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

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 *

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP

#include "gc_implementation/g1/heapRegionSets.hpp"

#include "utilities/taskqueue.hpp"

class G1CollectedHeap;

class CMTask;

typedef GenericTaskQueue<oop, mtGC>            CMTaskQueue;

typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;

// Closure used by CM during concurrent reference discovery

// and reference processing (during remarking) to determine

// if a particular object is alive. It is primarily used

// to determine if referents of discovered reference objects

// are alive. An instance is also embedded into the

// reference processor as the _is_alive_non_header field

class G1CMIsAliveClosure: public BoolObjectClosure {

  G1CollectedHeap* _g1;

 public:

  G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }

  void do_object(oop obj) {

    ShouldNotCallThis();

  }

  bool do_object_b(oop obj);

};

// A generic CM bit map.  This is essentially a wrapper around the BitMap

// class, with one bit per (1<<_shifter) HeapWords.

class CMBitMapRO VALUE_OBJ_CLASS_SPEC {

 protected:

  HeapWord* _bmStartWord;      // base address of range covered by map

  size_t    _bmWordSize;       // map size (in #HeapWords covered)

  const int _shifter;          // map to char or bit

  VirtualSpace _virtual_space; // underlying the bit map

  BitMap    _bm;               // the bit map itself

 public:

  // constructor

  CMBitMapRO(int shifter);

  enum { do_yield = true };

  // inquiries

  HeapWord* startWord()   const { return _bmStartWord; }

  size_t    sizeInWords() const { return _bmWordSize;  }

  // the following is one past the last word in space

  HeapWord* endWord()     const { return _bmStartWord + _bmWordSize; }

  // read marks

  bool isMarked(HeapWord* addr) const {

    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),

           "outside underlying space?");

    return _bm.at(heapWordToOffset(addr));

  }

  // iteration

  inline bool iterate(BitMapClosure* cl, MemRegion mr);

  inline bool iterate(BitMapClosure* cl);

  // Return the address corresponding to the next marked bit at or after

  // "addr", and before "limit", if "limit" is non-NULL.  If there is no

  // such bit, returns "limit" if that is non-NULL, or else "endWord()".

  HeapWord* getNextMarkedWordAddress(HeapWord* addr,

                                     HeapWord* limit = NULL) const;

  // Return the address corresponding to the next unmarked bit at or after

  // "addr", and before "limit", if "limit" is non-NULL.  If there is no

  // such bit, returns "limit" if that is non-NULL, or else "endWord()".

  HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,

                                       HeapWord* limit = NULL) const;

  // conversion utilities

  HeapWord* offsetToHeapWord(size_t offset) const {

    return _bmStartWord + (offset << _shifter);

  }

  size_t heapWordToOffset(HeapWord* addr) const {

    return pointer_delta(addr, _bmStartWord) >> _shifter;

  }

  int heapWordDiffToOffsetDiff(size_t diff) const;

  // The argument addr should be the start address of a valid object

  HeapWord* nextObject(HeapWord* addr) {

    oop obj = (oop) addr;

    HeapWord* res =  addr + obj->size();

    assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");

    return res;

  }

  void print_on_error(outputStream* st, const char* prefix) const;

  // debugging

  NOT_PRODUCT(bool covers(ReservedSpace rs) const;)

};

class CMBitMap : public CMBitMapRO {

 public:

  // constructor

  CMBitMap(int shifter) :

    CMBitMapRO(shifter) {}

  // Allocates the back store for the marking bitmap

  bool allocate(ReservedSpace heap_rs);

  // write marks

  void mark(HeapWord* addr) {

    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),

           "outside underlying space?");

    _bm.set_bit(heapWordToOffset(addr));

  }

  void clear(HeapWord* addr) {

    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),

           "outside underlying space?");

    _bm.clear_bit(heapWordToOffset(addr));

  }

  bool parMark(HeapWord* addr) {

    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),

           "outside underlying space?");

    return _bm.par_set_bit(heapWordToOffset(addr));

  }

  bool parClear(HeapWord* addr) {

    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),

           "outside underlying space?");

    return _bm.par_clear_bit(heapWordToOffset(addr));

  }

  void markRange(MemRegion mr);

  void clearAll();

  void clearRange(MemRegion mr);

  // Starting at the bit corresponding to "addr" (inclusive), find the next

  // "1" bit, if any.  This bit starts some run of consecutive "1"'s; find

  // the end of this run (stopping at "end_addr").  Return the MemRegion

  // covering from the start of the region corresponding to the first bit

  // of the run to the end of the region corresponding to the last bit of

  // the run.  If there is no "1" bit at or after "addr", return an empty

  // MemRegion.

  MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);

};

// Represents a marking stack used by ConcurrentMarking in the G1 collector.

class CMMarkStack VALUE_OBJ_CLASS_SPEC {

  VirtualSpace _virtual_space;   // Underlying backing store for actual stack

  ConcurrentMark* _cm;

  oop* _base;        // bottom of stack

  jint _index;       // one more than last occupied index

  jint _capacity;    // max #elements

  jint _saved_index; // value of _index saved at start of GC

  NOT_PRODUCT(jint _max_depth;)   // max depth plumbed during run

  bool  _overflow;

  bool  _should_expand;

  DEBUG_ONLY(bool _drain_in_progress;)

  DEBUG_ONLY(bool _drain_in_progress_yields;)

 public:

  CMMarkStack(ConcurrentMark* cm);

  ~CMMarkStack();

#ifndef PRODUCT

  jint max_depth() const {

    return _max_depth;

  }

#endif

  bool allocate(size_t capacity);

  oop pop() {

    if (!isEmpty()) {

      return _base[--_index] ;

    }

    return NULL;

  }

  // If overflow happens, don't do the push, and record the overflow.

  // *Requires* that "ptr" is already marked.

  void push(oop ptr) {

    if (isFull()) {

      // Record overflow.

      _overflow = true;

      return;

    } else {

      _base[_index++] = ptr;

      NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));

    }

  }

  // Non-block impl.  Note: concurrency is allowed only with other

  // "par_push" operations, not with "pop" or "drain".  We would need

  // parallel versions of them if such concurrency was desired.

  void par_push(oop ptr);

  // Pushes the first "n" elements of "ptr_arr" on the stack.

  // Non-block impl.  Note: concurrency is allowed only with other

  // "par_adjoin_arr" or "push" operations, not with "pop" or "drain".

  void par_adjoin_arr(oop* ptr_arr, int n);

  // Pushes the first "n" elements of "ptr_arr" on the stack.

  // Locking impl: concurrency is allowed only with

  // "par_push_arr" and/or "par_pop_arr" operations, which use the same

  // locking strategy.

  void par_push_arr(oop* ptr_arr, int n);

  // If returns false, the array was empty.  Otherwise, removes up to "max"

  // elements from the stack, and transfers them to "ptr_arr" in an

  // unspecified order.  The actual number transferred is given in "n" ("n

  // == 0" is deliberately redundant with the return value.)  Locking impl:

  // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"

  // operations, which use the same locking strategy.

  bool par_pop_arr(oop* ptr_arr, int max, int* n);

  // Drain the mark stack, applying the given closure to all fields of

  // objects on the stack.  (That is, continue until the stack is empty,

  // even if closure applications add entries to the stack.)  The "bm"

  // argument, if non-null, may be used to verify that only marked objects

  // are on the mark stack.  If "yield_after" is "true", then the

  // concurrent marker performing the drain offers to yield after

  // processing each object.  If a yield occurs, stops the drain operation

  // and returns false.  Otherwise, returns true.

  template<class OopClosureClass>

  bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);

  bool isEmpty()    { return _index == 0; }

  bool isFull()     { return _index == _capacity; }

  int  maxElems()   { return _capacity; }

  bool overflow() { return _overflow; }

  void clear_overflow() { _overflow = false; }

  bool should_expand() const { return _should_expand; }

  void set_should_expand();

  // Expand the stack, typically in response to an overflow condition

  void expand();

  int  size() { return _index; }

  void setEmpty()   { _index = 0; clear_overflow(); }

  // Record the current index.

  void note_start_of_gc();

