heapRegion.hpp 30.8 KB
Newer Older
1
/*
2
 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
 * 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.
 *
19 20 21
 * 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.
22 23 24
 *
 */

25 26 27 28 29 30 31 32 33 34 35
#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"

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
#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;
53 54
class HeapRegionSetBase;

55 56 57 58 59
#define HR_FORMAT SIZE_FORMAT":(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
#define HR_FORMAT_PARAMS(_hr_) \
                (_hr_)->hrs_index(), \
                (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : "-", \
                (_hr_)->bottom(), (_hr_)->top(), (_hr_)->end()
60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152

// 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;
153 154 155 156 157 158 159
  // 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;
160 161 162 163 164 165 166 167 168 169 170 171 172 173

 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; }

174 175 176 177 178 179 180 181 182 183 184
  // 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; }

T
Merge  
tonyp 已提交
185 186
  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
  virtual void clear(bool mangle_space);
187 188 189 190 191 192 193 194 195 196 197 198 199

  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;
200 201 202 203 204 205 206 207 208 209 210 211 212

  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);
  }
213 214 215 216 217 218
};

class HeapRegion: public G1OffsetTableContigSpace {
  friend class VMStructs;
 private:

219 220 221 222 223 224
  enum HumongousType {
    NotHumongous = 0,
    StartsHumongous,
    ContinuesHumongous
  };

225 226 227 228 229 230 231 232 233 234 235 236
  // 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:
237 238
  // The index of this region in the heap region sequence.
  size_t  _hrs_index;
239

240
  HumongousType _humongous_type;
241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262
  // 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;

263 264 265
  // Next region whose cards need cleaning
  HeapRegion* _next_dirty_cards_region;

266 267 268 269 270 271 272
  // Fields used by the HeapRegionSetBase class and subclasses.
  HeapRegion* _next;
#ifdef ASSERT
  HeapRegionSetBase* _containing_set;
#endif // ASSERT
  bool _pending_removal;

273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290
  // 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
291
    Survivor                    // a region is young and it contains survivors
292 293
  };

294
  volatile YoungType _young_type;
295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328
  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;
  }

329 330 331 332 333 334 335 336 337 338 339 340 341 342
  // 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;

343 344
 public:
  // If "is_zeroed" is "true", the region "mr" can be assumed to contain zeros.
345 346
  HeapRegion(size_t hrs_index,
             G1BlockOffsetSharedArray* sharedOffsetArray,
347 348
             MemRegion mr, bool is_zeroed);

349 350 351 352 353 354
  static int    LogOfHRGrainBytes;
  static int    LogOfHRGrainWords;

  static size_t GrainBytes;
  static size_t GrainWords;
  static size_t CardsPerRegion;
355

356 357 358 359 360
  static size_t align_up_to_region_byte_size(size_t sz) {
    return (sz + (size_t) GrainBytes - 1) &
                                      ~((1 << (size_t) LogOfHRGrainBytes) - 1);
  }

361 362 363 364 365 366 367
  // 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);
368

369
  enum ClaimValues {
370 371 372 373 374 375
    InitialClaimValue          = 0,
    FinalCountClaimValue       = 1,
    NoteEndClaimValue          = 2,
    ScrubRemSetClaimValue      = 3,
    ParVerifyClaimValue        = 4,
    RebuildRSClaimValue        = 5,
376 377
    CompleteMarkCSetClaimValue = 6,
    ParEvacFailureClaimValue   = 7
378 379
  };

380 381 382 383 384 385 386 387 388
  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);
  }

389 390
  // If this region is a member of a HeapRegionSeq, the index in that
  // sequence, otherwise -1.
391
  size_t hrs_index() const { return _hrs_index; }
392 393 394

  // The number of bytes marked live in the region in the last marking phase.
  size_t marked_bytes()    { return _prev_marked_bytes; }
395 396 397 398
  size_t live_bytes() {
    return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
  }

399 400 401 402
  // 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() {
403 404
    return
      (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420
  }

