rev 4008 : 8001985: G1: Backport fix for 7200261 to hsx24
Summary: The automatic backport of the fix for 7200261 did not apply cleanly to hsx24 - there were two rejected hunks that had to be fixed up by hand.
Reviewed-by:

   1 /*
   2  * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
  27 
  28 #include "gc_implementation/g1/heapRegionSets.hpp"
  29 #include "utilities/taskqueue.hpp"
  30 
  31 class G1CollectedHeap;
  32 class CMTask;
  33 typedef GenericTaskQueue<oop, mtGC>            CMTaskQueue;
  34 typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
  35 
  36 // Closure used by CM during concurrent reference discovery
  37 // and reference processing (during remarking) to determine
  38 // if a particular object is alive. It is primarily used
  39 // to determine if referents of discovered reference objects
  40 // are alive. An instance is also embedded into the
  41 // reference processor as the _is_alive_non_header field
  42 class G1CMIsAliveClosure: public BoolObjectClosure {
  43   G1CollectedHeap* _g1;
  44  public:
  45   G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
  46 
  47   void do_object(oop obj) {
  48     ShouldNotCallThis();
  49   }
  50   bool do_object_b(oop obj);
  51 };
  52 
  53 // A generic CM bit map.  This is essentially a wrapper around the BitMap
  54 // class, with one bit per (1<<_shifter) HeapWords.
  55 
  56 class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
  57  protected:
  58   HeapWord* _bmStartWord;      // base address of range covered by map
  59   size_t    _bmWordSize;       // map size (in #HeapWords covered)
  60   const int _shifter;          // map to char or bit
  61   VirtualSpace _virtual_space; // underlying the bit map
  62   BitMap    _bm;               // the bit map itself
  63 
  64  public:
  65   // constructor
  66   CMBitMapRO(ReservedSpace rs, int shifter);
  67 
  68   enum { do_yield = true };
  69 
  70   // inquiries
  71   HeapWord* startWord()   const { return _bmStartWord; }
  72   size_t    sizeInWords() const { return _bmWordSize;  }
  73   // the following is one past the last word in space
  74   HeapWord* endWord()     const { return _bmStartWord + _bmWordSize; }
  75 
  76   // read marks
  77 
  78   bool isMarked(HeapWord* addr) const {
  79     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
  80            "outside underlying space?");
  81     return _bm.at(heapWordToOffset(addr));
  82   }
  83 
  84   // iteration
  85   inline bool iterate(BitMapClosure* cl, MemRegion mr);
  86   inline bool iterate(BitMapClosure* cl);
  87 
  88   // Return the address corresponding to the next marked bit at or after
  89   // "addr", and before "limit", if "limit" is non-NULL.  If there is no
  90   // such bit, returns "limit" if that is non-NULL, or else "endWord()".
  91   HeapWord* getNextMarkedWordAddress(HeapWord* addr,
  92                                      HeapWord* limit = NULL) const;
  93   // Return the address corresponding to the next unmarked bit at or after
  94   // "addr", and before "limit", if "limit" is non-NULL.  If there is no
  95   // such bit, returns "limit" if that is non-NULL, or else "endWord()".
  96   HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
  97                                        HeapWord* limit = NULL) const;
  98 
  99   // conversion utilities
 100   // XXX Fix these so that offsets are size_t's...
 101   HeapWord* offsetToHeapWord(size_t offset) const {
 102     return _bmStartWord + (offset << _shifter);
 103   }
 104   size_t heapWordToOffset(HeapWord* addr) const {
 105     return pointer_delta(addr, _bmStartWord) >> _shifter;
 106   }
 107   int heapWordDiffToOffsetDiff(size_t diff) const;
 108   HeapWord* nextWord(HeapWord* addr) {
 109     return offsetToHeapWord(heapWordToOffset(addr) + 1);
 110   }
 111 
 112   // debugging
 113   NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
 114 };
 115 
 116 class CMBitMap : public CMBitMapRO {
 117 
 118  public:
 119   // constructor
 120   CMBitMap(ReservedSpace rs, int shifter) :
 121     CMBitMapRO(rs, shifter) {}
 122 
 123   // write marks
 124   void mark(HeapWord* addr) {
 125     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 126            "outside underlying space?");
 127     _bm.set_bit(heapWordToOffset(addr));
 128   }
 129   void clear(HeapWord* addr) {
 130     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 131            "outside underlying space?");
 132     _bm.clear_bit(heapWordToOffset(addr));
 133   }
 134   bool parMark(HeapWord* addr) {
 135     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 136            "outside underlying space?");
 137     return _bm.par_set_bit(heapWordToOffset(addr));
 138   }
 139   bool parClear(HeapWord* addr) {
 140     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 141            "outside underlying space?");
 142     return _bm.par_clear_bit(heapWordToOffset(addr));
 143   }
 144   void markRange(MemRegion mr);
 145   void clearAll();
 146   void clearRange(MemRegion mr);
 147 
 148   // Starting at the bit corresponding to "addr" (inclusive), find the next
 149   // "1" bit, if any.  This bit starts some run of consecutive "1"'s; find
 150   // the end of this run (stopping at "end_addr").  Return the MemRegion
 151   // covering from the start of the region corresponding to the first bit
 152   // of the run to the end of the region corresponding to the last bit of
 153   // the run.  If there is no "1" bit at or after "addr", return an empty
 154   // MemRegion.
 155   MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
 156 };
 157 
 158 // Represents a marking stack used by the CM collector.
 159 // Ideally this should be GrowableArray<> just like MSC's marking stack(s).
 160 class CMMarkStack VALUE_OBJ_CLASS_SPEC {
 161   ConcurrentMark* _cm;
 162   oop*   _base;        // bottom of stack
 163   jint   _index;       // one more than last occupied index
 164   jint   _capacity;    // max #elements
 165   jint   _saved_index; // value of _index saved at start of GC
 166   NOT_PRODUCT(jint _max_depth;)  // max depth plumbed during run
 167 
 168   bool   _overflow;
 169   DEBUG_ONLY(bool _drain_in_progress;)
 170   DEBUG_ONLY(bool _drain_in_progress_yields;)
 171 
 172  public:
 173   CMMarkStack(ConcurrentMark* cm);
 174   ~CMMarkStack();
 175 
 176   void allocate(size_t size);
 177 
 178   oop pop() {
 179     if (!isEmpty()) {
 180       return _base[--_index] ;
 181     }
 182     return NULL;
 183   }
 184 
 185   // If overflow happens, don't do the push, and record the overflow.
