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 > 0 ? 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             // avoid allocating Optional objects

   119             return getClassName() + "." + getMethodName() +

   120                 "(" + (fileName != null ? fileName : "Unknown Source") +

   121                       (lineNumber > 0 ? ":" + lineNumber : " bci:" + 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 }