generate constructor
MethodVisitor ctor = cw.visitMethod(ACC_PRIVATE, NAME_CTOR, constructorDesc, null, null);
ctor.visitCode();
ctor.visitVarInsn(ALOAD, 0);
ctor.visitMethodInsn(INVOKESPECIAL, NAME_MAGIC_ACCESSOR_IMPL, NAME_CTOR, METHOD_DESCRIPTOR_VOID);
int lvIndex = 0;
for (int i = 0; i < argTypes.length; i++) {
ctor.visitVarInsn(ALOAD, 0);
ctor.visitVarInsn(argTypes[i].getOpcode(ILOAD), lvIndex + 1);
lvIndex += argTypes[i].getSize();
ctor.visitFieldInsn(PUTFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());
}
ctor.visitInsn(RETURN);
ctor.visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored
ctor.visitEnd();
}
/**
* Generate the writeReplace method (if needed for serialization)
*/
private void generateWriteReplace() {
TypeConvertingMethodAdapter mv
= new TypeConvertingMethodAdapter(cw.visitMethod(ACC_PRIVATE + ACC_FINAL,
NAME_METHOD_WRITE_REPLACE, DESCR_METHOD_WRITE_REPLACE,
null, null));
mv.visitCode();
mv.visitTypeInsn(NEW, NAME_SERIALIZED_LAMBDA);
mv.visitInsn(DUP);;
mv.visitLdcInsn(Type.getType(targetClass));
mv.visitLdcInsn(samInfo.getReferenceKind());
mv.visitLdcInsn(invokedType.returnType().getName().replace('.', '/'));
mv.visitLdcInsn(samInfo.getName());
mv.visitLdcInsn(samInfo.getMethodType().toMethodDescriptorString());
mv.visitLdcInsn(implInfo.getReferenceKind());
mv.visitLdcInsn(implInfo.getDeclaringClass().getName().replace('.', '/'));
mv.visitLdcInsn(implInfo.getName());
mv.visitLdcInsn(implInfo.getMethodType().toMethodDescriptorString());
mv.visitLdcInsn(instantiatedMethodType.toMethodDescriptorString());
mv.iconst(argTypes.length);
mv.visitTypeInsn(ANEWARRAY, NAME_OBJECT);
for (int i = 0; i < argTypes.length; i++) {
mv.visitInsn(DUP);
mv.iconst(i);
mv.visitVarInsn(ALOAD, 0);
mv.visitFieldInsn(GETFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());
mv.boxIfTypePrimitive(argTypes[i]);
mv.visitInsn(AASTORE);
}
mv.visitMethodInsn(INVOKESPECIAL, NAME_SERIALIZED_LAMBDA, NAME_CTOR,
DESCR_CTOR_SERIALIZED_LAMBDA);
mv.visitInsn(ARETURN);
mv.visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored
mv.visitEnd();
}
/**
* Generate a method which calls the lambda implementation method,
* converting arguments, as needed.
* @param m The method whose signature should be generated
* @param isBridge True if this methods should be flagged as a bridge
*/
private void generateForwardingMethod(Method m, boolean isBridge) {
Class<?>[] exceptionTypes = m.getExceptionTypes();
String[] exceptionNames = new String[exceptionTypes.length];
for (int i = 0; i < exceptionTypes.length; i++) {
exceptionNames[i] = exceptionTypes[i].getName().replace('.', '/');
}
String methodDescriptor = Type.getMethodDescriptor(m);
int access = isBridge? ACC_PUBLIC | ACC_BRIDGE : ACC_PUBLIC;
MethodVisitor mv = cw.visitMethod(access, m.getName(), methodDescriptor, null, exceptionNames);
new ForwardingMethodGenerator(mv).generate(m);
}
/**
* This class generates a method body which calls the lambda implementation
* method, converting arguments, as needed.
*/
private class ForwardingMethodGenerator extends TypeConvertingMethodAdapter {
ForwardingMethodGenerator(MethodVisitor mv) {
super(mv);
}
void generate(Method m) throws InternalError {
visitCode();
if (implKind == MethodHandleInfo.REF_newInvokeSpecial) {
visitTypeInsn(NEW, implMethodClassName);
visitInsn(DUP);;
}
for (int i = 0; i < argTypes.length; i++) {
visitVarInsn(ALOAD, 0);
visitFieldInsn(GETFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());
}
convertArgumentTypes(Type.getArgumentTypes(m));
// Invoke the method we want to forward to
visitMethodInsn(invocationOpcode(), implMethodClassName, implMethodName, implMethodDesc);
// Convert the return value (if any) and return it
// Note: if adapting from non-void to void, the 'return' instruction will pop the unneeded result
Type samReturnType = Type.getReturnType(m);
convertType(implMethodReturnType, samReturnType, samReturnType);
visitInsn(samReturnType.getOpcode(Opcodes.IRETURN));
visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored
visitEnd();
}
private void convertArgumentTypes(Type[] samArgumentTypes) {
int lvIndex = 0;
boolean samIncludesReceiver = implIsInstanceMethod && argTypes.length == 0;
int samReceiverLength = samIncludesReceiver ? 1 : 0;
if (samIncludesReceiver) {
// push receiver
Type rcvrType = samArgumentTypes[0];
Type instantiatedRcvrType = instantiatedArgumentTypes[0];
visitVarInsn(rcvrType.getOpcode(ILOAD), lvIndex + 1);
lvIndex += rcvrType.getSize();
convertType(rcvrType, Type.getType(implDefiningClass), instantiatedRcvrType);
}
int argOffset = implMethodArgumentTypes.length - samArgumentTypes.length;
for (int i = samReceiverLength; i < samArgumentTypes.length; i++) {
Type argType = samArgumentTypes[i];
Type targetType = implMethodArgumentTypes[argOffset + i];
Type instantiatedArgType = instantiatedArgumentTypes[i];
visitVarInsn(argType.getOpcode(ILOAD), lvIndex + 1);
lvIndex += argType.getSize();
convertType(argType, targetType, instantiatedArgType);
}
}
private void convertType(Type argType, Type targetType, Type functionalType) {
convertType(argType.getDescriptor(), targetType.getDescriptor(), functionalType.getDescriptor());
}
private int invocationOpcode() throws InternalError {
switch (implKind) {
case MethodHandleInfo.REF_invokeStatic:
return INVOKESTATIC;
case MethodHandleInfo.REF_newInvokeSpecial:
return INVOKESPECIAL;
case MethodHandleInfo.REF_invokeVirtual:
return INVOKEVIRTUAL;
case MethodHandleInfo.REF_invokeInterface:
return INVOKEINTERFACE;
case MethodHandleInfo.REF_invokeSpecial:
return INVOKESPECIAL;
default:
throw new InternalError("Unexpected invocation kind: " + implKind);
}
}
}
}