 186   // *Requires* that "ptr" is already marked.
 187   void push(oop ptr) {
 188     if (isFull()) {
 189       // Record overflow.
 190       _overflow = true;
 191       return;
 192     } else {
 193       _base[_index++] = ptr;
 194       NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
 195     }
 196   }
 197   // Non-block impl.  Note: concurrency is allowed only with other
 198   // "par_push" operations, not with "pop" or "drain".  We would need
 199   // parallel versions of them if such concurrency was desired.
 200   void par_push(oop ptr);
 201 
 202   // Pushes the first "n" elements of "ptr_arr" on the stack.
 203   // Non-block impl.  Note: concurrency is allowed only with other
 204   // "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
 205   void par_adjoin_arr(oop* ptr_arr, int n);
 206 
 207   // Pushes the first "n" elements of "ptr_arr" on the stack.
 208   // Locking impl: concurrency is allowed only with
 209   // "par_push_arr" and/or "par_pop_arr" operations, which use the same
 210   // locking strategy.
 211   void par_push_arr(oop* ptr_arr, int n);
 212 
 213   // If returns false, the array was empty.  Otherwise, removes up to "max"
 214   // elements from the stack, and transfers them to "ptr_arr" in an
 215   // unspecified order.  The actual number transferred is given in "n" ("n
 216   // == 0" is deliberately redundant with the return value.)  Locking impl:
 217   // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
 218   // operations, which use the same locking strategy.
 219   bool par_pop_arr(oop* ptr_arr, int max, int* n);
 220 
 221   // Drain the mark stack, applying the given closure to all fields of
 222   // objects on the stack.  (That is, continue until the stack is empty,
 223   // even if closure applications add entries to the stack.)  The "bm"
 224   // argument, if non-null, may be used to verify that only marked objects
 225   // are on the mark stack.  If "yield_after" is "true", then the
 226   // concurrent marker performing the drain offers to yield after
 227   // processing each object.  If a yield occurs, stops the drain operation
 228   // and returns false.  Otherwise, returns true.
 229   template<class OopClosureClass>
 230   bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
 231 
 232   bool isEmpty()    { return _index == 0; }
 233   bool isFull()     { return _index == _capacity; }
 234   int maxElems()    { return _capacity; }
 235 
 236   bool overflow() { return _overflow; }
 237   void clear_overflow() { _overflow = false; }
 238 
 239   int  size() { return _index; }
 240 
 241   void setEmpty()   { _index = 0; clear_overflow(); }
 242 
 243   // Record the current index.
 244   void note_start_of_gc();
 245 
 246   // Make sure that we have not added any entries to the stack during GC.
 247   void note_end_of_gc();
 248 
 249   // iterate over the oops in the mark stack, up to the bound recorded via
 250   // the call above.
 251   void oops_do(OopClosure* f);
 252 };
 253 
 254 class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {
 255 private:
 256 #ifndef PRODUCT
 257   uintx _num_remaining;
 258   bool _force;
 259 #endif // !defined(PRODUCT)
 260 
 261 public:
 262   void init() PRODUCT_RETURN;
 263   void update() PRODUCT_RETURN;
 264   bool should_force() PRODUCT_RETURN_( return false; );
 265 };
 266 
 267 // this will enable a variety of different statistics per GC task
 268 #define _MARKING_STATS_       0
 269 // this will enable the higher verbose levels
 270 #define _MARKING_VERBOSE_     0
 271 
 272 #if _MARKING_STATS_
 273 #define statsOnly(statement)  \
 274 do {                          \
 275   statement ;                 \
 276 } while (0)
 277 #else // _MARKING_STATS_
 278 #define statsOnly(statement)  \
 279 do {                          \
 280 } while (0)
 281 #endif // _MARKING_STATS_
 282 
 283 typedef enum {
 284   no_verbose  = 0,   // verbose turned off
 285   stats_verbose,     // only prints stats at the end of marking
 286   low_verbose,       // low verbose, mostly per region and per major event
 287   medium_verbose,    // a bit more detailed than low
 288   high_verbose       // per object verbose
 289 } CMVerboseLevel;
 290 
 291 class YoungList;
 292 
 293 // Root Regions are regions that are not empty at the beginning of a
 294 // marking cycle and which we might collect during an evacuation pause
 295 // while the cycle is active. Given that, during evacuation pauses, we
 296 // do not copy objects that are explicitly marked, what we have to do
 297 // for the root regions is to scan them and mark all objects reachable
 298 // from them. According to the SATB assumptions, we only need to visit
 299 // each object once during marking. So, as long as we finish this scan
 300 // before the next evacuation pause, we can copy the objects from the
 301 // root regions without having to mark them or do anything else to them.
 302 //
 303 // Currently, we only support root region scanning once (at the start
 304 // of the marking cycle) and the root regions are all the survivor
 305 // regions populated during the initial-mark pause.
 306 class CMRootRegions VALUE_OBJ_CLASS_SPEC {
 307 private:
 308   YoungList*           _young_list;
 309   ConcurrentMark*      _cm;
 310 
 311   volatile bool        _scan_in_progress;
 312   volatile bool        _should_abort;
 313   HeapRegion* volatile _next_survivor;
 314 
 315 public:
 316   CMRootRegions();
 317   // We actually do most of the initialization in this method.
 318   void init(G1CollectedHeap* g1h, ConcurrentMark* cm);
 319 
 320   // Reset the claiming / scanning of the root regions.
 321   void prepare_for_scan();
 322 
 323   // Forces get_next() to return NULL so that the iteration aborts early.
 324   void abort() { _should_abort = true; }
 325 
 326   // Return true if the CM thread are actively scanning root regions,
 327   // false otherwise.
