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.util.Optional;
  33 import java.util.OptionalInt;
  34 
  35 class StackFrameInfo implements StackFrame {
  36     private final static JavaLangInvokeAccess jlInvokeAccess =
  37         SharedSecrets.getJavaLangInvokeAccess();
  38 
  39     // -XX:+MemberNameInStackFrame will initialize MemberName and all other fields;
  40     // otherwise, VM will set the hidden fields (injected by the VM).
  41     // -XX:+MemberNameInStackFrame is temporary to enable performance measurement
  42     //
  43     // Footprint improvement: MemberName::clazz and MemberName::name
  44     // can replace StackFrameInfo::declaringClass and StackFrameInfo::methodName
  45     // Currently VM sets StackFrameInfo::methodName instead of expanding MemberName::name
  46 
  47     final StackWalker walker;
  48     final Class<?> declaringClass;
  49     final Object memberName;
  50     final int bci;
  51 
  52     // methodName, fileName, and lineNumber will be lazily set by the VM
  53     // when first requested.
  54     private String methodName;
  55     private String fileName = null;     // default for unavailable filename
  56     private int    lineNumber = -1;     // default for unavailable lineNumber
  57 
  58     /*
  59      * Create StackFrameInfo for StackFrameTraverser and LiveStackFrameTraverser
  60      * to use
  61      */
  62     StackFrameInfo(StackWalker walker) {
  63         this.walker = walker;
  64         this.declaringClass = null;
  65         this.bci = -1;
  66         this.memberName = jlInvokeAccess.newMemberName();
  67     }
  68 
  69     @Override
  70     public String getClassName() {
  71         return declaringClass.getName();
  72     }
  73 
  74     @Override
  75     public Class<?> getDeclaringClass() {
  76         walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);
  77         return declaringClass;
  78     }
  79 
  80     // Call the VM to set methodName, lineNumber, and fileName
  81     private synchronized void ensureMethodInfoInitialized() {
  82         if (methodName == null) {
  83             setMethodInfo();
  84         }
  85     }
  86 
  87     @Override
  88     public String getMethodName() {
  89         ensureMethodInfoInitialized();
  90         return methodName;
  91     }
  92 
  93     @Override
  94     public Optional<String> getFileName() {
  95         ensureMethodInfoInitialized();
  96         return fileName != null ? Optional.of(fileName) : Optional.empty();
  97     }
  98 
  99     @Override
 100     public OptionalInt getLineNumber() {
 101         ensureMethodInfoInitialized();
 102         return lineNumber != -1 ? OptionalInt.of(lineNumber) : OptionalInt.empty();
 103     }
 104 
 105     @Override
 106     public boolean isNativeMethod() {
 107         ensureMethodInfoInitialized();
 108         return lineNumber == -2;
 109     }
 110 
 111     @Override
 112     public String toString() {
 113         ensureMethodInfoInitialized();
 114         // similar format as StackTraceElement::toString
 115         if (isNativeMethod()) {
 116             return getClassName() + "." + getMethodName() + "(Native Method)";
 117         } else {
 118             String sep = getLineNumber().isPresent() ? ":" : " bci:";
 119             return getClassName() + "." + getMethodName() +
 120                 "(" + getFileName().orElse("Unknown Source") + sep +
 121                     getLineNumber().orElse(bci) + ")";
 122         }
 123     }
 124 
 125     /**
 126      * Lazily initialize method name, file name, line number
 127      */
 128     private native void setMethodInfo();
 129 
 130     /**
 131      * Fill in source file name and line number of the given StackFrame array.
 132      */
 133     static native void fillInStackFrames(int startIndex,
 134                                          Object[] stackframes,
 135                                          int fromIndex, int toIndex);
 136 }