  // 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;
421
    assert(_next_marked_bytes <= used(), "invariant" );
422 423 424 425 426 427
  }

  void zero_marked_bytes()      {
    _prev_marked_bytes = _next_marked_bytes = 0;
  }

428 429 430
  bool isHumongous() const { return _humongous_type != NotHumongous; }
  bool startsHumongous() const { return _humongous_type == StartsHumongous; }
  bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
431 432 433 434 435
  // For a humongous region, region in which it starts.
  HeapRegion* humongous_start_region() const {
    return _humongous_start_region;
  }

436 437 438 439 440 441 442 443
  // 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;
  }

444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472
  // 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);
473

474 475 476
  // Unsets the humongous-related fields on the region.
  void set_notHumongous();

477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501
  // 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;
  }

502
  // Methods used by the HeapRegionSetBase class and subclasses.
503

504 505 506
  // Getter and setter for the next field used to link regions into
  // linked lists.
  HeapRegion* next()              { return _next; }
507

508
  void set_next(HeapRegion* next) { _next = next; }
509

510 511 512 513 514 515 516 517 518 519 520
  // Every region added to a set is tagged with a reference to that
  // set. This is used for doing consistency checking to make sure that
  // the contents of a set are as they should be and it's only
  // available in non-product builds.
#ifdef ASSERT
  void set_containing_set(HeapRegionSetBase* containing_set) {
    assert((containing_set == NULL && _containing_set != NULL) ||
           (containing_set != NULL && _containing_set == NULL),
           err_msg("containing_set: "PTR_FORMAT" "
                   "_containing_set: "PTR_FORMAT,
                   containing_set, _containing_set));
521

522
    _containing_set = containing_set;
T
tonyp 已提交
523
  }
524

525 526 527
  HeapRegionSetBase* containing_set() { return _containing_set; }
#else // ASSERT
  void set_containing_set(HeapRegionSetBase* containing_set) { }
528

T
tonyp 已提交
529
  // containing_set() is only used in asserts so there's no reason
530 531 532 533 534 535
  // to provide a dummy version of it.
#endif // ASSERT

  // If we want to remove regions from a list in bulk we can simply tag
  // them with the pending_removal tag and call the
  // remove_all_pending() method on the list.
536

537 538 539
  bool pending_removal() { return _pending_removal; }

  void set_pending_removal(bool pending_removal) {
T
tonyp 已提交
540 541 542 543 544 545 546 547 548
    if (pending_removal) {
      assert(!_pending_removal && containing_set() != NULL,
             "can only set pending removal to true if it's false and "
             "the region belongs to a region set");
    } else {
      assert( _pending_removal && containing_set() == NULL,
              "can only set pending removal to false if it's true and "
              "the region does not belong to a region set");
    }
549 550 551

    _pending_removal = pending_removal;
  }
552 553 554 555 556 557

  HeapRegion* get_next_young_region() { return _next_young_region; }
  void set_next_young_region(HeapRegion* hr) {
    _next_young_region = hr;
  }

558 559 560 561 562
  HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
  HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
  void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
  bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }

563 564
  HeapWord* orig_end() { return _orig_end; }

565 566 567 568 569
  // 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);
570
  void par_clear();
571

T
Merge  
tonyp 已提交
572
  void initialize(MemRegion mr, bool clear_space, bool mangle_space);
573 574 575 576 577 578 579 580 581 582 583 584 585

  // 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);

  // 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.

586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612
  // Notify the region that concurrent marking is starting. Initialize
  // all fields related to the next marking info.
  inline void note_start_of_marking();

  // Notify the region that concurrent marking has finished. Copy the
  // (now finalized) next marking info fields into the prev marking
  // info fields.
  inline void note_end_of_marking();

  // Notify the region that it will be used as to-space during a GC
  // and we are about to start copying objects into it.
  inline void note_start_of_copying(bool during_initial_mark);

  // Notify the region that it ceases being to-space during a GC and
  // we will not copy objects into it any more.
  inline void note_end_of_copying(bool during_initial_mark);

  // Notify the region that we are about to start processing
  // self-forwarded objects during evac failure handling.
  void note_self_forwarding_removal_start(bool during_initial_mark,
                                          bool during_conc_mark);