 328   bool scan_in_progress() { return _scan_in_progress; }
 329 
 330   // Claim the next root region to scan atomically, or return NULL if
 331   // all have been claimed.
 332   HeapRegion* claim_next();
 333 
 334   // Flag that we're done with root region scanning and notify anyone
 335   // who's waiting on it. If aborted is false, assume that all regions
 336   // have been claimed.
 337   void scan_finished();
 338 
 339   // If CM threads are still scanning root regions, wait until they
 340   // are done. Return true if we had to wait, false otherwise.
 341   bool wait_until_scan_finished();
 342 };
 343 
 344 class ConcurrentMarkThread;
 345 
 346 class ConcurrentMark: public CHeapObj<mtGC> {
 347   friend class ConcurrentMarkThread;
 348   friend class CMTask;
 349   friend class CMBitMapClosure;
 350   friend class CMGlobalObjectClosure;
 351   friend class CMRemarkTask;
 352   friend class CMConcurrentMarkingTask;
 353   friend class G1ParNoteEndTask;
 354   friend class CalcLiveObjectsClosure;
 355   friend class G1CMRefProcTaskProxy;
 356   friend class G1CMRefProcTaskExecutor;
 357   friend class G1CMParKeepAliveAndDrainClosure;
 358   friend class G1CMParDrainMarkingStackClosure;
 359 
 360 protected:
 361   ConcurrentMarkThread* _cmThread;   // the thread doing the work
 362   G1CollectedHeap*      _g1h;        // the heap.
 363   uint                  _parallel_marking_threads; // the number of marking
 364                                                    // threads we're use
 365   uint                  _max_parallel_marking_threads; // max number of marking
 366                                                    // threads we'll ever use
 367   double                _sleep_factor; // how much we have to sleep, with
 368                                        // respect to the work we just did, to
 369                                        // meet the marking overhead goal
 370   double                _marking_task_overhead; // marking target overhead for
 371                                                 // a single task
 372 
 373   // same as the two above, but for the cleanup task
 374   double                _cleanup_sleep_factor;
 375   double                _cleanup_task_overhead;
 376 
 377   FreeRegionList        _cleanup_list;
 378 
 379   // Concurrent marking support structures
 380   CMBitMap                _markBitMap1;
 381   CMBitMap                _markBitMap2;
 382   CMBitMapRO*             _prevMarkBitMap; // completed mark bitmap
 383   CMBitMap*               _nextMarkBitMap; // under-construction mark bitmap
 384 
 385   BitMap                  _region_bm;
 386   BitMap                  _card_bm;
 387 
 388   // Heap bounds
 389   HeapWord*               _heap_start;
 390   HeapWord*               _heap_end;
 391 
 392   // Root region tracking and claiming.
 393   CMRootRegions           _root_regions;
 394 
 395   // For gray objects
 396   CMMarkStack             _markStack; // Grey objects behind global finger.
 397   HeapWord* volatile      _finger;  // the global finger, region aligned,
 398                                     // always points to the end of the
 399                                     // last claimed region
 400 
 401   // marking tasks
 402   uint                    _max_task_num; // maximum task number
 403   uint                    _active_tasks; // task num currently active
 404   CMTask**                _tasks;        // task queue array (max_task_num len)
 405   CMTaskQueueSet*         _task_queues;  // task queue set
 406   ParallelTaskTerminator  _terminator;   // for termination
 407 
 408   // Two sync barriers that are used to synchronise tasks when an
 409   // overflow occurs. The algorithm is the following. All tasks enter
 410   // the first one to ensure that they have all stopped manipulating
 411   // the global data structures. After they exit it, they re-initialise
 412   // their data structures and task 0 re-initialises the global data
 413   // structures. Then, they enter the second sync barrier. This
 414   // ensure, that no task starts doing work before all data
 415   // structures (local and global) have been re-initialised. When they
 416   // exit it, they are free to start working again.
 417   WorkGangBarrierSync     _first_overflow_barrier_sync;
 418   WorkGangBarrierSync     _second_overflow_barrier_sync;
 419 
 420   // this is set by any task, when an overflow on the global data
 421   // structures is detected.
 422   volatile bool           _has_overflown;
 423   // true: marking is concurrent, false: we're in remark
 424   volatile bool           _concurrent;
 425   // set at the end of a Full GC so that marking aborts
 426   volatile bool           _has_aborted;
 427 
 428   // used when remark aborts due to an overflow to indicate that
 429   // another concurrent marking phase should start
 430   volatile bool           _restart_for_overflow;
 431 
 432   // This is true from the very start of concurrent marking until the
 433   // point when all the tasks complete their work. It is really used
 434   // to determine the points between the end of concurrent marking and
 435   // time of remark.
 436   volatile bool           _concurrent_marking_in_progress;
 437 
 438   // verbose level
 439   CMVerboseLevel          _verbose_level;
 440 
 441   // All of these times are in ms.
 442   NumberSeq _init_times;
 443   NumberSeq _remark_times;
 444   NumberSeq   _remark_mark_times;
 445   NumberSeq   _remark_weak_ref_times;
 446   NumberSeq _cleanup_times;
 447   double    _total_counting_time;
 448   double    _total_rs_scrub_time;
 449 
 450   double*   _accum_task_vtime;   // accumulated task vtime
 451 
 452   FlexibleWorkGang* _parallel_workers;
 453 
 454   ForceOverflowSettings _force_overflow_conc;
 455   ForceOverflowSettings _force_overflow_stw;
 456 
 457   void weakRefsWork(bool clear_all_soft_refs);
 458 
 459   void swapMarkBitMaps();
 460 
 461   // It resets the global marking data structures, as well as the
 462   // task local ones; should be called during initial mark.
 463   void reset();
 464   // It resets all the marking data structures.
 465   void clear_marking_state(bool clear_overflow = true);
 466 
 467   // It should be called to indicate which phase we're in (concurrent
 468   // mark or remark) and how many threads are currently active.
 469   void set_phase(uint active_tasks, bool concurrent);
 470   // We do this after we're done with marking so that the marking data
 471   // structures are initialised to a sensible and predictable state.
 472   void set_non_marking_state();
 473 
 474   // prints all gathered CM-related statistics
 475   void print_stats();
 476 
 477   bool cleanup_list_is_empty() {
 478     return _cleanup_list.is_empty();
 479   }
 480 
 481   // accessor methods
 482   uint parallel_marking_threads() { return _parallel_marking_threads; }
 483   uint max_parallel_marking_threads() { return _max_parallel_marking_threads;}
 484   double sleep_factor()             { return _sleep_factor; }
 485   double marking_task_overhead()    { return _marking_task_overhead;}
 486   double cleanup_sleep_factor()     { return _cleanup_sleep_factor; }
 487   double cleanup_task_overhead()    { return _cleanup_task_overhead;}
 488 
 489   HeapWord*               finger()        { return _finger;   }
 490   bool                    concurrent()    { return _concurrent; }
 491   uint                    active_tasks()  { return _active_tasks; }
 492   ParallelTaskTerminator* terminator()    { return &_terminator; }
 493 
 494   // It claims the next available region to be scanned by a marking
 495   // task. It might return NULL if the next region is empty or we have
 496   // run out of regions. In the latter case, out_of_regions()
 497   // determines whether we've really run out of regions or the task
 498   // should call claim_region() again.  This might seem a bit
 499   // awkward. Originally, the code was written so that claim_region()
 500   // either successfully returned with a non-empty region or there
 501   // were no more regions to be claimed. The problem with this was
 502   // that, in certain circumstances, it iterated over large chunks of
 503   // the heap finding only empty regions and, while it was working, it
 504   // was preventing the calling task to call its regular clock
 505   // method. So, this way, each task will spend very little time in
 506   // claim_region() and is allowed to call the regular clock method
 507   // frequently.
 508   HeapRegion* claim_region(int task);
 509 
 510   // It determines whether we've run out of regions to scan.
 511   bool        out_of_regions() { return _finger == _heap_end; }
 512 
 513   // Returns the task with the given id
 514   CMTask* task(int id) {
 515     assert(0 <= id && id < (int) _active_tasks,
 516            "task id not within active bounds");
 517     return _tasks[id];
 518   }
 519 
 520   // Returns the task queue with the given id
 521   CMTaskQueue* task_queue(int id) {
 522     assert(0 <= id && id < (int) _active_tasks,
 523            "task queue id not within active bounds");
 524     return (CMTaskQueue*) _task_queues->queue(id);
 525   }
 526 
 527   // Returns the task queue set
 528   CMTaskQueueSet* task_queues()  { return _task_queues; }
 529 
 530   // Access / manipulation of the overflow flag which is set to
 531   // indicate that the global stack has overflown
 532   bool has_overflown()           { return _has_overflown; }
 533   void set_has_overflown()       { _has_overflown = true; }
 534   void clear_has_overflown()     { _has_overflown = false; }
 535   bool restart_for_overflow()    { return _restart_for_overflow; }
 536 
 537   bool has_aborted()             { return _has_aborted; }
 538 
 539   // Methods to enter the two overflow sync barriers
 540   void enter_first_sync_barrier(int task_num);
 541   void enter_second_sync_barrier(int task_num);
 542 
 543   ForceOverflowSettings* force_overflow_conc() {
 544     return &_force_overflow_conc;
 545   }
 546 
 547   ForceOverflowSettings* force_overflow_stw() {
 548     return &_force_overflow_stw;
 549   }
 550 
 551   ForceOverflowSettings* force_overflow() {
 552     if (concurrent()) {
 553       return force_overflow_conc();
 554     } else {
 555       return force_overflow_stw();
 556     }
 557   }
 558 
 559   // Live Data Counting data structures...
 560   // These data structures are initialized at the start of
 561   // marking. They are written to while marking is active.
 562   // They are aggregated during remark; the aggregated values
 563   // are then used to populate the _region_bm, _card_bm, and
 564   // the total live bytes, which are then subsequently updated
 565   // during cleanup.
 566 
 567   // An array of bitmaps (one bit map per task). Each bitmap
 568   // is used to record the cards spanned by the live objects
 569   // marked by that task/worker.
 570   BitMap*  _count_card_bitmaps;
 571 
 572   // Used to record the number of marked live bytes
 573   // (for each region, by worker thread).
 574   size_t** _count_marked_bytes;
 575 
 576   // Card index of the bottom of the G1 heap. Used for biasing indices into
 577   // the card bitmaps.
 578   intptr_t _heap_bottom_card_num;
 579 
 580 public:
 581   // Manipulation of the global mark stack.
 582   // Notice that the first mark_stack_push is CAS-based, whereas the
 583   // two below are Mutex-based. This is OK since the first one is only
 584   // called during evacuation pauses and doesn't compete with the
 585   // other two (which are called by the marking tasks during
 586   // concurrent marking or remark).
