/*

 * Copyright 2001-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

class ChunkArray;

class ParScanWithoutBarrierClosure;

class ParScanWithBarrierClosure;

class ParRootScanWithoutBarrierClosure;

class ParRootScanWithBarrierTwoGensClosure;

class ParEvacuateFollowersClosure;

// It would be better if these types could be kept local to the .cpp file,

// but they must be here to allow ParScanClosure::do_oop_work to be defined

// in genOopClosures.inline.hpp.

typedef OopTaskQueue    ObjToScanQueue;

typedef OopTaskQueueSet ObjToScanQueueSet;

// Enable this to get push/pop/steal stats.

const int PAR_STATS_ENABLED = 0;

class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {

 private:

  ParScanWeakRefClosure* _par_cl;

 protected:

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

 public:

  ParKeepAliveClosure(ParScanWeakRefClosure* cl);

  virtual void do_oop(oop* p);

  virtual void do_oop(narrowOop* p);

};

// The state needed by thread performing parallel young-gen collection.

class ParScanThreadState {

  friend class ParScanThreadStateSet;

 private:

  ObjToScanQueue *_work_queue;

  ParGCAllocBuffer _to_space_alloc_buffer;

  ParScanWithoutBarrierClosure         _to_space_closure; // scan_without_gc_barrier

  ParScanWithBarrierClosure            _old_gen_closure; // scan_with_gc_barrier

  ParRootScanWithoutBarrierClosure     _to_space_root_closure; // scan_root_without_gc_barrier

  // One of these two will be passed to process_strong_roots, which will

  // set its generation.  The first is for two-gen configs where the

  // old gen collects the perm gen; the second is for arbitrary configs.

  // The second isn't used right now (it used to be used for the train, an

  // incremental collector) but the declaration has been left as a reminder.

  ParRootScanWithBarrierTwoGensClosure _older_gen_closure;

  // This closure will always be bound to the old gen; it will be used

  // in evacuate_followers.

  ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier

  ParEvacuateFollowersClosure          _evacuate_followers;

  DefNewGeneration::IsAliveClosure     _is_alive_closure;

  ParScanWeakRefClosure                _scan_weak_ref_closure;

  ParKeepAliveClosure                  _keep_alive_closure;

  Space* _to_space;

  Space* to_space() { return _to_space; }

  Generation* _old_gen;

  Generation* old_gen() { return _old_gen; }

  HeapWord *_young_old_boundary;

  int _hash_seed;

  int _thread_num;

  ageTable _ageTable;

  bool _to_space_full;

  int _pushes, _pops, _steals, _steal_attempts, _term_attempts;

  int _overflow_pushes, _overflow_refills, _overflow_refill_objs;

  // Timing numbers.

  double _start;

  double _start_strong_roots;

  double _strong_roots_time;

  double _start_term;

  double _term_time;

  // Helper for trim_queues. Scans subset of an array and makes

  // remainder available for work stealing.

  void scan_partial_array_and_push_remainder(oop obj);

  // In support of CMS' parallel rescan of survivor space.

  ChunkArray* _survivor_chunk_array;

  ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }

  void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);

  ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,

                     Generation* old_gen_, int thread_num_,

                     ObjToScanQueueSet* work_queue_set_, size_t desired_plab_sz_,

                     ParallelTaskTerminator& term_);

 public:

  ageTable* age_table() {return &_ageTable;}

  ObjToScanQueue* work_queue() { return _work_queue; }

  ParGCAllocBuffer* to_space_alloc_buffer() {

    return &_to_space_alloc_buffer;

  }

  ParEvacuateFollowersClosure&      evacuate_followers_closure() { return _evacuate_followers; }

  DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }

  ParScanWeakRefClosure&            scan_weak_ref_closure() { return _scan_weak_ref_closure; }

  ParKeepAliveClosure&              keep_alive_closure() { return _keep_alive_closure; }

  ParScanClosure&                   older_gen_closure() { return _older_gen_closure; }

  ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };

  // Decrease queue size below "max_size".

  void trim_queues(int max_size);

  // Is new_obj a candidate for scan_partial_array_and_push_remainder method.

  inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;

  int* hash_seed()  { return &_hash_seed; }

  int  thread_num() { return _thread_num; }

  // Allocate a to-space block of size "sz", or else return NULL.

