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

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 * accompanied this code).

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 * 2 along with this work; if not, write to the Free Software Foundation,

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP

#include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"

#include "gc_implementation/g1/g1_specialized_oop_closures.hpp"

#include "gc_implementation/g1/survRateGroup.hpp"

#include "gc_implementation/shared/ageTable.hpp"

#include "gc_implementation/shared/spaceDecorator.hpp"

#include "memory/space.inline.hpp"

#include "memory/watermark.hpp"

#ifndef SERIALGC

// A HeapRegion is the smallest piece of a G1CollectedHeap that

// can be collected independently.

// NOTE: Although a HeapRegion is a Space, its

// Space::initDirtyCardClosure method must not be called.

// The problem is that the existence of this method breaks

// the independence of barrier sets from remembered sets.

// The solution is to remove this method from the definition

// of a Space.

class CompactibleSpace;

class ContiguousSpace;

class HeapRegionRemSet;

class HeapRegionRemSetIterator;

class HeapRegion;

// A dirty card to oop closure for heap regions. It

// knows how to get the G1 heap and how to use the bitmap

// in the concurrent marker used by G1 to filter remembered

// sets.

class HeapRegionDCTOC : public ContiguousSpaceDCTOC {

public:

  // Specification of possible DirtyCardToOopClosure filtering.

  enum FilterKind {

    NoFilterKind,

    IntoCSFilterKind,

    OutOfRegionFilterKind

  };

protected:

  HeapRegion* _hr;

  FilterKind _fk;

  G1CollectedHeap* _g1;

  void walk_mem_region_with_cl(MemRegion mr,

                               HeapWord* bottom, HeapWord* top,

                               OopClosure* cl);

  // We don't specialize this for FilteringClosure; filtering is handled by

  // the "FilterKind" mechanism.  But we provide this to avoid a compiler

  // warning.

  void walk_mem_region_with_cl(MemRegion mr,

                               HeapWord* bottom, HeapWord* top,

                               FilteringClosure* cl) {

    HeapRegionDCTOC::walk_mem_region_with_cl(mr, bottom, top,

                                                       (OopClosure*)cl);

  }

  // Get the actual top of the area on which the closure will

  // operate, given where the top is assumed to be (the end of the

  // memory region passed to do_MemRegion) and where the object

  // at the top is assumed to start. For example, an object may

  // start at the top but actually extend past the assumed top,

  // in which case the top becomes the end of the object.

  HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) {

    return ContiguousSpaceDCTOC::get_actual_top(top, top_obj);

  }

  // Walk the given memory region from bottom to (actual) top

  // looking for objects and applying the oop closure (_cl) to

  // them. The base implementation of this treats the area as

  // blocks, where a block may or may not be an object. Sub-

  // classes should override this to provide more accurate

  // or possibly more efficient walking.

  void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) {

    Filtering_DCTOC::walk_mem_region(mr, bottom, top);

  }

public:

  HeapRegionDCTOC(G1CollectedHeap* g1,

                  HeapRegion* hr, OopClosure* cl,

                  CardTableModRefBS::PrecisionStyle precision,

                  FilterKind fk);

};

// The complicating factor is that BlockOffsetTable diverged

// significantly, and we need functionality that is only in the G1 version.

// So I copied that code, which led to an alternate G1 version of

// OffsetTableContigSpace.  If the two versions of BlockOffsetTable could

// be reconciled, then G1OffsetTableContigSpace could go away.