 587   bool mark_stack_push(oop p) {
 588     _markStack.par_push(p);
 589     if (_markStack.overflow()) {
 590       set_has_overflown();
 591       return false;
 592     }
 593     return true;
 594   }
 595   bool mark_stack_push(oop* arr, int n) {
 596     _markStack.par_push_arr(arr, n);
 597     if (_markStack.overflow()) {
 598       set_has_overflown();
 599       return false;
 600     }
 601     return true;
 602   }
 603   void mark_stack_pop(oop* arr, int max, int* n) {
 604     _markStack.par_pop_arr(arr, max, n);
 605   }
 606   size_t mark_stack_size()                { return _markStack.size(); }
 607   size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
 608   bool mark_stack_overflow()              { return _markStack.overflow(); }
 609   bool mark_stack_empty()                 { return _markStack.isEmpty(); }
 610 
 611   CMRootRegions* root_regions() { return &_root_regions; }
 612 
 613   bool concurrent_marking_in_progress() {
 614     return _concurrent_marking_in_progress;
 615   }
 616   void set_concurrent_marking_in_progress() {
 617     _concurrent_marking_in_progress = true;
 618   }
 619   void clear_concurrent_marking_in_progress() {
 620     _concurrent_marking_in_progress = false;
 621   }
 622 
 623   void update_accum_task_vtime(int i, double vtime) {
 624     _accum_task_vtime[i] += vtime;
 625   }
 626 
 627   double all_task_accum_vtime() {
 628     double ret = 0.0;
 629     for (int i = 0; i < (int)_max_task_num; ++i)
 630       ret += _accum_task_vtime[i];
 631     return ret;
 632   }
 633 
 634   // Attempts to steal an object from the task queues of other tasks
 635   bool try_stealing(int task_num, int* hash_seed, oop& obj) {
 636     return _task_queues->steal(task_num, hash_seed, obj);
 637   }
 638 
 639   ConcurrentMark(ReservedSpace rs, uint max_regions);
 640   ~ConcurrentMark();
 641 
 642   ConcurrentMarkThread* cmThread() { return _cmThread; }
 643 
 644   CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
 645   CMBitMap*   nextMarkBitMap() const { return _nextMarkBitMap; }
 646 
 647   // Returns the number of GC threads to be used in a concurrent
 648   // phase based on the number of GC threads being used in a STW
 649   // phase.
 650   uint scale_parallel_threads(uint n_par_threads);
 651 
 652   // Calculates the number of GC threads to be used in a concurrent phase.
 653   uint calc_parallel_marking_threads();
 654 
 655   // The following three are interaction between CM and
 656   // G1CollectedHeap
 657 
 658   // This notifies CM that a root during initial-mark needs to be
 659   // grayed. It is MT-safe. word_size is the size of the object in
 660   // words. It is passed explicitly as sometimes we cannot calculate
 661   // it from the given object because it might be in an inconsistent
 662   // state (e.g., in to-space and being copied). So the caller is
 663   // responsible for dealing with this issue (e.g., get the size from
 664   // the from-space image when the to-space image might be
 665   // inconsistent) and always passing the size. hr is the region that
 666   // contains the object and it's passed optionally from callers who
 667   // might already have it (no point in recalculating it).
 668   inline void grayRoot(oop obj, size_t word_size,
 669                        uint worker_id, HeapRegion* hr = NULL);
 670 
 671   // It iterates over the heap and for each object it comes across it
 672   // will dump the contents of its reference fields, as well as
 673   // liveness information for the object and its referents. The dump
 674   // will be written to a file with the following name:
 675   // G1PrintReachableBaseFile + "." + str.
 676   // vo decides whether the prev (vo == UsePrevMarking), the next
 677   // (vo == UseNextMarking) marking information, or the mark word
 678   // (vo == UseMarkWord) will be used to determine the liveness of
 679   // each object / referent.
 680   // If all is true, all objects in the heap will be dumped, otherwise
 681   // only the live ones. In the dump the following symbols / breviations
 682   // are used:
 683   //   M : an explicitly live object (its bitmap bit is set)
 684   //   > : an implicitly live object (over tams)
 685   //   O : an object outside the G1 heap (typically: in the perm gen)
 686   //   NOT : a reference field whose referent is not live
 687   //   AND MARKED : indicates that an object is both explicitly and
 688   //   implicitly live (it should be one or the other, not both)
 689   void print_reachable(const char* str,
 690                        VerifyOption vo, bool all) PRODUCT_RETURN;
 691 
 692   // Clear the next marking bitmap (will be called concurrently).
 693   void clearNextBitmap();
 694 
 695   // These two do the work that needs to be done before and after the
 696   // initial root checkpoint. Since this checkpoint can be done at two
 697   // different points (i.e. an explicit pause or piggy-backed on a
 698   // young collection), then it's nice to be able to easily share the
 699   // pre/post code. It might be the case that we can put everything in
 700   // the post method. TP
 701   void checkpointRootsInitialPre();
 702   void checkpointRootsInitialPost();
 703 
 704   // Scan all the root regions and mark everything reachable from
 705   // them.
 706   void scanRootRegions();
 707 
 708   // Scan a single root region and mark everything reachable from it.
 709   void scanRootRegion(HeapRegion* hr, uint worker_id);
 710 
 711   // Do concurrent phase of marking, to a tentative transitive closure.
 712   void markFromRoots();
 713 
 714   void checkpointRootsFinal(bool clear_all_soft_refs);
 715   void checkpointRootsFinalWork();
 716   void cleanup();
 717   void completeCleanup();
 718 
 719   // Mark in the previous bitmap.  NB: this is usually read-only, so use
 720   // this carefully!
 721   inline void markPrev(oop p);
 722 
 723   // Clears marks for all objects in the given range, for the prev,
 724   // next, or both bitmaps.  NB: the previous bitmap is usually
 725   // read-only, so use this carefully!
 726   void clearRangePrevBitmap(MemRegion mr);
 727   void clearRangeNextBitmap(MemRegion mr);
 728   void clearRangeBothBitmaps(MemRegion mr);
 729 
 730   // Notify data structures that a GC has started.
 731   void note_start_of_gc() {
 732     _markStack.note_start_of_gc();
 733   }
 734 
 735   // Notify data structures that a GC is finished.
 736   void note_end_of_gc() {
 737     _markStack.note_end_of_gc();
 738   }
 739 
 740   // Verify that there are no CSet oops on the stacks (taskqueues /
 741   // global mark stack), enqueued SATB buffers, per-thread SATB
 742   // buffers, and fingers (global / per-task). The boolean parameters
 743   // decide which of the above data structures to verify. If marking
 744   // is not in progress, it's a no-op.
 745   void verify_no_cset_oops(bool verify_stacks,
 746                            bool verify_enqueued_buffers,
 747                            bool verify_thread_buffers,
 748                            bool verify_fingers) PRODUCT_RETURN;
 749 
 750   // It is called at the end of an evacuation pause during marking so
 751   // that CM is notified of where the new end of the heap is. It
 752   // doesn't do anything if concurrent_marking_in_progress() is false,
 753   // unless the force parameter is true.