  HeapWord* alloc_in_to_space_slow(size_t word_sz);

  HeapWord* alloc_in_to_space(size_t word_sz) {

    HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz);

    if (obj != NULL) return obj;

    else return alloc_in_to_space_slow(word_sz);

  }

  HeapWord* young_old_boundary() { return _young_old_boundary; }

  void set_young_old_boundary(HeapWord *boundary) {

    _young_old_boundary = boundary;

  }

  // Undo the most recent allocation ("obj", of "word_sz").

  void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);

  int pushes() { return _pushes; }

  int pops()   { return _pops; }

  int steals() { return _steals; }

  int steal_attempts() { return _steal_attempts; }

  int term_attempts()  { return _term_attempts; }

  int overflow_pushes() { return _overflow_pushes; }

  int overflow_refills() { return _overflow_refills; }

  int overflow_refill_objs() { return _overflow_refill_objs; }

  void note_push()  { if (PAR_STATS_ENABLED) _pushes++; }

  void note_pop()   { if (PAR_STATS_ENABLED) _pops++; }

  void note_steal() { if (PAR_STATS_ENABLED) _steals++; }

  void note_steal_attempt() { if (PAR_STATS_ENABLED) _steal_attempts++; }

  void note_term_attempt()  { if (PAR_STATS_ENABLED) _term_attempts++; }

  void note_overflow_push() { if (PAR_STATS_ENABLED) _overflow_pushes++; }

  void note_overflow_refill(int objs) {

    if (PAR_STATS_ENABLED) {

      _overflow_refills++;

      _overflow_refill_objs += objs;

    }

  }

  void start_strong_roots() {

    _start_strong_roots = os::elapsedTime();

  }

  void end_strong_roots() {

    _strong_roots_time += (os::elapsedTime() - _start_strong_roots);

  }

  double strong_roots_time() { return _strong_roots_time; }

  void start_term_time() {

    note_term_attempt();

    _start_term = os::elapsedTime();

  }

  void end_term_time() {

    _term_time += (os::elapsedTime() - _start_term);

  }

  double term_time() { return _term_time; }

  double elapsed() {

    return os::elapsedTime() - _start;

  }

};

class ParNewGenTask: public AbstractGangTask {

 private:

  ParNewGeneration*            _gen;

  Generation*                  _next_gen;

  HeapWord*                    _young_old_boundary;

  class ParScanThreadStateSet* _state_set;

public:

  ParNewGenTask(ParNewGeneration*      gen,

                Generation*            next_gen,

                HeapWord*              young_old_boundary,

                ParScanThreadStateSet* state_set);

  HeapWord* young_old_boundary() { return _young_old_boundary; }

  void work(int i);

};

class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {

 protected:

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

 public:

  KeepAliveClosure(ScanWeakRefClosure* cl);

  virtual void do_oop(oop* p);

  virtual void do_oop(narrowOop* p);

};

class EvacuateFollowersClosureGeneral: public VoidClosure {

 private:

  GenCollectedHeap* _gch;

  int               _level;

  OopsInGenClosure* _scan_cur_or_nonheap;

  OopsInGenClosure* _scan_older;

 public:

  EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,

                                  OopsInGenClosure* cur,

                                  OopsInGenClosure* older);

  virtual void do_void();

};

// Closure for scanning ParNewGeneration.

