1 /* 2 * Copyright (C) 2011 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_MARK_SWEEP_H_ 18 #define ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_ 19 20 #include <memory> 21 22 #include "atomic.h" 23 #include "barrier.h" 24 #include "base/macros.h" 25 #include "base/mutex.h" 26 #include "garbage_collector.h" 27 #include "gc_root.h" 28 #include "gc/accounting/heap_bitmap.h" 29 #include "immune_region.h" 30 #include "object_callbacks.h" 31 #include "offsets.h" 32 33 namespace art { 34 35 namespace mirror { 36 class Class; 37 class Object; 38 class Reference; 39 } // namespace mirror 40 41 class Thread; 42 enum VisitRootFlags : uint8_t; 43 44 namespace gc { 45 46 class Heap; 47 48 namespace accounting { 49 template<typename T> class AtomicStack; 50 typedef AtomicStack<mirror::Object*> ObjectStack; 51 } // namespace accounting 52 53 namespace collector { 54 55 class MarkSweep : public GarbageCollector { 56 public: 57 explicit MarkSweep(Heap* heap, bool is_concurrent, const std::string& name_prefix = ""); 58 59 ~MarkSweep() {} 60 61 virtual void RunPhases() OVERRIDE NO_THREAD_SAFETY_ANALYSIS; 62 void InitializePhase(); 63 void MarkingPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 64 void PausePhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_); 65 void ReclaimPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 66 void FinishPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 67 virtual void MarkReachableObjects() 68 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 69 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 70 71 bool IsConcurrent() const { 72 return is_concurrent_; 73 } 74 75 virtual GcType GetGcType() const OVERRIDE { 76 return kGcTypeFull; 77 } 78 79 virtual CollectorType GetCollectorType() const OVERRIDE { 80 return is_concurrent_ ? kCollectorTypeCMS : kCollectorTypeMS; 81 } 82 83 // Initializes internal structures. 84 void Init(); 85 86 // Find the default mark bitmap. 87 void FindDefaultSpaceBitmap(); 88 89 // Marks all objects in the root set at the start of a garbage collection. 90 void MarkRoots(Thread* self) 91 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 92 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 93 94 void MarkNonThreadRoots() 95 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 96 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 97 98 void MarkConcurrentRoots(VisitRootFlags flags) 99 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 100 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 101 102 void MarkRootsCheckpoint(Thread* self, bool revoke_ros_alloc_thread_local_buffers_at_checkpoint) 103 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 104 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 105 106 // Builds a mark stack and recursively mark until it empties. 107 void RecursiveMark() 108 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 109 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 110 111 // Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie 112 // the image. Mark that portion of the heap as immune. 113 virtual void BindBitmaps() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 114 115 // Builds a mark stack with objects on dirty cards and recursively mark until it empties. 116 void RecursiveMarkDirtyObjects(bool paused, byte minimum_age) 117 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 118 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 119 120 // Remarks the root set after completing the concurrent mark. 121 void ReMarkRoots() 122 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 123 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 124 125 void ProcessReferences(Thread* self) 126 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 127 128 // Update and mark references from immune spaces. 129 void UpdateAndMarkModUnion() 130 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 131 132 // Pre clean cards to reduce how much work is needed in the pause. 133 void PreCleanCards() 134 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 135 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 136 137 // Sweeps unmarked objects to complete the garbage collection. Virtual as by default it sweeps 138 // all allocation spaces. Partial and sticky GCs want to just sweep a subset of the heap. 139 virtual void Sweep(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 140 141 // Sweeps unmarked objects to complete the garbage collection. 142 void SweepLargeObjects(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 143 144 // Sweep only pointers within an array. WARNING: Trashes objects. 145 void SweepArray(accounting::ObjectStack* allocation_stack_, bool swap_bitmaps) 146 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 147 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 148 149 // Blackens an object. 150 void ScanObject(mirror::Object* obj) 151 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 152 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 153 154 // No thread safety analysis due to lambdas. 155 template<typename MarkVisitor, typename ReferenceVisitor> 156 void ScanObjectVisit(mirror::Object* obj, const MarkVisitor& visitor, 157 const ReferenceVisitor& ref_visitor) 158 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 159 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 160 161 void SweepSystemWeaks(Thread* self) 162 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) LOCKS_EXCLUDED(Locks::heap_bitmap_lock_); 163 164 static mirror::Object* VerifySystemWeakIsLiveCallback(mirror::Object* obj, void* arg) 165 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 166 167 void VerifySystemWeaks() 168 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 169 170 // Verify that an object is live, either in a live bitmap or in the allocation stack. 