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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_CLASSFILE_BACKTRACE_HPP
  26 #define SHARE_VM_CLASSFILE_BACKTRACE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "memory/iterator.hpp"
  30 #include "oops/oop.inline.hpp"
  31 
  32 // Backtrace management - Method* on backtraces need to be preserved for
  33 // RedefineClasses, so we keep a list and mark them as on_stack so that the Method*
  34 // doesn't get deallocatd.
  35 // This list is managed as a weak root, but doesn't use jweak because
  36 // the cost of creating these objects is performance critical.
  37 
  38 class Backtrace : public CHeapObj<mtClass> {
  39   oop        _throwable;
  40   Backtrace* _next;
  41 
  42  public:
  43   Backtrace(oop throwable) : _throwable(throwable), _next(NULL) {}
  44   oop throwable()              { return _throwable; }
  45   Backtrace* next() const      { return _next; }
  46   void set_next(Backtrace* bt) { _next = bt; }
  47   // GC support
  48   void oops_do(OopClosure* f);
  49 };
  50 
  51 class BacktraceList : public AllStatic {
  52   // List of backtraces to mark Method pointers.
  53   static Backtrace* _backtraces_head;
  54   static volatile int _bt_count;
  55 
  56  public:
  57   static void mark_on_stack();
  58   static void unlink(BoolObjectClosure* is_alive);
  59   static void add(oop throwable);
  60   static void oops_do(OopClosure* f);
  61 };
  62 
  63 #endif // SHARE_VM_CLASSFILE_BACKTRACE_HPP