// The idea behind time stamps is the following. Doing a save_marks on

// all regions at every GC pause is time consuming (if I remember

// well, 10ms or so). So, we would like to do that only for regions

// that are GC alloc regions. To achieve this, we use time

// stamps. For every evacuation pause, G1CollectedHeap generates a

// unique time stamp (essentially a counter that gets

// incremented). Every time we want to call save_marks on a region,

// we set the saved_mark_word to top and also copy the current GC

// time stamp to the time stamp field of the space. Reading the

// saved_mark_word involves checking the time stamp of the

// region. If it is the same as the current GC time stamp, then we

// can safely read the saved_mark_word field, as it is valid. If the

// time stamp of the region is not the same as the current GC time

// stamp, then we instead read top, as the saved_mark_word field is

// invalid. Time stamps (on the regions and also on the

// G1CollectedHeap) are reset at every cleanup (we iterate over

// the regions anyway) and at the end of a Full GC. The current scheme

// that uses sequential unsigned ints will fail only if we have 4b

// evacuation pauses between two cleanups, which is _highly_ unlikely.

class G1OffsetTableContigSpace: public ContiguousSpace {

  friend class VMStructs;

 protected:

  G1BlockOffsetArrayContigSpace _offsets;

  Mutex _par_alloc_lock;

  volatile unsigned _gc_time_stamp;

 public:

  // Constructor.  If "is_zeroed" is true, the MemRegion "mr" may be

  // assumed to contain zeros.

  G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,

                           MemRegion mr, bool is_zeroed = false);

  void set_bottom(HeapWord* value);

  void set_end(HeapWord* value);

  virtual HeapWord* saved_mark_word() const;

  virtual void set_saved_mark();

  void reset_gc_time_stamp() { _gc_time_stamp = 0; }

  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);

  virtual void clear(bool mangle_space);

  HeapWord* block_start(const void* p);

  HeapWord* block_start_const(const void* p) const;

  // Add offset table update.

  virtual HeapWord* allocate(size_t word_size);

  HeapWord* par_allocate(size_t word_size);

  // MarkSweep support phase3

  virtual HeapWord* initialize_threshold();

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

  virtual void print() const;

  void reset_bot() {

    _offsets.zero_bottom_entry();

    _offsets.initialize_threshold();

  }

  void update_bot_for_object(HeapWord* start, size_t word_size) {

    _offsets.alloc_block(start, word_size);

  }

  void print_bot_on(outputStream* out) {

    _offsets.print_on(out);

  }

};

class HeapRegion: public G1OffsetTableContigSpace {

  friend class VMStructs;

 private:

  enum HumongousType {

    NotHumongous = 0,

    StartsHumongous,

    ContinuesHumongous

  };

  // The next filter kind that should be used for a "new_dcto_cl" call with

  // the "traditional" signature.

  HeapRegionDCTOC::FilterKind _next_fk;

  // Requires that the region "mr" be dense with objects, and begin and end

  // with an object.

  void oops_in_mr_iterate(MemRegion mr, OopClosure* cl);

  // The remembered set for this region.

  // (Might want to make this "inline" later, to avoid some alloc failure

  // issues.)

  HeapRegionRemSet* _rem_set;

  G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }

 protected:

  // If this region is a member of a HeapRegionSeq, the index in that

  // sequence, otherwise -1.

  int  _hrs_index;

  HumongousType _humongous_type;

  // For a humongous region, region in which it starts.

  HeapRegion* _humongous_start_region;

  // For the start region of a humongous sequence, it's original end().

  HeapWord* _orig_end;

  // True iff the region is in current collection_set.

  bool _in_collection_set;

  // Is this or has it been an allocation region in the current collection

  // pause.

  bool _is_gc_alloc_region;

  // True iff an attempt to evacuate an object in the region failed.

  bool _evacuation_failed;

  // A heap region may be a member one of a number of special subsets, each

  // represented as linked lists through the field below.  Currently, these

  // sets include:

  //   The collection set.

  //   The set of allocation regions used in a collection pause.

  //   Spaces that may contain gray objects.

  HeapRegion* _next_in_special_set;

  // next region in the young "generation" region set

  HeapRegion* _next_young_region;

  // Next region whose cards need cleaning

  HeapRegion* _next_dirty_cards_region;

  // For parallel heapRegion traversal.

  jint _claimed;

  // We use concurrent marking to determine the amount of live data

  // in each heap region.

  size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.

  size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.

