/*

 * Copyright 2001-2006 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.

 *

 */

// Classes in support of keeping track of promotions into a non-Contiguous

// space, in this case a CompactibleFreeListSpace.

#define CFLS_LAB_REFILL_STATS 0

// Forward declarations

class CompactibleFreeListSpace;

class BlkClosure;

class BlkClosureCareful;

class UpwardsObjectClosure;

class ObjectClosureCareful;

class Klass;

class PromotedObject VALUE_OBJ_CLASS_SPEC {

 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)

  };

  intptr_t _next;

 public:

  inline PromotedObject* next() const {

    return (PromotedObject*)(_next & next_mask);

  }

  inline void setNext(PromotedObject* x) {

    assert(((intptr_t)x & ~next_mask) == 0,

           "Conflict in bit usage, "

           " or insufficient alignment of objects");

    _next |= (intptr_t)x;

  }

  inline void setPromotedMark() {

    _next |= promoted_mask;

  }

  inline bool hasPromotedMark() const {

    return (_next & promoted_mask) == promoted_mask;

  }

  inline void setDisplacedMark() {

    _next |= displaced_mark;

  }

  inline bool hasDisplacedMark() const {

    return (_next & displaced_mark) != 0;

  }

  inline void clearNext()        { _next = 0; }

  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;

  }

};

class PromotionInfo VALUE_OBJ_CLASS_SPEC {

  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, klassOop 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();

  }

  #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix)  \

    void promoted_oops_iterate##nv_suffix(OopClosureType* cl);

  ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)

  #undef PROMOTED_OOPS_ITERATE_DECL

  void promoted_oops_iterate(OopsInGenClosure* cl) {

    promoted_oops_iterate_v(cl);

  }

  void verify()  const;

  void reset() {

    _promoHead = NULL;

    _promoTail = NULL;

    _spoolHead = NULL;

    _spoolTail = NULL;

    _spareSpool = NULL;

    _firstIndex = 0;

    _nextIndex = 0;

  }

};

class LinearAllocBlock VALUE_OBJ_CLASS_SPEC {

 public:

  LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0),

    _allocation_size_limit(0) {}

  void set(HeapWord* ptr, size_t word_size, size_t refill_size,

    size_t allocation_size_limit) {

    _ptr = ptr;

    _word_size = word_size;

    _refillSize = refill_size;

    _allocation_size_limit = allocation_size_limit;

  }

  HeapWord* _ptr;

  size_t    _word_size;

  size_t    _refillSize;

  size_t    _allocation_size_limit;  // largest size that will be allocated

};

// Concrete subclass of CompactibleSpace that implements

// a free list space, such as used in the concurrent mark sweep

// generation.

class CompactibleFreeListSpace: public CompactibleSpace {

  friend class VMStructs;

  friend class ConcurrentMarkSweepGeneration;

  friend class ASConcurrentMarkSweepGeneration;

  friend class CMSCollector;

  friend class CMSPermGenGen;

  // Local alloc buffer for promotion into this space.

  friend class CFLS_LAB;

  // "Size" of chunks of work (executed during parallel remark phases

  // of CMS collection); this probably belongs in CMSCollector, although

  // it's cached here because it's used in

  // initialize_sequential_subtasks_for_rescan() which modifies

  // par_seq_tasks which also lives in Space. XXX

  const size_t _rescan_task_size;

  const size_t _marking_task_size;

  // Yet another sequential tasks done structure. This supports

  // CMS GC, where we have threads dynamically

  // claiming sub-tasks from a larger parallel task.

