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1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_H_
18 #define ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_H_
19 
20 #include "garbage_collector.h"
21 #include "immune_spaces.h"
22 #include "offsets.h"
23 
24 #include <map>
25 #include <memory>
26 #include <vector>
27 
28 namespace art {
29 class Barrier;
30 class Closure;
31 class RootInfo;
32 
33 namespace mirror {
34 template<class MirrorType> class CompressedReference;
35 template<class MirrorType> class HeapReference;
36 class Object;
37 }  // namespace mirror
38 
39 namespace gc {
40 
41 namespace accounting {
42 template<typename T> class AtomicStack;
43 typedef AtomicStack<mirror::Object> ObjectStack;
44 template <size_t kAlignment> class SpaceBitmap;
45 typedef SpaceBitmap<kObjectAlignment> ContinuousSpaceBitmap;
46 class HeapBitmap;
47 class ReadBarrierTable;
48 }  // namespace accounting
49 
50 namespace space {
51 class RegionSpace;
52 }  // namespace space
53 
54 namespace collector {
55 
56 class ConcurrentCopying : public GarbageCollector {
57  public:
58   // Enable the no-from-space-refs verification at the pause.
59   static constexpr bool kEnableNoFromSpaceRefsVerification = kIsDebugBuild;
60   // Enable the from-space bytes/objects check.
61   static constexpr bool kEnableFromSpaceAccountingCheck = kIsDebugBuild;
62   // Enable verbose mode.
63   static constexpr bool kVerboseMode = false;
64   // If kGrayDirtyImmuneObjects is true then we gray dirty objects in the GC pause to prevent dirty
65   // pages.
66   static constexpr bool kGrayDirtyImmuneObjects = true;
67 
68   ConcurrentCopying(Heap* heap,
69                     bool young_gen,
70                     bool use_generational_cc,
71                     const std::string& name_prefix = "",
72                     bool measure_read_barrier_slow_path = false);
73   ~ConcurrentCopying();
74 
75   void RunPhases() override
76       REQUIRES(!immune_gray_stack_lock_,
77                !mark_stack_lock_,
78                !rb_slow_path_histogram_lock_,
79                !skipped_blocks_lock_);
80   void InitializePhase() REQUIRES_SHARED(Locks::mutator_lock_)
81       REQUIRES(!mark_stack_lock_, !immune_gray_stack_lock_);
82   void MarkingPhase() REQUIRES_SHARED(Locks::mutator_lock_)
83       REQUIRES(!mark_stack_lock_);
84   void CopyingPhase() REQUIRES_SHARED(Locks::mutator_lock_)
85       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
86   void ReclaimPhase() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
87   void FinishPhase() REQUIRES(!mark_stack_lock_,
88                               !rb_slow_path_histogram_lock_,
89                               !skipped_blocks_lock_);
90 
91   void CaptureRssAtPeak() REQUIRES(!mark_stack_lock_);
92   void BindBitmaps() REQUIRES_SHARED(Locks::mutator_lock_)
93       REQUIRES(!Locks::heap_bitmap_lock_);
GetGcType()94   GcType GetGcType() const override {
95     return (use_generational_cc_ && young_gen_)
96         ? kGcTypeSticky
97         : kGcTypePartial;
98   }
GetCollectorType()99   CollectorType GetCollectorType() const override {
100     return kCollectorTypeCC;
101   }
102   void RevokeAllThreadLocalBuffers() override;
103   // Creates inter-region ref bitmaps for region-space and non-moving-space.
104   // Gets called in Heap construction after the two spaces are created.
105   void CreateInterRegionRefBitmaps();
SetRegionSpace(space::RegionSpace * region_space)106   void SetRegionSpace(space::RegionSpace* region_space) {
107     DCHECK(region_space != nullptr);
108     region_space_ = region_space;
109   }
RegionSpace()110   space::RegionSpace* RegionSpace() {
111     return region_space_;
112   }
113   // Assert the to-space invariant for a heap reference `ref` held in `obj` at offset `offset`.
