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 /*

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

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  * 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.

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

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP

 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"

 #include "gc_implementation/parallelScavenge/psVirtualspace.hpp"

 #include "gc_implementation/shared/collectorCounters.hpp"

 #include "memory/allocation.hpp"

 #include "oops/oop.hpp"

 #include "utilities/stack.hpp"

 class GCTaskManager;

 class GCTaskQueue;

 class OopStack;

 class ReferenceProcessor;

 class ParallelScavengeHeap;

 class PSIsAliveClosure;

 class PSRefProcTaskExecutor;

 class PSScavenge: AllStatic {

   friend class PSIsAliveClosure;

   friend class PSKeepAliveClosure;

   friend class PSPromotionManager;

  enum ScavengeSkippedCause {

    not_skipped = 0,

    to_space_not_empty,

    promoted_too_large,

    full_follows_scavenge

  };

   // Saved value of to_space->top(), used to prevent objects in to_space from

   // being rescanned.

   static HeapWord* _to_space_top_before_gc;

   // Number of consecutive attempts to scavenge that were skipped

   static int                _consecutive_skipped_scavenges;

  protected:

   // Flags/counters

   static ReferenceProcessor* _ref_processor;        // Reference processor for scavenging.

   static PSIsAliveClosure    _is_alive_closure;     // Closure used for reference processing

   static CardTableExtension* _card_table;           // We cache the card table for fast access.

   static bool                _survivor_overflow;    // Overflow this collection

   static int                 _tenuring_threshold;   // tenuring threshold for next scavenge

   static elapsedTimer        _accumulated_time;     // total time spent on scavenge

   static HeapWord*           _young_generation_boundary; // The lowest address possible for the young_gen.

                                                          // This is used to decide if an oop should be scavenged,

                                                          // cards should be marked, etc.

   static Stack<markOop>          _preserved_mark_stack; // List of marks to be restored after failed promotion

   static Stack<oop>              _preserved_oop_stack;  // List of oops that need their mark restored.

   static CollectorCounters*      _counters;         // collector performance counters

   static bool                    _promotion_failed;

   static void clean_up_failed_promotion();

   static bool should_attempt_scavenge();

   static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }

   static inline void save_to_space_top_before_gc();

   // Private accessors

   static CardTableExtension* const card_table()       { assert(_card_table != NULL, "Sanity"); return _card_table; }

  public:

   // Accessors

   static int              tenuring_threshold()  { return _tenuring_threshold; }

   static elapsedTimer*    accumulated_time()    { return &_accumulated_time; }

   static bool             promotion_failed()    { return _promotion_failed; }

   static int              consecutive_skipped_scavenges()

     { return _consecutive_skipped_scavenges; }

   // Performance Counters

   static CollectorCounters* counters()           { return _counters; }

   // Used by scavenge_contents && psMarkSweep

   static ReferenceProcessor* const reference_processor() {

     assert(_ref_processor != NULL, "Sanity");

     return _ref_processor;

   }

   // Used to add tasks

   static GCTaskManager* const gc_task_manager();

   // The promotion managers tell us if they encountered overflow

   static void set_survivor_overflow(bool state) {

     _survivor_overflow = state;

   }

   // Adaptive size policy support.  When the young generation/old generation

   // boundary moves, _young_generation_boundary must be reset

   static void set_young_generation_boundary(HeapWord* v) {

     _young_generation_boundary = v;

   }

   // Called by parallelScavengeHeap to init the tenuring threshold

   static void initialize();

   // Scavenge entry point

   static void invoke();

   // Return true is a collection was done.  Return

   // false if the collection was skipped.

   static bool invoke_no_policy();

   // If an attempt to promote fails, this method is invoked

   static void oop_promotion_failed(oop obj, markOop obj_mark);

   template <class T> static inline bool should_scavenge(T* p);

   // These call should_scavenge() above and, if it returns true, also check that

   // the object was not newly copied into to_space.  The version with the bool

   // argument is a convenience wrapper that fetches the to_space pointer from

   // the heap and calls the other version (if the arg is true).

   template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);

   template <class T> static inline bool should_scavenge(T* p, bool check_to_space);

   template <class T> inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, T* p);

   // Is an object in the young generation

   // This assumes that the HeapWord argument is in the heap,

   // so it only checks one side of the complete predicate.

   inline static bool is_obj_in_young(HeapWord* o) {

     const bool result = (o >= _young_generation_boundary);

     return result;

   }

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_HPP