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 *

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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"

#include "utilities/macros.hpp"

#if INCLUDE_ALL_GCS

// 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;

class HeapRegionSetBase;

#define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"

#define HR_FORMAT_PARAMS(_hr_) \

                (_hr_)->hrs_index(), \

                (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \

                (_hr_)->startsHumongous() ? "HS" : \

                (_hr_)->continuesHumongous() ? "HC" : \

                !(_hr_)->is_empty() ? "O" : "F", \

                (_hr_)->bottom(), (_hr_)->top(), (_hr_)->end()

// sentinel value for hrs_index

#define G1_NULL_HRS_INDEX ((uint) -1)

// 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,

                               ExtendedOopClosure* 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,

                                             (ExtendedOopClosure*)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, ExtendedOopClosure* 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;

  // When we need to retire an allocation region, while other threads

  // are also concurrently trying to allocate into it, we typically

  // allocate a dummy object at the end of the region to ensure that

  // no more allocations can take place in it. However, sometimes we

  // want to know where the end of the last "real" object we allocated

  // into the region was and this is what this keeps track.

  HeapWord* _pre_dummy_top;

 public:

  G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,

                           MemRegion mr);

  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; }

  unsigned get_gc_time_stamp() { return _gc_time_stamp; }

  // See the comment above in the declaration of _pre_dummy_top for an

  // explanation of what it is.

  void set_pre_dummy_top(HeapWord* pre_dummy_top) {

    assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");

    _pre_dummy_top = pre_dummy_top;

  }

  HeapWord* pre_dummy_top() {

    return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;

  }

  void reset_pre_dummy_top() { _pre_dummy_top = NULL; }

  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

  };

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

  // with an object.

  void oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* 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:

  // The index of this region in the heap region sequence.

  uint  _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;

  // 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;

  // Fields used by the HeapRegionSetBase class and subclasses.

  HeapRegion* _next;

#ifdef ASSERT

  HeapRegionSetBase* _containing_set;

#endif // ASSERT

  bool _pending_removal;

  // 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.

  // The calculated GC efficiency of the region.

  double _gc_efficiency;

  enum YoungType {

    NotYoung,                   // a region is not young

    Young,                      // a region is young

    Survivor                    // a region is young and it contains survivors

  };

  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.

  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;

  }

  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:

  HeapRegion(uint hrs_index,

             G1BlockOffsetSharedArray* sharedOffsetArray,

             MemRegion mr);

  static int    LogOfHRGrainBytes;

  static int    LogOfHRGrainWords;

  static size_t GrainBytes;

  static size_t GrainWords;

  static size_t CardsPerRegion;

  static size_t align_up_to_region_byte_size(size_t sz) {

    return (sz + (size_t) GrainBytes - 1) &

                                      ~((1 << (size_t) LogOfHRGrainBytes) - 1);

  }

  // 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,

    ParEvacFailureClaimValue   = 6,

    AggregateCountClaimValue   = 7,

    VerifyCountClaimValue      = 8

  };

  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.

  uint hrs_index() const { return _hrs_index; }

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

  size_t marked_bytes()    { return _prev_marked_bytes; }

  size_t live_bytes() {

    return (top() - prev_top_at_mark_start()) * HeapWordSize + 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();

  }

  // Return the amount of bytes we'll reclaim if we collect this

  // region. This includes not only the known garbage bytes in the

  // region but also any unallocated space in it, i.e., [top, end),

  // since it will also be reclaimed if we collect the region.

  size_t reclaimable_bytes() {

    size_t known_live_bytes = live_bytes();

    assert(known_live_bytes <= capacity(), "sanity");

    return capacity() - known_live_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;

    assert(_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;

  }

  // Return the number of distinct regions that are covered by this region:

  // 1 if the region is not humongous, >= 1 if the region is humongous.

  uint region_num() const {

    if (!isHumongous()) {

      return 1U;

    } else {

      assert(startsHumongous(), "doesn't make sense on HC regions");

      assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");

      return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);

    }

  }

  // Return the index + 1 of the last HC regions that's associated

  // with this HS region.

  uint last_hc_index() const {

    assert(startsHumongous(), "don't call this otherwise");

    return hrs_index() + region_num();

  }

  // Same as Space::is_in_reserved, but will use the original size of the region.

  // The original size is different only for start humongous regions. They get

  // their _end set up to be the end of the last continues region of the

  // corresponding humongous object.

  bool is_in_reserved_raw(const void* p) const {

    return _bottom <= p && p < _orig_end;

  }

  // 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);

  // Unsets the humongous-related fields on the region.

  void set_notHumongous();

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

  HeapRegionRemSet* rem_set() const {

    return _rem_set;

  }