  SequentialSubTasksDone _conc_par_seq_tasks;

  BlockOffsetArrayNonContigSpace _bt;

  CMSCollector* _collector;

  ConcurrentMarkSweepGeneration* _gen;

  // Data structures for free blocks (used during allocation/sweeping)

  // Allocation is done linearly from two different blocks depending on

  // whether the request is small or large, in an effort to reduce

  // fragmentation. We assume that any locking for allocation is done

  // by the containing generation. Thus, none of the methods in this

  // space are re-entrant.

  enum SomeConstants {

    SmallForLinearAlloc = 16,        // size < this then use _sLAB

    SmallForDictionary  = 257,       // size < this then use _indexedFreeList

    IndexSetSize        = SmallForDictionary,  // keep this odd-sized

    IndexSetStart       = MinObjAlignment,

    IndexSetStride      = MinObjAlignment

  };

 private:

  enum FitStrategyOptions {

    FreeBlockStrategyNone = 0,

    FreeBlockBestFitFirst

  };

  PromotionInfo _promoInfo;

  // helps to impose a global total order on freelistLock ranks;

  // assumes that CFLSpace's are allocated in global total order

  static int   _lockRank;

  // a lock protecting the free lists and free blocks;

  // mutable because of ubiquity of locking even for otherwise const methods

  mutable Mutex _freelistLock;

  // locking verifier convenience function

  void assert_locked() const PRODUCT_RETURN;

  // Linear allocation blocks

  LinearAllocBlock _smallLinearAllocBlock;

  FreeBlockDictionary::DictionaryChoice _dictionaryChoice;

  FreeBlockDictionary* _dictionary;    // ptr to dictionary for large size blocks

  FreeList _indexedFreeList[IndexSetSize];

                                       // indexed array for small size blocks

  // allocation stategy

  bool       _fitStrategy;      // Use best fit strategy.

  bool       _adaptive_freelists; // Use adaptive freelists

  // This is an address close to the largest free chunk in the heap.

  // It is currently assumed to be at the end of the heap.  Free

  // chunks with addresses greater than nearLargestChunk are coalesced

  // in an effort to maintain a large chunk at the end of the heap.

  HeapWord*  _nearLargestChunk;

  // Used to keep track of limit of sweep for the space

  HeapWord* _sweep_limit;

  // Support for compacting cms

  HeapWord* cross_threshold(HeapWord* start, HeapWord* end);

  HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top);

  // Initialization helpers.

  void initializeIndexedFreeListArray();

  // Extra stuff to manage promotion parallelism.

  // a lock protecting the dictionary during par promotion allocation.

  mutable Mutex _parDictionaryAllocLock;

  Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; }

  // Locks protecting the exact lists during par promotion allocation.

  Mutex* _indexedFreeListParLocks[IndexSetSize];

#if CFLS_LAB_REFILL_STATS

  // Some statistics.

  jint  _par_get_chunk_from_small;

  jint  _par_get_chunk_from_large;

#endif

  // Attempt to obtain up to "n" blocks of the size "word_sz" (which is

  // required to be smaller than "IndexSetSize".)  If successful,

  // adds them to "fl", which is required to be an empty free list.

  // If the count of "fl" is negative, it's absolute value indicates a

  // number of free chunks that had been previously "borrowed" from global

  // list of size "word_sz", and must now be decremented.

  void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl);

  // Allocation helper functions

  // Allocate using a strategy that takes from the indexed free lists

  // first.  This allocation strategy assumes a companion sweeping

  // strategy that attempts to keep the needed number of chunks in each

  // indexed free lists.

  HeapWord* allocate_adaptive_freelists(size_t size);

  // Allocate from the linear allocation buffers first.  This allocation

  // strategy assumes maximal coalescing can maintain chunks large enough

  // to be used as linear allocation buffers.

  HeapWord* allocate_non_adaptive_freelists(size_t size);

  // Gets a chunk from the linear allocation block (LinAB).  If there

  // is not enough space in the LinAB, refills it.

  HeapWord*  getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size);

  HeapWord*  getChunkFromSmallLinearAllocBlock(size_t size);

  // Get a chunk from the space remaining in the linear allocation block.  Do

  // not attempt to refill if the space is not available, return NULL.  Do the

  // repairs on the linear allocation block as appropriate.

  HeapWord*  getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size);

  inline HeapWord*  getChunkFromSmallLinearAllocBlockRemainder(size_t size);

  // Helper function for getChunkFromIndexedFreeList.

  // Replenish the indexed free list for this "size".  Do not take from an

  // underpopulated size.

