/*

 * 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

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 */

#include "gc/parallel/psCardTable.hpp"

#include "gc/parallel/psVirtualspace.hpp"

#include "gc/shared/collectorCounters.hpp"

#include "gc/shared/gcTrace.hpp"

#include "memory/allocation.hpp"

#include "oops/oop.hpp"

#include "utilities/stack.hpp"

class GCTaskManager;

class GCTaskQueue;

class OopStack;

class ReferenceProcessor;

class ParallelScavengeHeap;

class ParallelScavengeTracer;

class PSIsAliveClosure;

class PSRefProcTaskExecutor;

class STWGCTimer;

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 SpanSubjectToDiscoveryClosure _span_based_discoverer;

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

  static PSIsAliveClosure              _is_alive_closure;     // Closure used for reference processing

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

  static bool                          _survivor_overflow;    // Overflow this collection

  static uint                          _tenuring_threshold;   // tenuring threshold for next scavenge

  static elapsedTimer                  _accumulated_time;     // total time spent on scavenge

  static STWGCTimer                    _gc_timer;             // GC time book keeper

  static ParallelScavengeTracer        _gc_tracer;          // GC tracing

  // 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 HeapWord*            _young_generation_boundary;

  // Used to optimize compressed oops young gen boundary checking.

  static uintptr_t            _young_generation_boundary_compressed;

  static CollectorCounters*   _counters;             // collector performance counters

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

  static const ParallelScavengeTracer* gc_tracer() { return &_gc_tracer; }

 public:

  // Accessors

  static uint             tenuring_threshold()  { return _tenuring_threshold; }

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

  static int              consecutive_skipped_scavenges()

    { return _consecutive_skipped_scavenges; }

  // Performance Counters

  static CollectorCounters* counters()           { return _counters; }

  static void set_subject_to_discovery_span(MemRegion mr) {

    _span_based_discoverer.set_span(mr);

  }

  // 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);

  // Called by parallelScavengeHeap to init the tenuring threshold

  static void initialize();

  // Scavenge entry point.  This may invoke a full gc; return true if so.

  static bool invoke();

  // Return true if a collection was done; false otherwise.

  static bool invoke_no_policy();

  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);

  static void copy_and_push_safe_barrier_from_klass(PSPromotionManager* pm, oop* p);

  // Is an object in the young generation

  // This assumes that the 'o' is in the heap,

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

  inline static bool is_obj_in_young(oop o) {

    return (HeapWord*)o >= _young_generation_boundary;

  }

  inline static bool is_obj_in_young(narrowOop o) {

    return (uintptr_t)o >= _young_generation_boundary_compressed;

  }

  inline static bool is_obj_in_young(HeapWord* o) {

    return o >= _young_generation_boundary;

  }

};