  // Notify the region that we have finished processing self-forwarded
  // objects during evac failure handling.
  void note_self_forwarding_removal_end(bool during_initial_mark,
                                        bool during_conc_mark,
                                        size_t marked_bytes);
613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753

  // Returns "false" iff no object in the region was allocated when the
  // last mark phase ended.
  bool is_marked() { return _prev_top_at_mark_start != bottom(); }

  // If "is_marked()" is true, then this is the index of the region in
  // an array constructed at the end of marking of the regions in a
  // "desirability" order.
  int sort_index() {
    return _sort_index;
  }
  void set_sort_index(int i) {
    _sort_index = i;
  }

  void init_top_at_conc_mark_count() {
    _top_at_conc_mark_count = bottom();
  }

  void set_top_at_conc_mark_count(HeapWord *cur) {
    assert(bottom() <= cur && cur <= end(), "Sanity.");
    _top_at_conc_mark_count = cur;
  }

  HeapWord* top_at_conc_mark_count() {
    return _top_at_conc_mark_count;
  }

  void reset_during_compaction() {
    guarantee( isHumongous() && startsHumongous(),
               "should only be called for humongous regions");

    zero_marked_bytes();
    init_top_at_mark_start();
  }

  // <PREDICTION>
  void calc_gc_efficiency(void);
  double gc_efficiency() { return _gc_efficiency;}
  // </PREDICTION>

  bool is_young() const     { return _young_type != NotYoung; }
  bool is_survivor() const  { return _young_type == Survivor; }

  int  young_index_in_cset() const { return _young_index_in_cset; }
  void set_young_index_in_cset(int index) {
    assert( (index == -1) || is_young(), "pre-condition" );
    _young_index_in_cset = index;
  }

  int age_in_surv_rate_group() {
    assert( _surv_rate_group != NULL, "pre-condition" );
    assert( _age_index > -1, "pre-condition" );
    return _surv_rate_group->age_in_group(_age_index);
  }

  void record_surv_words_in_group(size_t words_survived) {
    assert( _surv_rate_group != NULL, "pre-condition" );
    assert( _age_index > -1, "pre-condition" );
    int age_in_group = age_in_surv_rate_group();
    _surv_rate_group->record_surviving_words(age_in_group, words_survived);
  }

  int age_in_surv_rate_group_cond() {
    if (_surv_rate_group != NULL)
      return age_in_surv_rate_group();
    else
      return -1;
  }

  SurvRateGroup* surv_rate_group() {
    return _surv_rate_group;
  }

  void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
    assert( surv_rate_group != NULL, "pre-condition" );
    assert( _surv_rate_group == NULL, "pre-condition" );
    assert( is_young(), "pre-condition" );

    _surv_rate_group = surv_rate_group;
    _age_index = surv_rate_group->next_age_index();
  }

  void uninstall_surv_rate_group() {
    if (_surv_rate_group != NULL) {
      assert( _age_index > -1, "pre-condition" );
      assert( is_young(), "pre-condition" );

      _surv_rate_group = NULL;
      _age_index = -1;
    } else {
      assert( _age_index == -1, "pre-condition" );
    }
  }

  void set_young() { set_young_type(Young); }

  void set_survivor() { set_young_type(Survivor); }

  void set_not_young() { set_young_type(NotYoung); }

  // Determine if an object has been allocated since the last
  // mark performed by the collector. This returns true iff the object
  // is within the unmarked area of the region.
  bool obj_allocated_since_prev_marking(oop obj) const {
    return (HeapWord *) obj >= prev_top_at_mark_start();
  }
  bool obj_allocated_since_next_marking(oop obj) const {
    return (HeapWord *) obj >= next_top_at_mark_start();
  }

  // For parallel heapRegion traversal.
  bool claimHeapRegion(int claimValue);
  jint claim_value() { return _claimed; }
  // Use this carefully: only when you're sure no one is claiming...
  void set_claim_value(int claimValue) { _claimed = claimValue; }