  FreeChunk*  getChunkFromIndexedFreeListHelper(size_t size);

  // Get a chunk from the indexed free list.  If the indexed free list

  // does not have a free chunk, try to replenish the indexed free list

  // then get the free chunk from the replenished indexed free list.

  inline FreeChunk* getChunkFromIndexedFreeList(size_t size);

  // The returned chunk may be larger than requested (or null).

  FreeChunk* getChunkFromDictionary(size_t size);

  // The returned chunk is the exact size requested (or null).

  FreeChunk* getChunkFromDictionaryExact(size_t size);

  // Find a chunk in the indexed free list that is the best

  // fit for size "numWords".

  FreeChunk* bestFitSmall(size_t numWords);

  // For free list "fl" of chunks of size > numWords,

  // remove a chunk, split off a chunk of size numWords

  // and return it.  The split off remainder is returned to

  // the free lists.  The old name for getFromListGreater

  // was lookInListGreater.

  FreeChunk* getFromListGreater(FreeList* fl, size_t numWords);

  // Get a chunk in the indexed free list or dictionary,

  // by considering a larger chunk and splitting it.

  FreeChunk* getChunkFromGreater(size_t numWords);

  //  Verify that the given chunk is in the indexed free lists.

  bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const;

  // Remove the specified chunk from the indexed free lists.

  void       removeChunkFromIndexedFreeList(FreeChunk* fc);

  // Remove the specified chunk from the dictionary.

  void       removeChunkFromDictionary(FreeChunk* fc);

  // Split a free chunk into a smaller free chunk of size "new_size".

  // Return the smaller free chunk and return the remainder to the

  // free lists.

  FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size);

  // Add a chunk to the free lists.

  void       addChunkToFreeLists(HeapWord* chunk, size_t size);

  // Add a chunk to the free lists, preferring to suffix it

  // to the last free chunk at end of space if possible, and

  // updating the block census stats as well as block offset table.

  // Take any locks as appropriate if we are multithreaded.

  void       addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size);

  // Add a free chunk to the indexed free lists.

  void       returnChunkToFreeList(FreeChunk* chunk);

  // Add a free chunk to the dictionary.

  void       returnChunkToDictionary(FreeChunk* chunk);

  // Functions for maintaining the linear allocation buffers (LinAB).

  // Repairing a linear allocation block refers to operations

  // performed on the remainder of a LinAB after an allocation

  // has been made from it.

  void       repairLinearAllocationBlocks();

  void       repairLinearAllocBlock(LinearAllocBlock* blk);

  void       refillLinearAllocBlock(LinearAllocBlock* blk);

  void       refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk);

  void       refillLinearAllocBlocksIfNeeded();

  void       verify_objects_initialized() const;

  // Statistics reporting helper functions

  void       reportFreeListStatistics() const;

  void       reportIndexedFreeListStatistics() const;

  size_t     maxChunkSizeInIndexedFreeLists() const;

  size_t     numFreeBlocksInIndexedFreeLists() const;

  // Accessor

  HeapWord* unallocated_block() const {

    HeapWord* ub = _bt.unallocated_block();

    assert(ub >= bottom() &&

           ub <= end(), "space invariant");

    return ub;

  }

  void freed(HeapWord* start, size_t size) {

    _bt.freed(start, size);

  }

 protected:

  // reset the indexed free list to its initial empty condition.

  void resetIndexedFreeListArray();

  // reset to an initial state with a single free block described

  // by the MemRegion parameter.

  void reset(MemRegion mr);

  // Return the total number of words in the indexed free lists.

  size_t     totalSizeInIndexedFreeLists() const;

 public:

  // Constructor...

  CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr,

                           bool use_adaptive_freelists,

                           FreeBlockDictionary::DictionaryChoice);

  // accessors

  bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; }

  FreeBlockDictionary* dictionary() const { return _dictionary; }

  HeapWord* nearLargestChunk() const { return _nearLargestChunk; }

  void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; }

  // Return the free chunk at the end of the space.  If no such

  // chunk exists, return NULL.