114   void AssertToSpaceInvariant(mirror::Object* obj, MemberOffset offset, mirror::Object* ref)
115       REQUIRES_SHARED(Locks::mutator_lock_);
116   // Assert the to-space invariant for a GC root reference `ref`.
117   void AssertToSpaceInvariant(GcRootSource* gc_root_source, mirror::Object* ref)
118       REQUIRES_SHARED(Locks::mutator_lock_);
IsInToSpace(mirror::Object * ref)119   bool IsInToSpace(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_) {
120     DCHECK(ref != nullptr);
121     return IsMarked(ref) == ref;
122   }
123   // Mark object `from_ref`, copying it to the to-space if needed.
124   template<bool kGrayImmuneObject = true, bool kNoUnEvac = false, bool kFromGCThread = false>
125   ALWAYS_INLINE mirror::Object* Mark(Thread* const self,
126                                      mirror::Object* from_ref,
127                                      mirror::Object* holder = nullptr,
128                                      MemberOffset offset = MemberOffset(0))
129       REQUIRES_SHARED(Locks::mutator_lock_)
130       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
131   ALWAYS_INLINE mirror::Object* MarkFromReadBarrier(mirror::Object* from_ref)
132       REQUIRES_SHARED(Locks::mutator_lock_)
133       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
IsMarking()134   bool IsMarking() const {
135     return is_marking_;
136   }
137   // We may want to use read barrier entrypoints before is_marking_ is true since concurrent graying
138   // creates a small window where we might dispatch on these entrypoints.
IsUsingReadBarrierEntrypoints()139   bool IsUsingReadBarrierEntrypoints() const {
140     return is_using_read_barrier_entrypoints_;
141   }
IsActive()142   bool IsActive() const {
143     return is_active_;
144   }
GetBarrier()145   Barrier& GetBarrier() {
146     return *gc_barrier_;
147   }
IsWeakRefAccessEnabled()148   bool IsWeakRefAccessEnabled() REQUIRES(Locks::thread_list_lock_) {
149     return weak_ref_access_enabled_;
150   }
151   void RevokeThreadLocalMarkStack(Thread* thread) REQUIRES_SHARED(Locks::mutator_lock_)
152       REQUIRES(!mark_stack_lock_);
153 
154   mirror::Object* IsMarked(mirror::Object* from_ref) override
155       REQUIRES_SHARED(Locks::mutator_lock_);
156 
157  private:
158   void PushOntoMarkStack(Thread* const self, mirror::Object* obj)
159       REQUIRES_SHARED(Locks::mutator_lock_)
160       REQUIRES(!mark_stack_lock_);
161   mirror::Object* Copy(Thread* const self,
162                        mirror::Object* from_ref,
163                        mirror::Object* holder,
164                        MemberOffset offset)
165       REQUIRES_SHARED(Locks::mutator_lock_)
166       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
167   // Scan the reference fields of object `to_ref`.
168   template <bool kNoUnEvac>
169   void Scan(mirror::Object* to_ref) REQUIRES_SHARED(Locks::mutator_lock_)
170       REQUIRES(!mark_stack_lock_);
171   // Scan the reference fields of object 'obj' in the dirty cards during
172   // card-table scan. In addition to visiting the references, it also sets the
173   // read-barrier state to gray for Reference-type objects to ensure that
174   // GetReferent() called on these objects calls the read-barrier on the referent.
175   template <bool kNoUnEvac>
176   void ScanDirtyObject(mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_)
177       REQUIRES(!mark_stack_lock_);
178   // Process a field.
179   template <bool kNoUnEvac>
180   void Process(mirror::Object* obj, MemberOffset offset)
181       REQUIRES_SHARED(Locks::mutator_lock_)
182       REQUIRES(!mark_stack_lock_ , !skipped_blocks_lock_, !immune_gray_stack_lock_);
183   void VisitRoots(mirror::Object*** roots, size_t count, const RootInfo& info) override
184       REQUIRES_SHARED(Locks::mutator_lock_)
185       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
186   template<bool kGrayImmuneObject>
187   void MarkRoot(Thread* const self, mirror::CompressedReference<mirror::Object>* root)
188       REQUIRES_SHARED(Locks::mutator_lock_)
189       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
190   void VisitRoots(mirror::CompressedReference<mirror::Object>** roots,
191                   size_t count,
192                   const RootInfo& info) override
193       REQUIRES_SHARED(Locks::mutator_lock_)
194       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
195   void VerifyNoFromSpaceReferences() REQUIRES(Locks::mutator_lock_);
196   accounting::ObjectStack* GetAllocationStack();
197   accounting::ObjectStack* GetLiveStack();
198   void ProcessMarkStack() override REQUIRES_SHARED(Locks::mutator_lock_)
199       REQUIRES(!mark_stack_lock_);
200   bool ProcessMarkStackOnce() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
201   void ProcessMarkStackRef(mirror::Object* to_ref) REQUIRES_SHARED(Locks::mutator_lock_)
202       REQUIRES(!mark_stack_lock_);
203   void GrayAllDirtyImmuneObjects()
204       REQUIRES(Locks::mutator_lock_)
205       REQUIRES(!mark_stack_lock_);
206   void GrayAllNewlyDirtyImmuneObjects()
207       REQUIRES(Locks::mutator_lock_)
208       REQUIRES(!mark_stack_lock_);
209   void VerifyGrayImmuneObjects()
210       REQUIRES(Locks::mutator_lock_)
211       REQUIRES(!mark_stack_lock_);
212   void VerifyNoMissingCardMarks()
213       REQUIRES(Locks::mutator_lock_)
214       REQUIRES(!mark_stack_lock_);
215   template <typename Processor>
216   size_t ProcessThreadLocalMarkStacks(bool disable_weak_ref_access,
217                                       Closure* checkpoint_callback,
218                                       const Processor& processor)
219       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
220   void RevokeThreadLocalMarkStacks(bool disable_weak_ref_access, Closure* checkpoint_callback)
221       REQUIRES_SHARED(Locks::mutator_lock_);
222   void SwitchToSharedMarkStackMode() REQUIRES_SHARED(Locks::mutator_lock_)
223       REQUIRES(!mark_stack_lock_);
224   void SwitchToGcExclusiveMarkStackMode() REQUIRES_SHARED(Locks::mutator_lock_);
225   void DelayReferenceReferent(ObjPtr<mirror::Class> klass,
226                               ObjPtr<mirror::Reference> reference) override
227       REQUIRES_SHARED(Locks::mutator_lock_);
228   void ProcessReferences(Thread* self) REQUIRES_SHARED(Locks::mutator_lock_);
229   mirror::Object* MarkObject(mirror::Object* from_ref) override
230       REQUIRES_SHARED(Locks::mutator_lock_)
231       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
232   void MarkHeapReference(mirror::HeapReference<mirror::Object>* from_ref,
233                          bool do_atomic_update) override
234       REQUIRES_SHARED(Locks::mutator_lock_)
235       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
236   bool IsMarkedInUnevacFromSpace(mirror::Object* from_ref)
237       REQUIRES_SHARED(Locks::mutator_lock_);
238   bool IsMarkedInNonMovingSpace(mirror::Object* from_ref)
239       REQUIRES_SHARED(Locks::mutator_lock_);
240   bool IsNullOrMarkedHeapReference(mirror::HeapReference<mirror::Object>* field,
241                                    bool do_atomic_update) override
242       REQUIRES_SHARED(Locks::mutator_lock_);
243   void SweepSystemWeaks(Thread* self)
244       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Locks::heap_bitmap_lock_);
245   // Sweep unmarked objects to complete the garbage collection. Full GCs sweep
246   // all allocation spaces (except the region space). Sticky-bit GCs just sweep
247   // a subset of the heap.
248   void Sweep(bool swap_bitmaps)
249       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_, !mark_stack_lock_);
250   // Sweep only pointers within an array.
251   void SweepArray(accounting::ObjectStack* allocation_stack_, bool swap_bitmaps)
252       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_, !mark_stack_lock_);
253   void SweepLargeObjects(bool swap_bitmaps)
254       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_);
255   void MarkZygoteLargeObjects()
256       REQUIRES_SHARED(Locks::mutator_lock_);
257   void FillWithDummyObject(Thread* const self, mirror::Object* dummy_obj, size_t byte_size)
258       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_)
259       REQUIRES_SHARED(Locks::mutator_lock_);
260   mirror::Object* AllocateInSkippedBlock(Thread* const self, size_t alloc_size)
261       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_)
262       REQUIRES_SHARED(Locks::mutator_lock_);
263   void CheckEmptyMarkStack() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
264   void IssueEmptyCheckpoint() REQUIRES_SHARED(Locks::mutator_lock_);
265   bool IsOnAllocStack(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
266   mirror::Object* GetFwdPtr(mirror::Object* from_ref)
267       REQUIRES_SHARED(Locks::mutator_lock_);
268   void FlipThreadRoots() REQUIRES(!Locks::mutator_lock_);
269   void SwapStacks() REQUIRES_SHARED(Locks::mutator_lock_);
270   void RecordLiveStackFreezeSize(Thread* self);
271   void ComputeUnevacFromSpaceLiveRatio();
272   void LogFromSpaceRefHolder(mirror::Object* obj, MemberOffset offset)
273       REQUIRES_SHARED(Locks::mutator_lock_);
274   // Dump information about reference `ref` and return it as a string.
275   // Use `ref_name` to name the reference in messages. Each message is prefixed with `indent`.
276   std::string DumpReferenceInfo(mirror::Object* ref, const char* ref_name, const char* indent = "")
277       REQUIRES_SHARED(Locks::mutator_lock_);
278   // Dump information about heap reference `ref`, referenced from object `obj` at offset `offset`,
279   // and return it as a string.
280   std::string DumpHeapReference(mirror::Object* obj, MemberOffset offset, mirror::Object* ref)
281       REQUIRES_SHARED(Locks::mutator_lock_);
282   // Dump information about GC root `ref` and return it as a string.
283   std::string DumpGcRoot(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
284   void AssertToSpaceInvariantInNonMovingSpace(mirror::Object* obj, mirror::Object* ref)
285       REQUIRES_SHARED(Locks::mutator_lock_);
286   void ReenableWeakRefAccess(Thread* self) REQUIRES_SHARED(Locks::mutator_lock_);
287   void DisableMarking() REQUIRES_SHARED(Locks::mutator_lock_);
288   void IssueDisableMarkingCheckpoint() REQUIRES_SHARED(Locks::mutator_lock_);
289   void ExpandGcMarkStack() REQUIRES_SHARED(Locks::mutator_lock_);
290   mirror::Object* MarkNonMoving(Thread* const self,
291                                 mirror::Object* from_ref,
292                                 mirror::Object* holder = nullptr,
293                                 MemberOffset offset = MemberOffset(0))
294       REQUIRES_SHARED(Locks::mutator_lock_)
295       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_);
296   ALWAYS_INLINE mirror::Object* MarkUnevacFromSpaceRegion(Thread* const self,
297       mirror::Object* from_ref,
298       accounting::SpaceBitmap<kObjectAlignment>* bitmap)
299       REQUIRES_SHARED(Locks::mutator_lock_)
300       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_);
301   template<bool kGrayImmuneObject>
302   ALWAYS_INLINE mirror::Object* MarkImmuneSpace(Thread* const self,
303                                                 mirror::Object* from_ref)
304       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!immune_gray_stack_lock_);
305   void ScanImmuneObject(mirror::Object* obj)
306       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
307   mirror::Object* MarkFromReadBarrierWithMeasurements(Thread* const self,
308                                                       mirror::Object* from_ref)
309       REQUIRES_SHARED(Locks::mutator_lock_)
310       REQUIRES(!mark_stack_lock_, !skipped_blocks_lock_, !immune_gray_stack_lock_);
311   void DumpPerformanceInfo(std::ostream& os) override REQUIRES(!rb_slow_path_histogram_lock_);
312   // Set the read barrier mark entrypoints to non-null.