  // Returns the "evacuation_failed" property of the region.
  bool evacuation_failed() { return _evacuation_failed; }

  // Sets the "evacuation_failed" property of the region.
  void set_evacuation_failed(bool b) {
    _evacuation_failed = b;

    if (b) {
      init_top_at_conc_mark_count();
      _next_marked_bytes = 0;
    }
  }

  // Requires that "mr" be entirely within the region.
  // Apply "cl->do_object" to all objects that intersect with "mr".
  // If the iteration encounters an unparseable portion of the region,
  // or if "cl->abort()" is true after a closure application,
  // terminate the iteration and return the address of the start of the
  // subregion that isn't done.  (The two can be distinguished by querying
  // "cl->abort()".)  Return of "NULL" indicates that the iteration
  // completed.
  HeapWord*
  object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);

754 755 756 757 758
  // filter_young: if true and the region is a young region then we
  // skip the iteration.
  // card_ptr: if not NULL, and we decide that the card is not young
  // and we iterate over it, we'll clean the card before we start the
  // iteration.
759 760
  HeapWord*
  oops_on_card_seq_iterate_careful(MemRegion mr,
761
                                   FilterOutOfRegionClosure* cl,
762 763
                                   bool filter_young,
                                   jbyte* card_ptr);
764 765 766 767 768 769 770 771 772 773 774 775 776

  // A version of block start that is guaranteed to find *some* block
  // boundary at or before "p", but does not object iteration, and may
  // therefore be used safely when the heap is unparseable.
  HeapWord* block_start_careful(const void* p) const {
    return _offsets.block_start_careful(p);
  }

  // Requires that "addr" is within the region.  Returns the start of the
  // first ("careful") block that starts at or after "addr", or else the
  // "end" of the region if there is no such block.
  HeapWord* next_block_start_careful(HeapWord* addr);

777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792
  size_t recorded_rs_length() const        { return _recorded_rs_length; }
  double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
  size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }

  void set_recorded_rs_length(size_t rs_length) {
    _recorded_rs_length = rs_length;
  }

  void set_predicted_elapsed_time_ms(double ms) {
    _predicted_elapsed_time_ms = ms;
  }

  void set_predicted_bytes_to_copy(size_t bytes) {
    _predicted_bytes_to_copy = bytes;
  }

793 794 795 796 797 798 799 800 801 802 803
#define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)  \
  virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
  SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL)

  CompactibleSpace* next_compaction_space() const;

  virtual void reset_after_compaction();

  void print() const;
  void print_on(outputStream* st) const;

804 805 806 807
  // vo == UsePrevMarking  -> use "prev" marking information,
  // vo == UseNextMarking -> use "next" marking information
  // vo == UseMarkWord    -> use the mark word in the object header
  //
808 809
  // NOTE: Only the "prev" marking information is guaranteed to be
  // consistent most of the time, so most calls to this should use
810 811 812 813 814 815 816 817
  // vo == UsePrevMarking.
  // Currently, there is only one case where this is called with
  // vo == UseNextMarking, which is to verify the "next" marking
  // information at the end of remark.
  // Currently there is only one place where this is called with
  // vo == UseMarkWord, which is to verify the marking during a
  // full GC.
  void verify(bool allow_dirty, VerifyOption vo, bool *failures) const;
818 819

  // Override; it uses the "prev" marking information
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843
  virtual void verify(bool allow_dirty) const;
};

// HeapRegionClosure is used for iterating over regions.
// Terminates the iteration when the "doHeapRegion" method returns "true".
class HeapRegionClosure : public StackObj {
  friend class HeapRegionSeq;
  friend class G1CollectedHeap;

  bool _complete;
  void incomplete() { _complete = false; }

 public:
  HeapRegionClosure(): _complete(true) {}

  // Typically called on each region until it returns true.
  virtual bool doHeapRegion(HeapRegion* r) = 0;

  // True after iteration if the closure was applied to all heap regions
  // and returned "false" in all cases.
  bool complete() { return _complete; }
};

#endif // SERIALGC
844 845

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP