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, StackFrameInfo::mid will be set.  This is temporary to enable
  41     // 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     // Set when -XX:-MemberNameInStackFrame
  53     private final int mid;
  54 
  55     // methodName, fileName, and lineNumber will be lazily set by the VM
  56     // when first requested.
  57     private String methodName;
  58     private String fileName = null;     // default for unavailable filename
  59     private int    lineNumber = -1;     // default for unavailable lineNumber
  60 
  61     /*
  62      * Create StackFrameInfo for StackFrameTraverser and LiveStackFrameTraverser
  63      * to use
  64      */
  65     StackFrameInfo(StackWalker walker) {
  66         this.walker = walker;
  67         this.declaringClass = null;
  68         this.mid = 0;
  69         this.bci = -1;
  70         this.memberName = jlInvokeAccess.newMemberName();
  71     }
  72 
  73     @Override
  74     public String getClassName() {
  75         return declaringClass.getName();
  76     }
  77 
  78     @Override
  79     public Class<?> getDeclaringClass() {
  80         walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);
  81         return declaringClass;
  82     }
  83 
  84     // Call the VM to set methodName, lineNumber, and fileName
  85     private synchronized void ensureMethodInfoInitialized() {
  86         if (methodName == null) {
  87             setMethodInfo();
  88         }
  89     }
  90 
  91     @Override
  92     public String getMethodName() {
  93         ensureMethodInfoInitialized();
  94         return methodName;
  95     }
  96 
  97     @Override
  98     public Optional<String> getFileName() {
  99         ensureMethodInfoInitialized();
 100         return fileName != null ? Optional.of(fileName) : Optional.empty();
 101     }
 102 
 103     @Override
 104     public OptionalInt getLineNumber() {
 105         ensureMethodInfoInitialized();
 106         return lineNumber != -1 ? OptionalInt.of(lineNumber) : OptionalInt.empty();
 107     }
 108 
 109     @Override
 110     public boolean isNativeMethod() {
 111         ensureMethodInfoInitialized();
 112         return lineNumber == -2;
 113     }
 114 
 115     @Override
 116     public String toString() {
 117         ensureMethodInfoInitialized();
 118         // same format about StackTraceElement::toString
 119         return getClassName() + "." + getMethodName() +
 120                 (isNativeMethod() ? "(Native Method)" :
 121                         (fileName != null && lineNumber >= 0 ?
 122                                 "(" + fileName + ":" + lineNumber + ")" :
 123                                 (fileName != null ?  "("+fileName+")" : "(Unknown Source)")));
 124     }
 125 
 126     /**
 127      * Lazily initialize method name, file name, line number
 128      */
 129     private native void setMethodInfo();
 130 
 131     /**
 132      * Fill in source file name and line number of the given StackFrame array.
 133      */
 134     static native void fillInStackFrames(int startIndex,
 135                                          Object[] stackframes,
 136                                          int fromIndex, int toIndex);
 137 }