  // Make sure that we have not added any entries to the stack during GC.

  void note_end_of_gc();

  // iterate over the oops in the mark stack, up to the bound recorded via

  // the call above.

  void oops_do(OopClosure* f);

};

class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {

private:

#ifndef PRODUCT

  uintx _num_remaining;

  bool _force;

#endif // !defined(PRODUCT)

public:

  void init() PRODUCT_RETURN;

  void update() PRODUCT_RETURN;

  bool should_force() PRODUCT_RETURN_( return false; );

};

// this will enable a variety of different statistics per GC task

#define _MARKING_STATS_       0

// this will enable the higher verbose levels

#define _MARKING_VERBOSE_     0

#if _MARKING_STATS_

#define statsOnly(statement)  \

do {                          \

  statement ;                 \

} while (0)

#else // _MARKING_STATS_

#define statsOnly(statement)  \

do {                          \

} while (0)

#endif // _MARKING_STATS_

typedef enum {

  no_verbose  = 0,   // verbose turned off

  stats_verbose,     // only prints stats at the end of marking

  low_verbose,       // low verbose, mostly per region and per major event

  medium_verbose,    // a bit more detailed than low

  high_verbose       // per object verbose

} CMVerboseLevel;

class YoungList;

// Root Regions are regions that are not empty at the beginning of a

// marking cycle and which we might collect during an evacuation pause

// while the cycle is active. Given that, during evacuation pauses, we

// do not copy objects that are explicitly marked, what we have to do

// for the root regions is to scan them and mark all objects reachable

// from them. According to the SATB assumptions, we only need to visit

// each object once during marking. So, as long as we finish this scan

// before the next evacuation pause, we can copy the objects from the

// root regions without having to mark them or do anything else to them.

//

// Currently, we only support root region scanning once (at the start

// of the marking cycle) and the root regions are all the survivor

// regions populated during the initial-mark pause.

class CMRootRegions VALUE_OBJ_CLASS_SPEC {

private:

  YoungList*           _young_list;

  ConcurrentMark*      _cm;

  volatile bool        _scan_in_progress;

  volatile bool        _should_abort;

  HeapRegion* volatile _next_survivor;

public:

  CMRootRegions();

  // We actually do most of the initialization in this method.

  void init(G1CollectedHeap* g1h, ConcurrentMark* cm);

  // Reset the claiming / scanning of the root regions.

  void prepare_for_scan();

  // Forces get_next() to return NULL so that the iteration aborts early.

  void abort() { _should_abort = true; }

  // Return true if the CM thread are actively scanning root regions,

  // false otherwise.

  bool scan_in_progress() { return _scan_in_progress; }

  // Claim the next root region to scan atomically, or return NULL if

  // all have been claimed.

  HeapRegion* claim_next();

  // Flag that we're done with root region scanning and notify anyone

  // who's waiting on it. If aborted is false, assume that all regions

  // have been claimed.

  void scan_finished();

  // If CM threads are still scanning root regions, wait until they

  // are done. Return true if we had to wait, false otherwise.

  bool wait_until_scan_finished();

};

class ConcurrentMarkThread;

class ConcurrentMark: public CHeapObj<mtGC> {

  friend class CMMarkStack;

  friend class ConcurrentMarkThread;

  friend class CMTask;

  friend class CMBitMapClosure;

  friend class CMGlobalObjectClosure;

  friend class CMRemarkTask;

  friend class CMConcurrentMarkingTask;

  friend class G1ParNoteEndTask;

  friend class CalcLiveObjectsClosure;

  friend class G1CMRefProcTaskProxy;

  friend class G1CMRefProcTaskExecutor;

  friend class G1CMKeepAliveAndDrainClosure;

  friend class G1CMDrainMarkingStackClosure;

protected:

  ConcurrentMarkThread* _cmThread;   // the thread doing the work

  G1CollectedHeap*      _g1h;        // the heap.

  uint                  _parallel_marking_threads; // the number of marking

                                                   // threads we're use

  uint                  _max_parallel_marking_threads; // max number of marking

                                                   // threads we'll ever use

  double                _sleep_factor; // how much we have to sleep, with

                                       // respect to the work we just did, to

                                       // meet the marking overhead goal

  double                _marking_task_overhead; // marking target overhead for

                                                // a single task

  // same as the two above, but for the cleanup task

  double                _cleanup_sleep_factor;

  double                _cleanup_task_overhead;

