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 /*

  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP

 #include "gc_interface/collectedHeap.hpp"

 #include "memory/universe.hpp"

 #include "oops/markOop.hpp"

 #include "oops/oop.hpp"

 #include "runtime/timer.hpp"

 #include "utilities/growableArray.hpp"

 #include "utilities/stack.hpp"

 #include "utilities/taskqueue.hpp"

 class ReferenceProcessor;

 class DataLayout;

 // MarkSweep takes care of global mark-compact garbage collection for a

 // GenCollectedHeap using a four-phase pointer forwarding algorithm.  All

 // generations are assumed to support marking; those that can also support

 // compaction.

 //

 // Class unloading will only occur when a full gc is invoked.

 // declared at end

 class PreservedMark;

 class MarkSweep : AllStatic {

   //

   // Inline closure decls

   //

   class FollowRootClosure: public OopsInGenClosure {

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   class MarkAndPushClosure: public OopClosure {

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   // The one and only place to start following the classes.

   // Should only be applied to the ClassLoaderData klasses list.

   class FollowKlassClosure : public KlassClosure {

    public:

     void do_klass(Klass* klass);

   };

   class AdjustKlassClosure : public KlassClosure {

    public:

     void do_klass(Klass* klass);

   };

   class FollowStackClosure: public VoidClosure {

    public:

     virtual void do_void();

   };

   class AdjustPointerClosure: public OopsInGenClosure {

    private:

     bool _is_root;

    public:

     AdjustPointerClosure(bool is_root) : _is_root(is_root) {}

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   // Used for java/lang/ref handling

   class IsAliveClosure: public BoolObjectClosure {

    public:

     virtual void do_object(oop p);

     virtual bool do_object_b(oop p);

   };

   class KeepAliveClosure: public OopClosure {

    protected:

     template <class T> void do_oop_work(T* p);

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   //

   // Friend decls

   //

   friend class AdjustPointerClosure;

   friend class KeepAliveClosure;

   friend class VM_MarkSweep;

   friend void marksweep_init();

   //

   // Vars

   //

  protected:

   // Total invocations of a MarkSweep collection

   static unsigned int _total_invocations;

   // Traversal stacks used during phase1

   static Stack<oop, mtGC>                      _marking_stack;

   static Stack<ObjArrayTask, mtGC>             _objarray_stack;

   // Space for storing/restoring mark word

   static Stack<markOop, mtGC>                  _preserved_mark_stack;

   static Stack<oop, mtGC>                      _preserved_oop_stack;

   static size_t                          _preserved_count;

   static size_t                          _preserved_count_max;

   static PreservedMark*                  _preserved_marks;

   // Reference processing (used in ...follow_contents)

   static ReferenceProcessor*             _ref_processor;

   // Non public closures

   static KeepAliveClosure keep_alive;

   // Debugging

   static void trace(const char* msg) PRODUCT_RETURN;

  public:

   // Public closures

   static IsAliveClosure       is_alive;

   static FollowRootClosure    follow_root_closure;

   static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure

   static MarkAndPushClosure   mark_and_push_closure;

   static FollowKlassClosure   follow_klass_closure;

   static FollowStackClosure   follow_stack_closure;

   static AdjustPointerClosure adjust_root_pointer_closure;

   static AdjustPointerClosure adjust_pointer_closure;

   static AdjustKlassClosure   adjust_klass_closure;

   // Accessors

   static unsigned int total_invocations() { return _total_invocations; }

   // Reference Processing

   static ReferenceProcessor* const ref_processor() { return _ref_processor; }

   // Call backs for marking

   static void mark_object(oop obj);

   // Mark pointer and follow contents.  Empty marking stack afterwards.

   template <class T> static inline void follow_root(T* p);

   // Check mark and maybe push on marking stack

   template <class T> static void mark_and_push(T* p);

   static inline void push_objarray(oop obj, size_t index);

   static void follow_stack();   // Empty marking stack.

   static void follow_klass(Klass* klass);

   static void adjust_klass(Klass* klass);

   static void follow_class_loader(ClassLoaderData* cld);

   static void adjust_class_loader(ClassLoaderData* cld);

   static void preserve_mark(oop p, markOop mark);

                                 // Save the mark word so it can be restored later

   static void adjust_marks();   // Adjust the pointers in the preserved marks table

   static void restore_marks();  // Restore the marks that we saved in preserve_mark

   template <class T> static inline void adjust_pointer(T* p, bool isroot);

   static void adjust_root_pointer(oop* p)  { adjust_pointer(p, true); }

   static void adjust_pointer(oop* p)       { adjust_pointer(p, false); }

   static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }

 };

 class PreservedMark VALUE_OBJ_CLASS_SPEC {

 private:

   oop _obj;

   markOop _mark;

 public:

   void init(oop obj, markOop mark) {

     _obj = obj;

     _mark = mark;

   }

   void adjust_pointer() {

     MarkSweep::adjust_pointer(&_obj);

   }

   void restore() {

     _obj->set_mark(_mark);

   }

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP