1 /*
   2  * Copyright (c) 2020, 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_GC_SHARED_OBJECTMARKER_HPP
  26 #define SHARE_GC_SHARED_OBJECTMARKER_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "oops/markWord.hpp"
  30 #include "utilities/growableArray.hpp"
  31 
  32 // ObjectMarker is used to support JVMTI for marking objects when walking the
  33 // heap.
  34 class ObjectMarker : public CHeapObj<mtInternal> {
  35 protected:
  36   bool _needs_reset;
  37 public:
  38   virtual bool init() = 0;                       // initialize
  39   virtual void done() = 0;                       // clean-up
  40 
  41   // mark an object if not yet marked.
  42   // return true if the oop is marked by this call
  43   virtual bool mark(oop o) = 0;
  44   virtual bool visited(oop o) = 0;        // check if object has been visited
  45 
  46   bool needs_reset() const      { return _needs_reset; }
  47   void set_needs_reset(bool v)  { _needs_reset = v; }
  48 };
  49 
  50 // ObjectMarker provides the mark and visited functions
  51 class DefaultObjectMarker : public ObjectMarker {
  52  private:
  53   // saved headers
  54   GrowableArray<oop>* _saved_oop_stack;
  55   GrowableArray<markWord>* _saved_mark_stack;
  56 
  57  public:
  58   DefaultObjectMarker();
  59   bool init();
  60   void done();
  61 
  62   bool mark(oop o);
  63   bool visited(oop o);
  64 };
  65 
  66 #endif // SHARE_GC_SHARED_OBJECTMARKER_HPP