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.
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  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   // initialize
  39   virtual bool init() = 0;
  40   // clean-up
  41   virtual void done() = 0;
  42 
  43   // mark an object if not yet marked.
  44   // return true if the oop is marked by this call
  45   virtual bool mark(oop o) = 0;
  46   // check if the object has been
  47   virtual bool marked(oop o) = 0;
  48 
  49   bool needs_reset() const      { return _needs_reset; }
  50   void set_needs_reset(bool v)  { _needs_reset = v; }
  51 };
  52 
  53 // Default implementation
  54 class DefaultObjectMarker : public ObjectMarker {
  55  private:
  56   // saved headers
  57   GrowableArray<oop>* _saved_oop_stack;
  58   GrowableArray<markWord>* _saved_mark_stack;
  59 
  60  public:
  61   DefaultObjectMarker();
  62   bool init();
  63   void done();
  64 
  65   bool mark(oop o);
  66   bool marked(oop o);
  67 };
  68 
  69 #endif // SHARE_GC_SHARED_OBJECTMARKER_HPP