g1Allocator.hpp revision 8413:92457dfb91bd 
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24
25#ifndef SHARE_VM_GC_G1_G1ALLOCATOR_HPP
26#define SHARE_VM_GC_G1_G1ALLOCATOR_HPP
27
28#include "gc/g1/g1AllocRegion.hpp"
29#include "gc/g1/g1AllocationContext.hpp"
30#include "gc/g1/g1InCSetState.hpp"
31#include "gc/shared/collectedHeap.hpp"
32#include "gc/shared/plab.hpp"
33
34class EvacuationInfo;
35
36// Base class for G1 allocators.
37class G1Allocator : public CHeapObj<mtGC> {
38  friend class VMStructs;
39protected:
40  G1CollectedHeap* _g1h;
41
42  // Outside of GC pauses, the number of bytes used in all regions other
43  // than the current allocation region.
44  size_t _summary_bytes_used;
45
46public:
47   G1Allocator(G1CollectedHeap* heap) :
48     _g1h(heap), _summary_bytes_used(0) { }
49
50   static G1Allocator* create_allocator(G1CollectedHeap* g1h);
51
52   virtual void init_mutator_alloc_region() = 0;
53   virtual void release_mutator_alloc_region() = 0;
54
55   virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
56   virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) = 0;
57   virtual void abandon_gc_alloc_regions() = 0;
58
59   virtual MutatorAllocRegion*    mutator_alloc_region(AllocationContext_t context) = 0;
60   virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
61   virtual OldGCAllocRegion*      old_gc_alloc_region(AllocationContext_t context) = 0;
62   virtual size_t                 used() = 0;
63   virtual bool                   is_retained_old_region(HeapRegion* hr) = 0;
64
65   void                           reuse_retained_old_region(EvacuationInfo& evacuation_info,
66                                                            OldGCAllocRegion* old,
67                                                            HeapRegion** retained);
68
69   size_t used_unlocked() const {
70     return _summary_bytes_used;
71   }
72
73   void increase_used(size_t bytes) {
74     _summary_bytes_used += bytes;
75   }
76
77   void decrease_used(size_t bytes) {
78     assert(_summary_bytes_used >= bytes,
79            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
80                _summary_bytes_used, bytes));
81     _summary_bytes_used -= bytes;
82   }
83
84   void set_used(size_t bytes) {
85     _summary_bytes_used = bytes;
86   }
87
88   virtual HeapRegion* new_heap_region(uint hrs_index,
89                                       G1BlockOffsetSharedArray* sharedOffsetArray,
90                                       MemRegion mr) {
91     return new HeapRegion(hrs_index, sharedOffsetArray, mr);
92   }
93};
94
95// The default allocator for G1.
96class G1DefaultAllocator : public G1Allocator {
97protected:
98  // Alloc region used to satisfy mutator allocation requests.
99  MutatorAllocRegion _mutator_alloc_region;
100
101  // Alloc region used to satisfy allocation requests by the GC for
102  // survivor objects.
103  SurvivorGCAllocRegion _survivor_gc_alloc_region;
104
105  // Alloc region used to satisfy allocation requests by the GC for
106  // old objects.