  FreeChunk* find_chunk_at_end();

  bool adaptive_freelists() { return _adaptive_freelists; }

  void set_collector(CMSCollector* collector) { _collector = collector; }

  // Support for parallelization of rescan and marking

  const size_t rescan_task_size()  const { return _rescan_task_size;  }

  const size_t marking_task_size() const { return _marking_task_size; }

  SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; }

  void initialize_sequential_subtasks_for_rescan(int n_threads);

  void initialize_sequential_subtasks_for_marking(int n_threads,

         HeapWord* low = NULL);

#if CFLS_LAB_REFILL_STATS

  void print_par_alloc_stats();

#endif

  // Space enquiries

  size_t used() const;

  size_t free() const;

  size_t max_alloc_in_words() const;

  // XXX: should have a less conservative used_region() than that of

  // Space; we could consider keeping track of highest allocated

  // address and correcting that at each sweep, as the sweeper

  // goes through the entire allocated part of the generation. We

  // could also use that information to keep the sweeper from

  // sweeping more than is necessary. The allocator and sweeper will

  // of course need to synchronize on this, since the sweeper will

  // try to bump down the address and the allocator will try to bump it up.

  // For now, however, we'll just use the default used_region()

  // which overestimates the region by returning the entire

  // committed region (this is safe, but inefficient).

  // Returns a subregion of the space containing all the objects in

  // the space.

  MemRegion used_region() const {

    return MemRegion(bottom(),

                     BlockOffsetArrayUseUnallocatedBlock ?

                     unallocated_block() : end());

  }

  // This is needed because the default implementation uses block_start()

  // which can;t be used at certain times (for example phase 3 of mark-sweep).

  // A better fix is to change the assertions in phase 3 of mark-sweep to

  // use is_in_reserved(), but that is deferred since the is_in() assertions

  // are buried through several layers of callers and are used elsewhere

  // as well.

  bool is_in(const void* p) const {

    return used_region().contains(p);

  }

  virtual bool is_free_block(const HeapWord* p) const;

  // Resizing support

  void set_end(HeapWord* value);  // override

  // mutual exclusion support

  Mutex* freelistLock() const { return &_freelistLock; }

  // Iteration support

  void oop_iterate(MemRegion mr, OopClosure* cl);

  void oop_iterate(OopClosure* cl);

  void object_iterate(ObjectClosure* blk);

  void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);

  // Requires that "mr" be entirely within the space.

  // Apply "cl->do_object" to all objects that intersect with "mr".

  // If the iteration encounters an unparseable portion of the region,

  // terminate the iteration and return the address of the start of the

  // subregion that isn't done.  Return of "NULL" indicates that the

  // interation completed.

  virtual HeapWord*

       object_iterate_careful_m(MemRegion mr,

                                ObjectClosureCareful* cl);

  virtual HeapWord*

       object_iterate_careful(ObjectClosureCareful* cl);

  // Override: provides a DCTO_CL specific to this kind of space.

  DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl,

                                     CardTableModRefBS::PrecisionStyle precision,

                                     HeapWord* boundary);

  void blk_iterate(BlkClosure* cl);

  void blk_iterate_careful(BlkClosureCareful* cl);

  HeapWord* block_start(const void* p) const;

  HeapWord* block_start_careful(const void* p) const;

  size_t block_size(const HeapWord* p) const;

  size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const;

  bool block_is_obj(const HeapWord* p) const;

  bool obj_is_alive(const HeapWord* p) const;

  size_t block_size_nopar(const HeapWord* p) const;

  bool block_is_obj_nopar(const HeapWord* p) const;

  // iteration support for promotion

  void save_marks();

  bool no_allocs_since_save_marks();

  void object_iterate_since_last_GC(ObjectClosure* cl);

  // iteration support for sweeping

  void save_sweep_limit() {

    _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ?

                   unallocated_block() : end();

  }

  NOT_PRODUCT(

    void clear_sweep_limit() { _sweep_limit = NULL; }

  )

  HeapWord* sweep_limit() { return _sweep_limit; }

  // Apply "blk->do_oop" to the addresses of all reference fields in objects