 754   void update_g1_committed(bool force = false);
 755 
 756   bool isMarked(oop p) const {
 757     assert(p != NULL && p->is_oop(), "expected an oop");
 758     HeapWord* addr = (HeapWord*)p;
 759     assert(addr >= _nextMarkBitMap->startWord() ||
 760            addr < _nextMarkBitMap->endWord(), "in a region");
 761 
 762     return _nextMarkBitMap->isMarked(addr);
 763   }
 764 
 765   inline bool not_yet_marked(oop p) const;
 766 
 767   // XXX Debug code
 768   bool containing_card_is_marked(void* p);
 769   bool containing_cards_are_marked(void* start, void* last);
 770 
 771   bool isPrevMarked(oop p) const {
 772     assert(p != NULL && p->is_oop(), "expected an oop");
 773     HeapWord* addr = (HeapWord*)p;
 774     assert(addr >= _prevMarkBitMap->startWord() ||
 775            addr < _prevMarkBitMap->endWord(), "in a region");
 776 
 777     return _prevMarkBitMap->isMarked(addr);
 778   }
 779 
 780   inline bool do_yield_check(uint worker_i = 0);
 781   inline bool should_yield();
 782 
 783   // Called to abort the marking cycle after a Full GC takes palce.
 784   void abort();
 785 
 786   // This prints the global/local fingers. It is used for debugging.
 787   NOT_PRODUCT(void print_finger();)
 788 
 789   void print_summary_info();
 790 
 791   void print_worker_threads_on(outputStream* st) const;
 792 
 793   // The following indicate whether a given verbose level has been
 794   // set. Notice that anything above stats is conditional to
 795   // _MARKING_VERBOSE_ having been set to 1
 796   bool verbose_stats() {
 797     return _verbose_level >= stats_verbose;
 798   }
 799   bool verbose_low() {
 800     return _MARKING_VERBOSE_ && _verbose_level >= low_verbose;
 801   }
 802   bool verbose_medium() {
 803     return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose;
 804   }
 805   bool verbose_high() {
 806     return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
 807   }
 808 
 809   // Counting data structure accessors







 810 
 811   // Returns the card number of the bottom of the G1 heap.
 812   // Used in biasing indices into accounting card bitmaps.
 813   intptr_t heap_bottom_card_num() const {
 814     return _heap_bottom_card_num;
 815   }
 816 
 817   // Returns the card bitmap for a given task or worker id.
 818   BitMap* count_card_bitmap_for(uint worker_id) {
 819     assert(0 <= worker_id && worker_id < _max_task_num, "oob");
 820     assert(_count_card_bitmaps != NULL, "uninitialized");
 821     BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
 822     assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
 823     return task_card_bm;
 824   }
 825 
 826   // Returns the array containing the marked bytes for each region,
 827   // for the given worker or task id.
 828   size_t* count_marked_bytes_array_for(uint worker_id) {
 829     assert(0 <= worker_id && worker_id < _max_task_num, "oob");
 830     assert(_count_marked_bytes != NULL, "uninitialized");
 831     size_t* marked_bytes_array = _count_marked_bytes[worker_id];
 832     assert(marked_bytes_array != NULL, "uninitialized");
 833     return marked_bytes_array;
 834   }
 835 
 836   // Returns the index in the liveness accounting card table bitmap
 837   // for the given address
 838   inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
 839 
 840   // Counts the size of the given memory region in the the given
 841   // marked_bytes array slot for the given HeapRegion.
 842   // Sets the bits in the given card bitmap that are associated with the
 843   // cards that are spanned by the memory region.
 844   inline void count_region(MemRegion mr, HeapRegion* hr,
 845                            size_t* marked_bytes_array,
 846                            BitMap* task_card_bm);
 847 
 848   // Counts the given memory region in the task/worker counting
 849   // data structures for the given worker id.
 850   inline void count_region(MemRegion mr, HeapRegion* hr, uint worker_id);
 851 
 852   // Counts the given memory region in the task/worker counting
 853   // data structures for the given worker id.
 854   inline void count_region(MemRegion mr, uint worker_id);
 855 
 856   // Counts the given object in the given task/worker counting
 857   // data structures.
 858   inline void count_object(oop obj, HeapRegion* hr,
 859                            size_t* marked_bytes_array,
 860                            BitMap* task_card_bm);
 861 
 862   // Counts the given object in the task/worker counting data
 863   // structures for the given worker id.
 864   inline void count_object(oop obj, HeapRegion* hr, uint worker_id);
 865 
 866   // Attempts to mark the given object and, if successful, counts
 867   // the object in the given task/worker counting structures.
 868   inline bool par_mark_and_count(oop obj, HeapRegion* hr,
 869                                  size_t* marked_bytes_array,
 870                                  BitMap* task_card_bm);
 871 
 872   // Attempts to mark the given object and, if successful, counts
 873   // the object in the task/worker counting structures for the
 874   // given worker id.
 875   inline bool par_mark_and_count(oop obj, size_t word_size,
 876                                  HeapRegion* hr, uint worker_id);
 877 
 878   // Attempts to mark the given object and, if successful, counts
 879   // the object in the task/worker counting structures for the
 880   // given worker id.
 881   inline bool par_mark_and_count(oop obj, HeapRegion* hr, uint worker_id);
 882 
 883   // Similar to the above routine but we don't know the heap region that
 884   // contains the object to be marked/counted, which this routine looks up.
 885   inline bool par_mark_and_count(oop obj, uint worker_id);
 886 
 887   // Similar to the above routine but there are times when we cannot
 888   // safely calculate the size of obj due to races and we, therefore,
 889   // pass the size in as a parameter. It is the caller's reponsibility
 890   // to ensure that the size passed in for obj is valid.
 891   inline bool par_mark_and_count(oop obj, size_t word_size, uint worker_id);
 892 
 893   // Unconditionally mark the given object, and unconditinally count
 894   // the object in the counting structures for worker id 0.
 895   // Should *not* be called from parallel code.
 896   inline bool mark_and_count(oop obj, HeapRegion* hr);
 897 
 898   // Similar to the above routine but we don't know the heap region that
 899   // contains the object to be marked/counted, which this routine looks up.
