/*

 * 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

 * questions.

 *

 */

#include "gc/cms/freeChunk.hpp"

// Forward declarations

class CompactibleFreeListSpace;

class PromotedObject {

 private:

  enum {

    promoted_mask  = right_n_bits(2),   // i.e. 0x3

    displaced_mark = nth_bit(2),        // i.e. 0x4

    next_mask      = ~(right_n_bits(3)) // i.e. ~(0x7)

  };

  // Below, we want _narrow_next in the "higher" 32 bit slot,

  // whose position will depend on endian-ness of the platform.

  // This is so that there is no interference with the

  // cms_free_bit occupying bit position 7 (lsb == 0)

  // when we are using compressed oops; see FreeChunk::is_free().

  // We cannot move the cms_free_bit down because currently

  // biased locking code assumes that age bits are contiguous

  // with the lock bits. Even if that assumption were relaxed,

  // the least position we could move this bit to would be

  // to bit position 3, which would require 16 byte alignment.

  typedef struct {

#ifdef VM_LITTLE_ENDIAN

    LP64_ONLY(narrowOop _pad;)

              narrowOop _narrow_next;

#else

              narrowOop _narrow_next;

    LP64_ONLY(narrowOop _pad;)

#endif

  } Data;

  union {

    intptr_t _next;

    Data     _data;

  };

 public:

  PromotedObject* next() const;

  void setNext(PromotedObject* x);

  inline void setPromotedMark() {

    _next |= promoted_mask;

    assert(!((FreeChunk*)this)->is_free(), "Error");

  }

  inline bool hasPromotedMark() const {

    assert(!((FreeChunk*)this)->is_free(), "Error");

    return (_next & promoted_mask) == promoted_mask;

  }

  inline void setDisplacedMark() {

    _next |= displaced_mark;

    assert(!((FreeChunk*)this)->is_free(), "Error");

  }

  inline bool hasDisplacedMark() const {

    assert(!((FreeChunk*)this)->is_free(), "Error");

    return (_next & displaced_mark) != 0;

  }

  inline void clear_next()        {

    _next = 0;

    assert(!((FreeChunk*)this)->is_free(), "Error");

  }

  debug_only(void *next_addr() { return (void *) &_next; })

};

class SpoolBlock: public FreeChunk {

  friend class PromotionInfo;

 protected:

  SpoolBlock*  nextSpoolBlock;

  size_t       bufferSize;        // number of usable words in this block

  markOop*     displacedHdr;      // the displaced headers start here

  // Note about bufferSize: it denotes the number of entries available plus 1;

  // legal indices range from 1 through BufferSize - 1.  See the verification

  // code verify() that counts the number of displaced headers spooled.

  size_t computeBufferSize() {

    return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);

  }

 public:

  void init() {

    bufferSize = computeBufferSize();

    displacedHdr = (markOop*)&displacedHdr;

    nextSpoolBlock = NULL;

  }

  void print_on(outputStream* st) const;

  void print() const { print_on(tty); }

};

class PromotionInfo {

  bool            _tracking;      // set if tracking

  CompactibleFreeListSpace* _space; // the space to which this belongs

  PromotedObject* _promoHead;     // head of list of promoted objects

  PromotedObject* _promoTail;     // tail of list of promoted objects

  SpoolBlock*     _spoolHead;     // first spooling block

  SpoolBlock*     _spoolTail;     // last  non-full spooling block or null

  SpoolBlock*     _splice_point;  // when _spoolTail is null, holds list tail

  SpoolBlock*     _spareSpool;    // free spool buffer

  size_t          _firstIndex;    // first active index in

                                  // first spooling block (_spoolHead)

  size_t          _nextIndex;     // last active index + 1 in last

                                  // spooling block (_spoolTail)

 private:

  // ensure that spooling space exists; return true if there is spooling space

  bool ensure_spooling_space_work();

 public:

  PromotionInfo() :

    _tracking(0), _space(NULL),

    _promoHead(NULL), _promoTail(NULL),

    _spoolHead(NULL), _spoolTail(NULL),

    _spareSpool(NULL), _firstIndex(1),

    _nextIndex(1) {}

  bool noPromotions() const {

    assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");

    return _promoHead == NULL;

  }

  void startTrackingPromotions();

  void stopTrackingPromotions();

  bool tracking() const          { return _tracking;  }

  void track(PromotedObject* trackOop);      // keep track of a promoted oop

  // The following variant must be used when trackOop is not fully

  // initialized and has a NULL klass:

  void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop

  void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }

  CompactibleFreeListSpace* space() const     { return _space; }

  markOop nextDisplacedHeader(); // get next header & forward spool pointer

  void    saveDisplacedHeader(markOop hdr);

                                 // save header and forward spool

  inline size_t refillSize() const;

  SpoolBlock* getSpoolBlock();   // return a free spooling block

  inline bool has_spooling_space() {

    return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;

  }

  // ensure that spooling space exists

  bool ensure_spooling_space() {

    return has_spooling_space() || ensure_spooling_space_work();

  }

  template <typename OopClosureType>

  void promoted_oops_iterate(OopClosureType* cl);

  void verify()  const;

  void reset() {

    _promoHead = NULL;

    _promoTail = NULL;

    _spoolHead = NULL;

    _spoolTail = NULL;

    _spareSpool = NULL;

    _firstIndex = 0;

    _nextIndex = 0;

  }

  void print_on(outputStream* st) const;

};