/*

 * Copyright 2001-2009 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.

 *

 */

#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;

};

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;

    // True iff the region is on the unclean list, waiting to be zero filled.

  bool _is_on_unclean_list;

  // True iff the region is on the free list, ready for allocation.

  bool _is_on_free_list;

  // 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;

  // 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

    ScanOnly,                   // a region is young and scan-only

    Young,                      // a region is young

    Survivor                    // a region is young and it contains

                                // survivor

  };

  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;

  }

  jint _zfs;  // A member of ZeroFillState.  Protected by ZF_lock.

  Thread* _zero_filler; // If _zfs is ZeroFilling, the thread that (last)

                        // made it so.

  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;

  }

 public:

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

  HeapRegion(G1BlockOffsetSharedArray* sharedOffsetArray,

             MemRegion mr, bool is_zeroed);

  enum SomePublicConstants {

    // HeapRegions are GrainBytes-aligned

    // and have sizes that are multiples of GrainBytes.

    LogOfHRGrainBytes = 20,

    LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize,

    GrainBytes = 1 << LogOfHRGrainBytes,

    GrainWords = 1 <<LogOfHRGrainWords,

    MaxAge = 2, NoOfAges = MaxAge+1

  };

  enum ClaimValues {

    InitialClaimValue     = 0,

    FinalCountClaimValue  = 1,

    NoteEndClaimValue     = 2,

    ScrubRemSetClaimValue = 3,

    ParVerifyClaimValue   = 4,

    RebuildRSClaimValue   = 5

  };

  // Concurrent refinement requires contiguous heap regions (in which TLABs

  // might be allocated) to be zero-filled.  Each region therefore has a

  // zero-fill-state.

  enum ZeroFillState {

    NotZeroFilled,

    ZeroFilling,

    ZeroFilled,

    Allocated

  };

  // 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;

  }

  // Causes the current region to represent a humongous object spanning "n"

  // regions.

  virtual void set_startsHumongous();

  // The regions that continue a humongous sequence should be added using

  // this method, in increasing address order.

  void set_continuesHumongous(HeapRegion* start);

  void add_continuingHumongousRegion(HeapRegion* cont);

  // 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;

  }

  bool is_on_free_list() {

    return _is_on_free_list;

  }

  void set_on_free_list(bool b) {

    _is_on_free_list = b;

  }

  HeapRegion* next_from_free_list() {

    assert(is_on_free_list(),

           "Should only invoke on free space.");

    assert(_next_in_special_set == NULL ||

           _next_in_special_set->is_on_free_list(),

           "Malformed Free List.");

    return _next_in_special_set;

  }

  void set_next_on_free_list(HeapRegion* r) {

    assert(r == NULL || r->is_on_free_list(), "Malformed free list.");

    _next_in_special_set = r;

  }

  bool is_on_unclean_list() {

    return _is_on_unclean_list;

  }

  void set_on_unclean_list(bool b);

  HeapRegion* next_from_unclean_list() {

    assert(is_on_unclean_list(),

           "Should only invoke on unclean space.");

    assert(_next_in_special_set == NULL ||

           _next_in_special_set->is_on_unclean_list(),

           "Malformed unclean List.");

    return _next_in_special_set;

  }

  void set_next_on_unclean_list(HeapRegion* r);

  HeapRegion* get_next_young_region() { return _next_young_region; }

  void set_next_young_region(HeapRegion* hr) {

    _next_young_region = hr;

  }

  // Allows logical separation between objects allocated before and after.

  void save_marks();

  // Reset HR stuff to default values.

  void hr_clear(bool par, bool clear_space);

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

  // Ensure that "this" is zero-filled.

  void ensure_zero_filled();

  // This one requires that the calling thread holds ZF_mon.

  void ensure_zero_filled_locked();

  // Get the start of the unmarked area in this region.

  HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }

  HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }

  // Apply "cl->do_oop" to (the addresses of) all reference fields in objects

  // allocated in the current region before the last call to "save_mark".

  void oop_before_save_marks_iterate(OopClosure* cl);

  // This call determines the "filter kind" argument that will be used for

  // the next call to "new_dcto_cl" on this region with the "traditional"

  // signature (i.e., the call below.)  The default, in the absence of a

  // preceding call to this method, is "NoFilterKind", and a call to this

  // method is necessary for each such call, or else it reverts to the

  // default.

  // (This is really ugly, but all other methods I could think of changed a

  // lot of main-line code for G1.)

  void set_next_filter_kind(HeapRegionDCTOC::FilterKind nfk) {

    _next_fk = nfk;

  }

  DirtyCardToOopClosure*

  new_dcto_closure(OopClosure* cl,

                   CardTableModRefBS::PrecisionStyle precision,

                   HeapRegionDCTOC::FilterKind fk);

#if WHASSUP

  DirtyCardToOopClosure*

  new_dcto_closure(OopClosure* cl,

                   CardTableModRefBS::PrecisionStyle precision,

                   HeapWord* boundary) {

    assert(boundary == NULL, "This arg doesn't make sense here.");

    DirtyCardToOopClosure* res = new_dcto_closure(cl, precision, _next_fk);

    _next_fk = HeapRegionDCTOC::NoFilterKind;

    return res;

  }

#endif

  //

  // Note the start or end of marking. This tells the heap region

  // that the collector is about to start or has finished (concurrently)

  // marking the heap.

  //