313   void ActivateReadBarrierEntrypoints();
314 
315   void CaptureThreadRootsForMarking() REQUIRES_SHARED(Locks::mutator_lock_);
316   void AddLiveBytesAndScanRef(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
317   bool TestMarkBitmapForRef(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
318   template <bool kAtomic = false>
319   bool TestAndSetMarkBitForRef(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
320   void PushOntoLocalMarkStack(mirror::Object* ref) REQUIRES_SHARED(Locks::mutator_lock_);
321   void ProcessMarkStackForMarkingAndComputeLiveBytes() REQUIRES_SHARED(Locks::mutator_lock_)
322       REQUIRES(!mark_stack_lock_);
323 
324   space::RegionSpace* region_space_;      // The underlying region space.
325   std::unique_ptr<Barrier> gc_barrier_;
326   std::unique_ptr<accounting::ObjectStack> gc_mark_stack_;
327 
328   // If true, enable generational collection when using the Concurrent Copying
329   // (CC) collector, i.e. use sticky-bit CC for minor collections and (full) CC
330   // for major collections. Generational CC collection is currently only
331   // compatible with Baker read barriers. Set in Heap constructor.
332   const bool use_generational_cc_;
333 
334   // Generational "sticky", only trace through dirty objects in region space.
335   const bool young_gen_;
336 
337   // If true, the GC thread is done scanning marked objects on dirty and aged
338   // card (see ConcurrentCopying::CopyingPhase).
339   Atomic<bool> done_scanning_;
340 
341   // The read-barrier mark-bit stack. Stores object references whose
342   // mark bit has been set by ConcurrentCopying::MarkFromReadBarrier,
343   // so that this bit can be reset at the end of the collection in
344   // ConcurrentCopying::FinishPhase. The mark bit of an object can be
345   // used by mutator read barrier code to quickly test whether that
346   // object has been already marked.
347   std::unique_ptr<accounting::ObjectStack> rb_mark_bit_stack_;
348   // Thread-unsafe Boolean value hinting that `rb_mark_bit_stack_` is
349   // full. A thread-safe test of whether the read-barrier mark-bit
350   // stack is full is implemented by `rb_mark_bit_stack_->AtomicPushBack(ref)`
351   // (see use case in ConcurrentCopying::MarkFromReadBarrier).
352   bool rb_mark_bit_stack_full_;
353 
354   Mutex mark_stack_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
355   std::vector<accounting::ObjectStack*> revoked_mark_stacks_
356       GUARDED_BY(mark_stack_lock_);
357   static constexpr size_t kMarkStackSize = kPageSize;
358   static constexpr size_t kMarkStackPoolSize = 256;
359   std::vector<accounting::ObjectStack*> pooled_mark_stacks_
360       GUARDED_BY(mark_stack_lock_);
361   Thread* thread_running_gc_;
362   bool is_marking_;                       // True while marking is ongoing.
363   // True while we might dispatch on the read barrier entrypoints.
364   bool is_using_read_barrier_entrypoints_;
365   bool is_active_;                        // True while the collection is ongoing.
366   bool is_asserting_to_space_invariant_;  // True while asserting the to-space invariant.
367   ImmuneSpaces immune_spaces_;
368   accounting::ContinuousSpaceBitmap* region_space_bitmap_;
369   // A cache of Heap::GetMarkBitmap().