  // See "sort_index" method.  -1 means is not in the array.

  int _sort_index;

  // <PREDICTION>

  double _gc_efficiency;

  // </PREDICTION>

  enum YoungType {

    NotYoung,                   // a region is not young

    Young,                      // a region is young

    Survivor                    // a region is young and it contains

                                // survivor

  };

  volatile YoungType _young_type;

  int  _young_index_in_cset;

  SurvRateGroup* _surv_rate_group;

  int  _age_index;

  // The start of the unmarked area. The unmarked area extends from this

  // word until the top and/or end of the region, and is the part

  // of the region for which no marking was done, i.e. objects may

  // have been allocated in this part since the last mark phase.

  // "prev" is the top at the start of the last completed marking.

  // "next" is the top at the start of the in-progress marking (if any.)

  HeapWord* _prev_top_at_mark_start;

  HeapWord* _next_top_at_mark_start;

  // If a collection pause is in progress, this is the top at the start

  // of that pause.

  // We've counted the marked bytes of objects below here.

  HeapWord* _top_at_conc_mark_count;

  void init_top_at_mark_start() {

    assert(_prev_marked_bytes == 0 &&

           _next_marked_bytes == 0,

           "Must be called after zero_marked_bytes.");

    HeapWord* bot = bottom();

    _prev_top_at_mark_start = bot;

    _next_top_at_mark_start = bot;

    _top_at_conc_mark_count = bot;

  }

  void set_young_type(YoungType new_type) {

    //assert(_young_type != new_type, "setting the same type" );

    // TODO: add more assertions here

    _young_type = new_type;

  }

  // Cached attributes used in the collection set policy information

  // The RSet length that was added to the total value

  // for the collection set.

  size_t _recorded_rs_length;

  // The predicted elapsed time that was added to total value

  // for the collection set.

  double _predicted_elapsed_time_ms;

  // The predicted number of bytes to copy that was added to

  // the total value for the collection set.

  size_t _predicted_bytes_to_copy;

 public:

  // If "is_zeroed" is "true", the region "mr" can be assumed to contain zeros.

  HeapRegion(G1BlockOffsetSharedArray* sharedOffsetArray,

             MemRegion mr, bool is_zeroed);

  static int LogOfHRGrainBytes;

  static int LogOfHRGrainWords;

  // The normal type of these should be size_t. However, they used to

  // be members of an enum before and they are assumed by the

  // compilers to be ints. To avoid going and fixing all their uses,

  // I'm declaring them as ints. I'm not anticipating heap region

  // sizes to reach anywhere near 2g, so using an int here is safe.

  static int GrainBytes;

  static int GrainWords;

  static int CardsPerRegion;

  // It sets up the heap region size (GrainBytes / GrainWords), as

  // well as other related fields that are based on the heap region

  // size (LogOfHRGrainBytes / LogOfHRGrainWords /

  // CardsPerRegion). All those fields are considered constant

  // throughout the JVM's execution, therefore they should only be set

  // up once during initialization time.

  static void setup_heap_region_size(uintx min_heap_size);

  enum ClaimValues {

    InitialClaimValue     = 0,

    FinalCountClaimValue  = 1,

    NoteEndClaimValue     = 2,

    ScrubRemSetClaimValue = 3,

    ParVerifyClaimValue   = 4,

    RebuildRSClaimValue   = 5

  };

  inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {

    assert(is_young(), "we can only skip BOT updates on young regions");

    return ContiguousSpace::par_allocate(word_size);

  }

  inline HeapWord* allocate_no_bot_updates(size_t word_size) {

    assert(is_young(), "we can only skip BOT updates on young regions");

    return ContiguousSpace::allocate(word_size);

  }

  // If this region is a member of a HeapRegionSeq, the index in that

  // sequence, otherwise -1.

  int hrs_index() const { return _hrs_index; }

  void set_hrs_index(int index) { _hrs_index = index; }

  // The number of bytes marked live in the region in the last marking phase.

  size_t marked_bytes()    { return _prev_marked_bytes; }

  // The number of bytes counted in the next marking.

  size_t next_marked_bytes() { return _next_marked_bytes; }

  // The number of bytes live wrt the next marking.