// Same as ScanClosure, except does parallel GC barrier.

class ScanClosureWithParBarrier: public ScanClosure {

 protected:

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

 public:

  ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);

  virtual void do_oop(oop* p);

  virtual void do_oop(narrowOop* p);

};

// Implements AbstractRefProcTaskExecutor for ParNew.

class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {

 private:

  ParNewGeneration&      _generation;

  ParScanThreadStateSet& _state_set;

 public:

  ParNewRefProcTaskExecutor(ParNewGeneration& generation,

                            ParScanThreadStateSet& state_set)

    : _generation(generation), _state_set(state_set)

  { }

  // Executes a task using worker threads.

  virtual void execute(ProcessTask& task);

  virtual void execute(EnqueueTask& task);

  // Switch to single threaded mode.

  virtual void set_single_threaded_mode();

};

// A Generation that does parallel young-gen collection.

class ParNewGeneration: public DefNewGeneration {

  friend class ParNewGenTask;

  friend class ParNewRefProcTask;

  friend class ParNewRefProcTaskExecutor;

  friend class ParScanThreadStateSet;

 private:

  // XXX use a global constant instead of 64!

  struct ObjToScanQueuePadded {

        ObjToScanQueue work_queue;

        char pad[64 - sizeof(ObjToScanQueue)];  // prevent false sharing

  };

  // The per-thread work queues, available here for stealing.

  ObjToScanQueueSet* _task_queues;

  // Desired size of survivor space plab's

  PLABStats _plab_stats;

  // A list of from-space images of to-be-scanned objects, threaded through

  // klass-pointers (klass information already copied to the forwarded

  // image.)  Manipulated with CAS.

  oop _overflow_list;

  // If true, older generation does not support promotion undo, so avoid.

  static bool _avoid_promotion_undo;

  // This closure is used by the reference processor to filter out

  // references to live referent.

  DefNewGeneration::IsAliveClosure _is_alive_closure;

  static oop real_forwardee_slow(oop obj);

  static void waste_some_time();

  // Preserve the mark of "obj", if necessary, in preparation for its mark

  // word being overwritten with a self-forwarding-pointer.

  void preserve_mark_if_necessary(oop obj, markOop m);

 protected:

  bool _survivor_overflow;

  bool avoid_promotion_undo() { return _avoid_promotion_undo; }

  void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; }

  bool survivor_overflow() { return _survivor_overflow; }

  void set_survivor_overflow(bool v) { _survivor_overflow = v; }

  // Adjust the tenuring threshold.  See the implementation for

  // the details of the policy.

  virtual void adjust_desired_tenuring_threshold();

 public:

  ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);

  ~ParNewGeneration() {

    for (uint i = 0; i < ParallelGCThreads; i++)

        delete _task_queues->queue(i);

    delete _task_queues;

  }

  virtual void ref_processor_init();

  virtual Generation::Name kind()        { return Generation::ParNew; }

  virtual const char* name() const;

  virtual const char* short_name() const { return "ParNew"; }

  // override

  virtual bool refs_discovery_is_mt()     const {

    assert(UseParNewGC, "ParNewGeneration only when UseParNewGC");

    return ParallelGCThreads > 1;

  }

  // Make the collection virtual.

  virtual void collect(bool   full,

                       bool   clear_all_soft_refs,

                       size_t size,

                       bool   is_tlab);

  // This needs to be visible to the closure function.

  // "obj" is the object to be copied, "m" is a recent value of its mark

  // that must not contain a forwarding pointer (though one might be

  // inserted in "obj"s mark word by a parallel thread).

  inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state,

                             oop obj, size_t obj_sz, markOop m) {

    if (_avoid_promotion_undo) {

       return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state,

                                                             obj, obj_sz, m);

    }

    return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m);

  }

  oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state,

                             oop obj, size_t obj_sz, markOop m);

  oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state,

                             oop obj, size_t obj_sz, markOop m);

  // Push the given (from-space) object on the global overflow list.

  void push_on_overflow_list(oop from_space_obj);

  // If the global overflow list is non-empty, move some tasks from it

  // onto "work_q" (which must be empty).  No more than 1/4 of the

  // max_elems of "work_q" are moved.

  bool take_from_overflow_list(ParScanThreadState* par_scan_state);

  // The task queues to be used by parallel GC threads.

  ObjToScanQueueSet* task_queues() {

    return _task_queues;

  }

  PLABStats* plab_stats() {

    return &_plab_stats;

  }

  size_t desired_plab_sz() {

    return _plab_stats.desired_plab_sz();

  }

  static oop real_forwardee(oop obj);

  DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);)

};