1 /*
   2  * Copyright (c) 2015, 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 package java.lang;
  26 
  27 import jdk.internal.misc.JavaLangInvokeAccess;
  28 import jdk.internal.misc.SharedSecrets;
  29 
  30 import static java.lang.StackWalker.Option.*;
  31 import java.lang.StackWalker.StackFrame;
  32 import java.lang.reflect.Module;
  33 import java.util.Optional;
  34 import java.util.OptionalInt;
  35 
  36 class StackFrameInfo implements StackFrame {
  37     private final static JavaLangInvokeAccess jlInvokeAccess =
  38         SharedSecrets.getJavaLangInvokeAccess();
  39 
  40     // Footprint improvement: MemberName::clazz can replace
  41     // StackFrameInfo::declaringClass.
  42 
  43     final StackWalker walker;
  44     final Class<?> declaringClass;
  45     final Object memberName;
  46     final short bci;
  47     private volatile StackTraceElement ste;
  48 
  49     /*
  50      * Create StackFrameInfo for StackFrameTraverser and LiveStackFrameTraverser
  51      * to use
  52      */
  53     StackFrameInfo(StackWalker walker) {
  54         this.walker = walker;
  55         this.declaringClass = null;
  56         this.bci = -1;
  57         this.memberName = jlInvokeAccess.newMemberName();
  58     }
  59 
  60     @Override
  61     public String getClassName() {
  62         return declaringClass.getName();
  63     }
  64 
  65     @Override
  66     public Class<?> getDeclaringClass() {
  67         walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);
  68         return declaringClass;
  69     }
  70 
  71     @Override
  72     public String getMethodName() {
  73         return jlInvokeAccess.getName(memberName);
  74     }
  75 
  76     @Override
  77     public final Optional<String> getFileName() {
  78         StackTraceElement ste = toStackTraceElement();
  79         return ste.getFileName() != null ? Optional.of(ste.getFileName()) : Optional.empty();
  80     }
  81 
  82     @Override
  83     public final OptionalInt getLineNumber() {
  84         StackTraceElement ste = toStackTraceElement();
  85         return ste.getLineNumber() > 0 ? OptionalInt.of(ste.getLineNumber()) : OptionalInt.empty();
  86     }
  87 
  88     @Override
  89     public final boolean isNativeMethod() {
  90         StackTraceElement ste = toStackTraceElement();
  91         return ste.isNativeMethod();
  92     }
  93 
  94     @Override
  95     public String toString() {
  96         StackTraceElement ste = toStackTraceElement();
  97         return ste.toString();
  98     }
  99 
 100     /**
 101      * Fill in the fields of the given StackTraceElement
 102      */
 103     private native void toStackTraceElement0(StackTraceElement ste);
 104 
 105     @Override
 106     public StackTraceElement toStackTraceElement() {
 107         StackTraceElement s = ste;
 108         if (s == null) {
 109             synchronized (this) {
 110                 s = ste;
 111                 if (s == null) {
 112                     s = new StackTraceElement();
 113                     toStackTraceElement0(s);
 114                     ste = s;
 115                 }
 116             }
 117         }
 118         return s;
 119     }
 120 }