370   accounting::HeapBitmap* heap_mark_bitmap_;
371   size_t live_stack_freeze_size_;
372   size_t from_space_num_objects_at_first_pause_;  // Computed if kEnableFromSpaceAccountingCheck
373   size_t from_space_num_bytes_at_first_pause_;  // Computed if kEnableFromSpaceAccountingCheck
374   Atomic<int> is_mark_stack_push_disallowed_;
375   enum MarkStackMode {
376     kMarkStackModeOff = 0,      // Mark stack is off.
377     kMarkStackModeThreadLocal,  // All threads except for the GC-running thread push refs onto
378                                 // thread-local mark stacks. The GC-running thread pushes onto and
379                                 // pops off the GC mark stack without a lock.
380     kMarkStackModeShared,       // All threads share the GC mark stack with a lock.
381     kMarkStackModeGcExclusive   // The GC-running thread pushes onto and pops from the GC mark stack
382                                 // without a lock. Other threads won't access the mark stack.
383   };
384   Atomic<MarkStackMode> mark_stack_mode_;
385   bool weak_ref_access_enabled_ GUARDED_BY(Locks::thread_list_lock_);
386 
387   // How many objects and bytes we moved. The GC thread moves many more objects
388   // than mutators.  Therefore, we separate the two to avoid CAS.  Bytes_moved_ and
389   // bytes_moved_gc_thread_ are critical for GC triggering; the others are just informative.
390   Atomic<size_t> bytes_moved_;  // Used by mutators
391   Atomic<size_t> objects_moved_;  // Used by mutators
392   size_t bytes_moved_gc_thread_;  // Used by GC
393   size_t objects_moved_gc_thread_;  // Used by GC
394   Atomic<uint64_t> cumulative_bytes_moved_;
395   Atomic<uint64_t> cumulative_objects_moved_;
396 
397   // copied_live_bytes_ratio_sum_ is read and written by CC per GC, in
398   // ReclaimPhase, and is read by DumpPerformanceInfo (potentially from another
399   // thread). However, at present, DumpPerformanceInfo is only called when the
400   // runtime shuts down, so no concurrent access. The same reasoning goes for
401   // gc_count_ and reclaimed_bytes_ratio_sum_
402 
403   // The sum of of all copied live bytes ratio (to_bytes/from_bytes)
404   float copied_live_bytes_ratio_sum_;
405   // The number of GC counts, used to calculate the average above. (It doesn't
406   // include GC where from_bytes is zero, IOW, from-space is empty, which is
407   // possible for minor GC if all allocated objects are in non-moving
408   // space.)
409   size_t gc_count_;
410   // Bit is set if the corresponding object has inter-region references that
411   // were found during the marking phase of two-phase full-heap GC cycle.
412   std::unique_ptr<accounting::ContinuousSpaceBitmap> region_space_inter_region_bitmap_;
413   std::unique_ptr<accounting::ContinuousSpaceBitmap> non_moving_space_inter_region_bitmap_;
414 
415   // reclaimed_bytes_ratio = reclaimed_bytes/num_allocated_bytes per GC cycle
416   float reclaimed_bytes_ratio_sum_;
417 
418   // The skipped blocks are memory blocks/chucks that were copies of
419   // objects that were unused due to lost races (cas failures) at
420   // object copy/forward pointer install. They may be reused.
421   // Skipped blocks are always in region space. Their size is included directly
422   // in num_bytes_allocated_, i.e. they are treated as allocated, but may be directly
423   // used without going through a GC cycle like other objects. They are reused only
424   // if we run out of region space. TODO: Revisit this design.
425   Mutex skipped_blocks_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
426   std::multimap<size_t, uint8_t*> skipped_blocks_map_ GUARDED_BY(skipped_blocks_lock_);
427   Atomic<size_t> to_space_bytes_skipped_;
428   Atomic<size_t> to_space_objects_skipped_;
429 
430   // If measure_read_barrier_slow_path_ is true, we count how long is spent in MarkFromReadBarrier
431   // and also log.