 900   // Should *not* be called from parallel code.
 901   inline bool mark_and_count(oop obj);
 902 
 903 protected:
 904   // Clear all the per-task bitmaps and arrays used to store the
 905   // counting data.
 906   void clear_all_count_data();
 907 
 908   // Aggregates the counting data for each worker/task
 909   // that was constructed while marking. Also sets
 910   // the amount of marked bytes for each region and
 911   // the top at concurrent mark count.
 912   void aggregate_count_data();
 913 
 914   // Verification routine
 915   void verify_count_data();
 916 };
 917 
 918 // A class representing a marking task.
 919 class CMTask : public TerminatorTerminator {
 920 private:
 921   enum PrivateConstants {
 922     // the regular clock call is called once the scanned words reaches
 923     // this limit
 924     words_scanned_period          = 12*1024,
 925     // the regular clock call is called once the number of visited
 926     // references reaches this limit
 927     refs_reached_period           = 384,
 928     // initial value for the hash seed, used in the work stealing code
 929     init_hash_seed                = 17,
 930     // how many entries will be transferred between global stack and
 931     // local queues
 932     global_stack_transfer_size    = 16
 933   };
 934 
 935   int                         _task_id;
 936   G1CollectedHeap*            _g1h;
 937   ConcurrentMark*             _cm;
 938   CMBitMap*                   _nextMarkBitMap;
 939   // the task queue of this task
 940   CMTaskQueue*                _task_queue;
 941 private:
 942   // the task queue set---needed for stealing
 943   CMTaskQueueSet*             _task_queues;
 944   // indicates whether the task has been claimed---this is only  for
 945   // debugging purposes
 946   bool                        _claimed;
 947 
 948   // number of calls to this task
 949   int                         _calls;
 950 
 951   // when the virtual timer reaches this time, the marking step should
 952   // exit
 953   double                      _time_target_ms;
 954   // the start time of the current marking step
 955   double                      _start_time_ms;
 956 
 957   // the oop closure used for iterations over oops
 958   G1CMOopClosure*             _cm_oop_closure;
 959 
 960   // the region this task is scanning, NULL if we're not scanning any
 961   HeapRegion*                 _curr_region;
 962   // the local finger of this task, NULL if we're not scanning a region
 963   HeapWord*                   _finger;
 964   // limit of the region this task is scanning, NULL if we're not scanning one
 965   HeapWord*                   _region_limit;
 966 
 967   // the number of words this task has scanned
 968   size_t                      _words_scanned;
 969   // When _words_scanned reaches this limit, the regular clock is
 970   // called. Notice that this might be decreased under certain
 971   // circumstances (i.e. when we believe that we did an expensive
 972   // operation).
 973   size_t                      _words_scanned_limit;
 974   // the initial value of _words_scanned_limit (i.e. what it was
 975   // before it was decreased).
 976   size_t                      _real_words_scanned_limit;
 977 
 978   // the number of references this task has visited
 979   size_t                      _refs_reached;
 980   // When _refs_reached reaches this limit, the regular clock is
 981   // called. Notice this this might be decreased under certain
 982   // circumstances (i.e. when we believe that we did an expensive
 983   // operation).
 984   size_t                      _refs_reached_limit;
 985   // the initial value of _refs_reached_limit (i.e. what it was before
 986   // it was decreased).
 987   size_t                      _real_refs_reached_limit;
 988 
 989   // used by the work stealing stuff
 990   int                         _hash_seed;
 991   // if this is true, then the task has aborted for some reason
 992   bool                        _has_aborted;
 993   // set when the task aborts because it has met its time quota
 994   bool                        _has_timed_out;
 995   // true when we're draining SATB buffers; this avoids the task
 996   // aborting due to SATB buffers being available (as we're already
 997   // dealing with them)
 998   bool                        _draining_satb_buffers;
 999 
1000   // number sequence of past step times
1001   NumberSeq                   _step_times_ms;
1002   // elapsed time of this task
1003   double                      _elapsed_time_ms;
1004   // termination time of this task
1005   double                      _termination_time_ms;
1006   // when this task got into the termination protocol
1007   double                      _termination_start_time_ms;
1008 
1009   // true when the task is during a concurrent phase, false when it is
1010   // in the remark phase (so, in the latter case, we do not have to
1011   // check all the things that we have to check during the concurrent
1012   // phase, i.e. SATB buffer availability...)
1013   bool                        _concurrent;
1014 
1015   TruncatedSeq                _marking_step_diffs_ms;
1016 
1017   // Counting data structures. Embedding the task's marked_bytes_array
1018   // and card bitmap into the actual task saves having to go through
1019   // the ConcurrentMark object.
1020   size_t*                     _marked_bytes_array;
1021   BitMap*                     _card_bm;
1022 
1023   // LOTS of statistics related with this task
1024 #if _MARKING_STATS_
1025   NumberSeq                   _all_clock_intervals_ms;
1026   double                      _interval_start_time_ms;
1027 
1028   int                         _aborted;
1029   int                         _aborted_overflow;
1030   int                         _aborted_cm_aborted;
1031   int                         _aborted_yield;
1032   int                         _aborted_timed_out;
1033   int                         _aborted_satb;
1034   int                         _aborted_termination;
1035 
1036   int                         _steal_attempts;
1037   int                         _steals;
1038 
1039   int                         _clock_due_to_marking;
1040   int                         _clock_due_to_scanning;
1041 
1042   int                         _local_pushes;
1043   int                         _local_pops;
1044   int                         _local_max_size;
1045   int                         _objs_scanned;
1046 
1047   int                         _global_pushes;
1048   int                         _global_pops;
1049   int                         _global_max_size;
1050 
1051   int                         _global_transfers_to;
1052   int                         _global_transfers_from;
1053 
1054   int                         _regions_claimed;
1055   int                         _objs_found_on_bitmap;
1056 
1057   int                         _satb_buffers_processed;
1058 #endif // _MARKING_STATS_
1059 
1060   // it updates the local fields after this task has claimed
1061   // a new region to scan
1062   void setup_for_region(HeapRegion* hr);
1063   // it brings up-to-date the limit of the region
1064   void update_region_limit();
1065 
1066   // called when either the words scanned or the refs visited limit
1067   // has been reached
1068   void reached_limit();
1069   // recalculates the words scanned and refs visited limits
1070   void recalculate_limits();
1071   // decreases the words scanned and refs visited limits when we reach
1072   // an expensive operation
1073   void decrease_limits();
1074   // it checks whether the words scanned or refs visited reached their
1075   // respective limit and calls reached_limit() if they have
1076   void check_limits() {
1077     if (_words_scanned >= _words_scanned_limit ||
1078         _refs_reached >= _refs_reached_limit) {
1079       reached_limit();
1080     }
1081   }
1082   // this is supposed to be called regularly during a marking step as
1083   // it checks a bunch of conditions that might cause the marking step
1084   // to abort
1085   void regular_clock_call();
1086   bool concurrent() { return _concurrent; }
1087 
1088 public:
1089   // It resets the task; it should be called right at the beginning of
1090   // a marking phase.
