1 /*
 2  * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.  Oracle designates this
 8  * particular file as subject to the "Classpath" exception as provided
 9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package jdk.internal.reflect;
27 
28 import java.lang.reflect.*;
29 import jdk.internal.misc.Unsafe;
30 
31 /** Used only for the first few invocations of a Constructor;
32     afterward, switches to bytecode-based implementation */
33 
34 class NativeConstructorAccessorImpl extends ConstructorAccessorImpl {
35     private static final Unsafe U = Unsafe.getUnsafe();
36     private static final long GENERATED_OFFSET
37         = U.objectFieldOffset(NativeConstructorAccessorImpl.class, "generated");
38 
39     private final Constructor<?> c;
40     private final DelegatingConstructorAccessorImpl parent;
41     private int numInvocations;
42     private volatile int generated;
43 
44     NativeConstructorAccessorImpl(Constructor<?> c) {
45         this.c = c;
46         this.parent = new DelegatingConstructorAccessorImpl(this);
47     }
48 
49     public Object newInstance(Object[] args)
50         throws InstantiationException,
51                IllegalArgumentException,
52                InvocationTargetException
53     {
54         // We can't inflate a constructor belonging to a hidden class
55         // because that kind of class can't be referred to by name, hence can't
56         // be found from the generated bytecode.
57         if (++numInvocations > ReflectionFactory.inflationThreshold()
58                 && !c.getDeclaringClass().isHidden()
59                 && generated == 0
60                 && U.compareAndSetInt(this, GENERATED_OFFSET, 0, 1)) {
61             try {
62                 ConstructorAccessorImpl acc = (ConstructorAccessorImpl)
63                     new MethodAccessorGenerator().
64                         generateConstructor(c.getDeclaringClass(),
65                                             c.getParameterTypes(),
66                                             c.getExceptionTypes(),
67                                             c.getModifiers());
68                 parent.setDelegate(acc);
69             } catch (Throwable t) {
70                 // Throwable happens in generateConstructor, restore generated to 0
71                 generated = 0;
72                 throw t;
73             }
74         }
75 
76         return newInstance0(c, args);
77     }
78 
79     DelegatingConstructorAccessorImpl getParent() {
80         return parent;
81     }
82 
83     private static native Object newInstance0(Constructor<?> c, Object[] args)
84         throws InstantiationException,
85                IllegalArgumentException,
86                InvocationTargetException;
87 }