  FreeRegionList        _cleanup_list;

  // Concurrent marking support structures

  CMBitMap                _markBitMap1;

  CMBitMap                _markBitMap2;

  CMBitMapRO*             _prevMarkBitMap; // completed mark bitmap

  CMBitMap*               _nextMarkBitMap; // under-construction mark bitmap

  BitMap                  _region_bm;

  BitMap                  _card_bm;

  // Heap bounds

  HeapWord*               _heap_start;

  HeapWord*               _heap_end;

  // Root region tracking and claiming.

  CMRootRegions           _root_regions;

  // For gray objects

  CMMarkStack             _markStack; // Grey objects behind global finger.

  HeapWord* volatile      _finger;  // the global finger, region aligned,

                                    // always points to the end of the

                                    // last claimed region

  // marking tasks

  uint                    _max_worker_id;// maximum worker id

  uint                    _active_tasks; // task num currently active

  CMTask**                _tasks;        // task queue array (max_worker_id len)

  CMTaskQueueSet*         _task_queues;  // task queue set

  ParallelTaskTerminator  _terminator;   // for termination

  // Two sync barriers that are used to synchronise tasks when an

  // overflow occurs. The algorithm is the following. All tasks enter

  // the first one to ensure that they have all stopped manipulating

  // the global data structures. After they exit it, they re-initialise

  // their data structures and task 0 re-initialises the global data

  // structures. Then, they enter the second sync barrier. This

  // ensure, that no task starts doing work before all data

  // structures (local and global) have been re-initialised. When they

  // exit it, they are free to start working again.

  WorkGangBarrierSync     _first_overflow_barrier_sync;

  WorkGangBarrierSync     _second_overflow_barrier_sync;

  // this is set by any task, when an overflow on the global data

  // structures is detected.

  volatile bool           _has_overflown;

  // true: marking is concurrent, false: we're in remark

  volatile bool           _concurrent;

  // set at the end of a Full GC so that marking aborts

  volatile bool           _has_aborted;

  // used when remark aborts due to an overflow to indicate that

  // another concurrent marking phase should start

  volatile bool           _restart_for_overflow;

  // This is true from the very start of concurrent marking until the

  // point when all the tasks complete their work. It is really used

  // to determine the points between the end of concurrent marking and

  // time of remark.

  volatile bool           _concurrent_marking_in_progress;

  // verbose level

  CMVerboseLevel          _verbose_level;

  // All of these times are in ms.

  NumberSeq _init_times;

  NumberSeq _remark_times;

  NumberSeq   _remark_mark_times;

  NumberSeq   _remark_weak_ref_times;

  NumberSeq _cleanup_times;

  double    _total_counting_time;

  double    _total_rs_scrub_time;

  double*   _accum_task_vtime;   // accumulated task vtime

  FlexibleWorkGang* _parallel_workers;

  ForceOverflowSettings _force_overflow_conc;

  ForceOverflowSettings _force_overflow_stw;

  void weakRefsWork(bool clear_all_soft_refs);

  void swapMarkBitMaps();

  // It resets the global marking data structures, as well as the

  // task local ones; should be called during initial mark.

  void reset();

  // Resets all the marking data structures. Called when we have to restart

  // marking or when marking completes (via set_non_marking_state below).

  void reset_marking_state(bool clear_overflow = true);

  // We do this after we're done with marking so that the marking data

  // structures are initialised to a sensible and predictable state.

  void set_non_marking_state();

  // Called to indicate how many threads are currently active.

  void set_concurrency(uint active_tasks);

  // It should be called to indicate which phase we're in (concurrent

  // mark or remark) and how many threads are currently active.

  void set_concurrency_and_phase(uint active_tasks, bool concurrent);

  // prints all gathered CM-related statistics

  void print_stats();

  bool cleanup_list_is_empty() {

    return _cleanup_list.is_empty();

  }

  // accessor methods