171 void VerifyIsLive(const mirror::Object* obj) 172 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 173 174 static mirror::Object* MarkObjectCallback(mirror::Object* obj, void* arg) 175 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 176 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 177 178 static void MarkHeapReferenceCallback(mirror::HeapReference<mirror::Object>* ref, void* arg) 179 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 180 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 181 182 static bool HeapReferenceMarkedCallback(mirror::HeapReference<mirror::Object>* ref, void* arg) 183 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 184 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 185 186 static void MarkRootCallback(mirror::Object** root, void* arg, const RootInfo& root_info) 187 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 188 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 189 190 static void VerifyRootMarked(mirror::Object** root, void* arg, const RootInfo& root_info) 191 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 192 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 193 194 static void ProcessMarkStackCallback(void* arg) 195 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 196 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 197 198 static void MarkRootParallelCallback(mirror::Object** root, void* arg, const RootInfo& root_info) 199 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 200 201 // Marks an object. 202 void MarkObject(mirror::Object* obj) 203 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 204 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 205 206 Barrier& GetBarrier() { 207 return *gc_barrier_; 208 } 209 210 // Schedules an unmarked object for reference processing. 211 void DelayReferenceReferent(mirror::Class* klass, mirror::Reference* reference) 212 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 213 214 protected: 215 // Returns true if the object has its bit set in the mark bitmap. 216 bool IsMarked(const mirror::Object* object) const 217 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 218 219 static mirror::Object* IsMarkedCallback(mirror::Object* object, void* arg) 220 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 221 222 static void VerifyImageRootVisitor(mirror::Object* root, void* arg) 223 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 224 225 void MarkObjectNonNull(mirror::Object* obj) 226 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 227 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 228 229 // Marks an object atomically, safe to use from multiple threads. 230 void MarkObjectNonNullParallel(mirror::Object* obj); 231 232 // Returns true if we need to add obj to a mark stack. 233 bool MarkObjectParallel(const mirror::Object* obj) NO_THREAD_SAFETY_ANALYSIS; 234 235 // Verify the roots of the heap and print out information related to any invalid roots. 236 // Called in MarkObject, so may we may not hold the mutator lock. 237 void VerifyRoots() 238 NO_THREAD_SAFETY_ANALYSIS; 239 240 // Expand mark stack to 2x its current size. 241 void ExpandMarkStack() EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 242 void ResizeMarkStack(size_t new_size) EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 243 244 // Returns how many threads we should use for the current GC phase based on if we are paused, 245 // whether or not we care about pauses. 246 size_t GetThreadCount(bool paused) const; 247 248 static void VerifyRootCallback(mirror::Object** root, void* arg, const RootInfo& root_info); 249 250 void VerifyRoot(const mirror::Object* root, const RootInfo& root_info) NO_THREAD_SAFETY_ANALYSIS; 251 252 // Push a single reference on a mark stack. 253 void PushOnMarkStack(mirror::Object* obj); 254 255 // Blackens objects grayed during a garbage collection. 256 void ScanGrayObjects(bool paused, byte minimum_age) 257 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 258 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 259 260 // Recursively blackens objects on the mark stack. 261 void ProcessMarkStack(bool paused) 262 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 263 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 264 265 void ProcessMarkStackParallel(size_t thread_count) 266 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 267 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 268 269 // Used to Get around thread safety annotations. The call is from MarkingPhase and is guarded by 270 // IsExclusiveHeld. 271 void RevokeAllThreadLocalAllocationStacks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 272 273 // Revoke all the thread-local buffers. 274 void RevokeAllThreadLocalBuffers(); 275 276 // Whether or not we count how many of each type of object were scanned. 277 static const bool kCountScannedTypes = false; 278 279 // Current space, we check this space first to avoid searching for the appropriate space for an 280 // object. 281 accounting::ContinuousSpaceBitmap* current_space_bitmap_; 282 // Cache the heap's mark bitmap to prevent having to do 2 loads during slow path marking. 283 accounting::HeapBitmap* mark_bitmap_; 284 285 accounting::ObjectStack* mark_stack_; 286 287 // Immune region, every object inside the immune range is assumed to be marked. 288 ImmuneRegion immune_region_; 289 290 // Parallel finger. 291 AtomicInteger atomic_finger_; 292 // Number of classes scanned, if kCountScannedTypes. 293 AtomicInteger class_count_; 294 // Number of arrays scanned, if kCountScannedTypes. 295 AtomicInteger array_count_; 296 // Number of non-class/arrays scanned, if kCountScannedTypes. 297 AtomicInteger other_count_; 298 AtomicInteger large_object_test_; 299 AtomicInteger large_object_mark_; 300 AtomicInteger overhead_time_; 301 AtomicInteger work_chunks_created_; 302 AtomicInteger work_chunks_deleted_; 303 AtomicInteger reference_count_; 304 AtomicInteger mark_null_count_; 305 AtomicInteger mark_immune_count_; 306 AtomicInteger mark_fastpath_count_; 307 AtomicInteger mark_slowpath_count_; 308 309 std::unique_ptr<Barrier> gc_barrier_; 310 Mutex mark_stack_lock_ ACQUIRED_AFTER(Locks::classlinker_classes_lock_); 311 312 const bool is_concurrent_; 313 314 // Verification. 315 size_t live_stack_freeze_size_; 316 317 std::unique_ptr<MemMap> sweep_array_free_buffer_mem_map_; 318 319 private: 320 friend class AddIfReachesAllocSpaceVisitor; // Used by mod-union table. 321 friend class CardScanTask; 322 friend class CheckBitmapVisitor; 323 friend class CheckReferenceVisitor; 324 friend class art::gc::Heap; 325 friend class MarkObjectVisitor; 326 friend class ModUnionCheckReferences; 327 friend class ModUnionClearCardVisitor; 328 friend class ModUnionReferenceVisitor; 329 friend class ModUnionVisitor; 330 friend class ModUnionTableBitmap; 331 friend class ModUnionTableReferenceCache; 332 friend class ModUnionScanImageRootVisitor; 333 template<bool kUseFinger> friend class MarkStackTask; 334 friend class FifoMarkStackChunk; 335 friend class MarkSweepMarkObjectSlowPath; 336 337 DISALLOW_COPY_AND_ASSIGN(MarkSweep); 338 }; 339 340 } // namespace collector 341 } // namespace gc 342 } // namespace art 343 344 #endif // ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_ 345
