cardGeneration.hpp revision 8413:92457dfb91bd 
1/*
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24
25#ifndef SHARE_VM_GC_SHARED_CARDGENERATION_HPP
26#define SHARE_VM_GC_SHARED_CARDGENERATION_HPP
27
28// Class CardGeneration is a generation that is covered by a card table,
29// and uses a card-size block-offset array to implement block_start.
30
31#include "gc/shared/generation.hpp"
32
33class BlockOffsetSharedArray;
34class CompactibleSpace;
35
36class CardGeneration: public Generation {
37  friend class VMStructs;
38 protected:
39  // This is shared with other generations.
40  GenRemSet* _rs;
41  // This is local to this generation.
42  BlockOffsetSharedArray* _bts;
43
44  // Current shrinking effect: this damps shrinking when the heap gets empty.
45  size_t _shrink_factor;
46
47  size_t _min_heap_delta_bytes;   // Minimum amount to expand.
48
49  // Some statistics from before gc started.
50  // These are gathered in the gc_prologue (and should_collect)
51  // to control growing/shrinking policy in spite of promotions.
52  size_t _capacity_at_prologue;
53  size_t _used_at_prologue;
54
55  CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
56                 GenRemSet* remset);
57
58  virtual void assert_correct_size_change_locking() = 0;
59
60  virtual CompactibleSpace* space() const = 0;
61
62 public:
63
64  // Attempt to expand the generation by "bytes".  Expand by at a
65  // minimum "expand_bytes".  Return true if some amount (not
66  // necessarily the full "bytes") was done.
67  virtual bool expand(size_t bytes, size_t expand_bytes);
68
69  // Shrink generation with specified size
70  virtual void shrink(size_t bytes);
71
72  virtual void compute_new_size();
73
74  virtual void clear_remembered_set();
75
76  virtual void invalidate_remembered_set();
77
78  virtual void prepare_for_verify();
79
80  // Grow generation with specified size (returns false if unable to grow)
81  bool grow_by(size_t bytes);
82  // Grow generation to reserved size.
83  bool grow_to_reserved();
84
85  size_t capacity() const;
86  size_t used() const;
87  size_t free() const;
88  MemRegion used_region() const;
89
90  void space_iterate(SpaceClosure* blk, bool usedOnly = false);
91
92  void younger_refs_iterate(OopsInGenClosure* blk);
93
94  bool is_in(const void* p) const;
95
96  CompactibleSpace* first_compaction_space() const;
97};
98
99#endif // SHARE_VM_GC_SHARED_CARDGENERATION_HPP
100