432   bool measure_read_barrier_slow_path_;
433   // mark_from_read_barrier_measurements_ is true if systrace is enabled or
434   // measure_read_barrier_time_ is true.
435   bool mark_from_read_barrier_measurements_;
436   Atomic<uint64_t> rb_slow_path_ns_;
437   Atomic<uint64_t> rb_slow_path_count_;
438   Atomic<uint64_t> rb_slow_path_count_gc_;
439   mutable Mutex rb_slow_path_histogram_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
440   Histogram<uint64_t> rb_slow_path_time_histogram_ GUARDED_BY(rb_slow_path_histogram_lock_);
441   uint64_t rb_slow_path_count_total_ GUARDED_BY(rb_slow_path_histogram_lock_);
442   uint64_t rb_slow_path_count_gc_total_ GUARDED_BY(rb_slow_path_histogram_lock_);
443 
444   accounting::ReadBarrierTable* rb_table_;
445   bool force_evacuate_all_;  // True if all regions are evacuated.
446   Atomic<bool> updated_all_immune_objects_;
447   bool gc_grays_immune_objects_;
448   Mutex immune_gray_stack_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
449   std::vector<mirror::Object*> immune_gray_stack_ GUARDED_BY(immune_gray_stack_lock_);
450 
451   // Class of java.lang.Object. Filled in from WellKnownClasses in FlipCallback. Must
452   // be filled in before flipping thread roots so that FillDummyObject can run. Not
453   // ObjPtr since the GC may transition to suspended and runnable between phases.
454   mirror::Class* java_lang_Object_;
455 
456   // Sweep array free buffer, used to sweep the spaces based on an array more
457   // efficiently, by recording dead objects to be freed in batches (see
458   // ConcurrentCopying::SweepArray).
459   MemMap sweep_array_free_buffer_mem_map_;
460 
461   // Use signed because after_gc may be larger than before_gc.
462   int64_t num_bytes_allocated_before_gc_;
463 
464   class ActivateReadBarrierEntrypointsCallback;
465   class ActivateReadBarrierEntrypointsCheckpoint;
466   class AssertToSpaceInvariantFieldVisitor;
467   class AssertToSpaceInvariantRefsVisitor;
468   class ClearBlackPtrsVisitor;
469   class ComputeUnevacFromSpaceLiveRatioVisitor;
470   class DisableMarkingCallback;
471   class DisableMarkingCheckpoint;
472   class DisableWeakRefAccessCallback;
473   class FlipCallback;
474   template <bool kConcurrent> class GrayImmuneObjectVisitor;
475   class ImmuneSpaceScanObjVisitor;
476   class LostCopyVisitor;
477   template <bool kNoUnEvac> class RefFieldsVisitor;
478   class RevokeThreadLocalMarkStackCheckpoint;
479   class ScopedGcGraysImmuneObjects;
480   class ThreadFlipVisitor;
481   class VerifyGrayImmuneObjectsVisitor;
482   class VerifyNoFromSpaceRefsFieldVisitor;
483   class VerifyNoFromSpaceRefsVisitor;
484   class VerifyNoMissingCardMarkVisitor;
485   class ImmuneSpaceCaptureRefsVisitor;
486   template <bool kAtomicTestAndSet = false> class CaptureRootsForMarkingVisitor;
487   class CaptureThreadRootsForMarkingAndCheckpoint;
488   template <bool kHandleInterRegionRefs> class ComputeLiveBytesAndMarkRefFieldsVisitor;
489 
490   DISALLOW_IMPLICIT_CONSTRUCTORS(ConcurrentCopying);
491 };
492 
493 }  // namespace collector
494 }  // namespace gc
495 }  // namespace art
496 
497 #endif  // ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_H_
498