  size_t next_live_bytes() {

    return (top() - next_top_at_mark_start())

      * HeapWordSize

      + next_marked_bytes();

  }

  // A lower bound on the amount of garbage bytes in the region.

  size_t garbage_bytes() {

    size_t used_at_mark_start_bytes =

      (prev_top_at_mark_start() - bottom()) * HeapWordSize;

    assert(used_at_mark_start_bytes >= marked_bytes(),

           "Can't mark more than we have.");

    return used_at_mark_start_bytes - marked_bytes();

  }

  // An upper bound on the number of live bytes in the region.

  size_t max_live_bytes() { return used() - garbage_bytes(); }

  void add_to_marked_bytes(size_t incr_bytes) {

    _next_marked_bytes = _next_marked_bytes + incr_bytes;

    guarantee( _next_marked_bytes <= used(), "invariant" );

  }

  void zero_marked_bytes()      {

    _prev_marked_bytes = _next_marked_bytes = 0;

  }

  bool isHumongous() const { return _humongous_type != NotHumongous; }

  bool startsHumongous() const { return _humongous_type == StartsHumongous; }

  bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }

  // For a humongous region, region in which it starts.

  HeapRegion* humongous_start_region() const {

    return _humongous_start_region;

  }

  // Makes the current region be a "starts humongous" region, i.e.,

  // the first region in a series of one or more contiguous regions

  // that will contain a single "humongous" object. The two parameters

  // are as follows:

  //

  // new_top : The new value of the top field of this region which

  // points to the end of the humongous object that's being

  // allocated. If there is more than one region in the series, top

  // will lie beyond this region's original end field and on the last

  // region in the series.

  //

  // new_end : The new value of the end field of this region which

  // points to the end of the last region in the series. If there is

  // one region in the series (namely: this one) end will be the same

  // as the original end of this region.

  //

  // Updating top and end as described above makes this region look as

  // if it spans the entire space taken up by all the regions in the

  // series and an single allocation moved its top to new_top. This

  // ensures that the space (capacity / allocated) taken up by all

  // humongous regions can be calculated by just looking at the

  // "starts humongous" regions and by ignoring the "continues

  // humongous" regions.

  void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);

  // Makes the current region be a "continues humongous'

  // region. first_hr is the "start humongous" region of the series

  // which this region will be part of.

  void set_continuesHumongous(HeapRegion* first_hr);

  // If the region has a remembered set, return a pointer to it.

  HeapRegionRemSet* rem_set() const {

    return _rem_set;

  }

  // True iff the region is in current collection_set.

  bool in_collection_set() const {

    return _in_collection_set;

  }

  void set_in_collection_set(bool b) {

    _in_collection_set = b;

  }

  HeapRegion* next_in_collection_set() {

    assert(in_collection_set(), "should only invoke on member of CS.");

    assert(_next_in_special_set == NULL ||

           _next_in_special_set->in_collection_set(),

           "Malformed CS.");

    return _next_in_special_set;

  }

  void set_next_in_collection_set(HeapRegion* r) {

    assert(in_collection_set(), "should only invoke on member of CS.");

    assert(r == NULL || r->in_collection_set(), "Malformed CS.");

    _next_in_special_set = r;

  }

  // True iff it is or has been an allocation region in the current

  // collection pause.

  bool is_gc_alloc_region() const {

    return _is_gc_alloc_region;

  }

  void set_is_gc_alloc_region(bool b) {

    _is_gc_alloc_region = b;

  }

  HeapRegion* next_gc_alloc_region() {

    assert(is_gc_alloc_region(), "should only invoke on member of CS.");

    assert(_next_in_special_set == NULL ||

           _next_in_special_set->is_gc_alloc_region(),

           "Malformed CS.");

    return _next_in_special_set;

  }

  void set_next_gc_alloc_region(HeapRegion* r) {

    assert(is_gc_alloc_region(), "should only invoke on member of CS.");

    assert(r == NULL || r->is_gc_alloc_region(), "Malformed CS.");

    _next_in_special_set = r;

  }