107  OldGCAllocRegion _old_gc_alloc_region;
108
109  HeapRegion* _retained_old_gc_alloc_region;
110public:
111  G1DefaultAllocator(G1CollectedHeap* heap) : G1Allocator(heap), _retained_old_gc_alloc_region(NULL) { }
112
113  virtual void init_mutator_alloc_region();
114  virtual void release_mutator_alloc_region();
115
116  virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
117  virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
118  virtual void abandon_gc_alloc_regions();
119
120  virtual bool is_retained_old_region(HeapRegion* hr) {
121    return _retained_old_gc_alloc_region == hr;
122  }
123
124  virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
125    return &_mutator_alloc_region;
126  }
127
128  virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
129    return &_survivor_gc_alloc_region;
130  }
131
132  virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
133    return &_old_gc_alloc_region;
134  }
135
136  virtual size_t used() {
137    assert(Heap_lock->owner() != NULL,
138           "Should be owned on this thread's behalf.");
139    size_t result = _summary_bytes_used;
140
141    // Read only once in case it is set to NULL concurrently
142    HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get();
143    if (hr != NULL) {
144      result += hr->used();
145    }
146    return result;
147  }
148};
149
150class G1PLAB: public PLAB {
151private:
152  bool _retired;
153
154public:
155  G1PLAB(size_t gclab_word_size);
156  virtual ~G1PLAB() {
157    guarantee(_retired, "Allocation buffer has not been retired");
158  }
159
160  virtual void set_buf(HeapWord* buf) {
161    PLAB::set_buf(buf);
162    _retired = false;
163  }
164
165  virtual void retire() {
166    if (_retired) {
167      return;
168    }
169    PLAB::retire();
170    _retired = true;
171  }
172
173  virtual void flush_and_retire_stats(PLABStats* stats) {
174    PLAB::flush_and_retire_stats(stats);
175    _retired = true;
176  }
177};
178
179class G1ParGCAllocator : public CHeapObj<mtGC> {
180  friend class G1ParScanThreadState;
181protected:
182  G1CollectedHeap* _g1h;
183
184  // The survivor alignment in effect in bytes.
185  // == 0 : don't align survivors
186  // != 0 : align survivors to that alignment
187  // These values were chosen to favor the non-alignment case since some
188  // architectures have a special compare against zero instructions.
189  const uint _survivor_alignment_bytes;
190
191  virtual void retire_alloc_buffers() = 0;
192  virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
193
194  // Calculate the survivor space object alignment in bytes. Returns that or 0 if
195  // there are no restrictions on survivor alignment.
196  static uint calc_survivor_alignment_bytes() {
197    assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
198    if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
199      // No need to align objects in the survivors differently, return 0
200      // which means "survivor alignment is not used".
201      return 0;
202    } else {
203      assert(SurvivorAlignmentInBytes > 0, "sanity");
204      return SurvivorAlignmentInBytes;
205    }
206  }
207
208public:
209  G1ParGCAllocator(G1CollectedHeap* g1h) :
210    _g1h(g1h), _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { }
211  virtual ~G1ParGCAllocator() { }
212
213  static G1ParGCAllocator* create_allocator(G1CollectedHeap* g1h);
214
215  virtual void waste(size_t& wasted, size_t& undo_wasted) = 0;
216
217  // Allocate word_sz words in dest, either directly into the regions or by
218  // allocating a new PLAB. Returns the address of the allocated memory, NULL if
219  // not successful.
220  HeapWord* allocate_direct_or_new_plab(InCSetState dest,
221                                        size_t word_sz,
222                                        AllocationContext_t context);
223
224  // Allocate word_sz words in the PLAB of dest.  Returns the address of the
225  // allocated memory, NULL if not successful.
226  HeapWord* plab_allocate(InCSetState dest,
227                          size_t word_sz,
228                          AllocationContext_t context) {
229    G1PLAB* buffer = alloc_buffer(dest, context);
230    if (_survivor_alignment_bytes == 0) {
231      return buffer->allocate(word_sz);
232    } else {
233      return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes);
234    }
235  }
236
237  HeapWord* allocate(InCSetState dest, size_t word_sz,
238                     AllocationContext_t context) {
239    HeapWord* const obj = plab_allocate(dest, word_sz, context);
240    if (obj != NULL) {
241      return obj;
242    }
243    return allocate_direct_or_new_plab(dest, word_sz, context);
244  }
245
246  void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
247    alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
248  }
249};
250
251class G1DefaultParGCAllocator : public G1ParGCAllocator {
252  G1PLAB  _surviving_alloc_buffer;
253  G1PLAB  _tenured_alloc_buffer;
254  G1PLAB* _alloc_buffers[InCSetState::Num];
255
256public:
257  G1DefaultParGCAllocator(G1CollectedHeap* g1h);
258
259  virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
260    assert(dest.is_valid(),
261           err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()));
262    assert(_alloc_buffers[dest.value()] != NULL,
263           err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()));
264    return _alloc_buffers[dest.value()];
265  }
266
267  virtual void retire_alloc_buffers();
268
269  virtual void waste(size_t& wasted, size_t& undo_wasted);
270};
271
272#endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP
273