1091   void reset(CMBitMap* _nextMarkBitMap);
1092   // it clears all the fields that correspond to a claimed region.
1093   void clear_region_fields();
1094 
1095   void set_concurrent(bool concurrent) { _concurrent = concurrent; }
1096 
1097   // The main method of this class which performs a marking step
1098   // trying not to exceed the given duration. However, it might exit
1099   // prematurely, according to some conditions (i.e. SATB buffers are
1100   // available for processing).
1101   void do_marking_step(double target_ms, bool do_stealing, bool do_termination);
1102 
1103   // These two calls start and stop the timer
1104   void record_start_time() {
1105     _elapsed_time_ms = os::elapsedTime() * 1000.0;
1106   }
1107   void record_end_time() {
1108     _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
1109   }
1110 
1111   // returns the task ID
1112   int task_id() { return _task_id; }
1113 
1114   // From TerminatorTerminator. It determines whether this task should
1115   // exit the termination protocol after it's entered it.
1116   virtual bool should_exit_termination();
1117 
1118   // Resets the local region fields after a task has finished scanning a
1119   // region; or when they have become stale as a result of the region
1120   // being evacuated.
1121   void giveup_current_region();
1122 
1123   HeapWord* finger()            { return _finger; }
1124 
1125   bool has_aborted()            { return _has_aborted; }
1126   void set_has_aborted()        { _has_aborted = true; }
1127   void clear_has_aborted()      { _has_aborted = false; }
1128   bool has_timed_out()          { return _has_timed_out; }
1129   bool claimed()                { return _claimed; }
1130 
1131   void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
1132 
1133   // It grays the object by marking it and, if necessary, pushing it
1134   // on the local queue
1135   inline void deal_with_reference(oop obj);
1136 
1137   // It scans an object and visits its children.
1138   void scan_object(oop obj);
1139 
1140   // It pushes an object on the local queue.
1141   inline void push(oop obj);
1142 
1143   // These two move entries to/from the global stack.
1144   void move_entries_to_global_stack();
1145   void get_entries_from_global_stack();
1146 
1147   // It pops and scans objects from the local queue. If partially is
1148   // true, then it stops when the queue size is of a given limit. If
1149   // partially is false, then it stops when the queue is empty.
1150   void drain_local_queue(bool partially);
1151   // It moves entries from the global stack to the local queue and
1152   // drains the local queue. If partially is true, then it stops when
1153   // both the global stack and the local queue reach a given size. If
1154   // partially if false, it tries to empty them totally.
1155   void drain_global_stack(bool partially);
1156   // It keeps picking SATB buffers and processing them until no SATB
1157   // buffers are available.
1158   void drain_satb_buffers();
1159 
1160   // moves the local finger to a new location
1161   inline void move_finger_to(HeapWord* new_finger) {
1162     assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
1163     _finger = new_finger;
1164   }
1165 
1166   CMTask(int task_num, ConcurrentMark *cm,
1167          size_t* marked_bytes, BitMap* card_bm,
1168          CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
1169 
1170   // it prints statistics associated with this task
1171   void print_stats();
1172 
1173 #if _MARKING_STATS_
1174   void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
1175 #endif // _MARKING_STATS_
1176 };
1177 
1178 // Class that's used to to print out per-region liveness
1179 // information. It's currently used at the end of marking and also
1180 // after we sort the old regions at the end of the cleanup operation.
1181 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
1182 private:
1183   outputStream* _out;
1184 
1185   // Accumulators for these values.
1186   size_t _total_used_bytes;
1187   size_t _total_capacity_bytes;
1188   size_t _total_prev_live_bytes;
1189   size_t _total_next_live_bytes;
1190 
1191   // These are set up when we come across a "stars humongous" region
1192   // (as this is where most of this information is stored, not in the
1193   // subsequent "continues humongous" regions). After that, for every
1194   // region in a given humongous region series we deduce the right
1195   // values for it by simply subtracting the appropriate amount from
1196   // these fields. All these values should reach 0 after we've visited
1197   // the last region in the series.
1198   size_t _hum_used_bytes;
1199   size_t _hum_capacity_bytes;
1200   size_t _hum_prev_live_bytes;
1201   size_t _hum_next_live_bytes;
1202 
1203   static double perc(size_t val, size_t total) {
1204     if (total == 0) {
1205       return 0.0;
1206     } else {
1207       return 100.0 * ((double) val / (double) total);
1208     }
1209   }
1210 
1211   static double bytes_to_mb(size_t val) {
1212     return (double) val / (double) M;
1213   }
1214 
1215   // See the .cpp file.
1216   size_t get_hum_bytes(size_t* hum_bytes);
1217   void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes,
1218                      size_t* prev_live_bytes, size_t* next_live_bytes);
1219 
1220 public:
1221   // The header and footer are printed in the constructor and
1222   // destructor respectively.
1223   G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name);
1224   virtual bool doHeapRegion(HeapRegion* r);
1225   ~G1PrintRegionLivenessInfoClosure();
1226 };
1227 
1228 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
--- EOF ---