mark_sweep.h revision 308351ada0008b0cbe1a5afc31c302c975554ee4
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/accounting/heap_bitmap.h" 28#include "immune_region.h" 29#include "object_callbacks.h" 30#include "offsets.h" 31 32namespace art { 33 34namespace mirror { 35 class Class; 36 class Object; 37 class Reference; 38} // namespace mirror 39 40class Thread; 41enum VisitRootFlags : uint8_t; 42 43namespace gc { 44 45class Heap; 46 47namespace accounting { 48 template<typename T> class AtomicStack; 49 typedef AtomicStack<mirror::Object*> ObjectStack; 50} // namespace accounting 51 52namespace collector { 53 54class MarkSweep : public GarbageCollector { 55 public: 56 explicit MarkSweep(Heap* heap, bool is_concurrent, const std::string& name_prefix = ""); 57 58 ~MarkSweep() {} 59 60 virtual void RunPhases() OVERRIDE NO_THREAD_SAFETY_ANALYSIS; 61 void InitializePhase(); 62 void MarkingPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 63 void PausePhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_); 64 void ReclaimPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 65 void FinishPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 66 virtual void MarkReachableObjects() 67 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 68 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 69 70 bool IsConcurrent() const { 71 return is_concurrent_; 72 } 73 74 virtual GcType GetGcType() const OVERRIDE { 75 return kGcTypeFull; 76 } 77 78 virtual CollectorType GetCollectorType() const OVERRIDE { 79 return is_concurrent_ ? kCollectorTypeCMS : kCollectorTypeMS; 80 } 81 82 // Initializes internal structures. 83 void Init(); 84 85 // Find the default mark bitmap. 86 void FindDefaultSpaceBitmap(); 87 88 // Marks all objects in the root set at the start of a garbage collection. 89 void MarkRoots(Thread* self) 90 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 91 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 92 93 void MarkNonThreadRoots() 94 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 95 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 96 97 void MarkConcurrentRoots(VisitRootFlags flags) 98 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 99 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 100 101 void MarkRootsCheckpoint(Thread* self, bool revoke_ros_alloc_thread_local_buffers_at_checkpoint) 102 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 103 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 104 105 // Builds a mark stack and recursively mark until it empties. 106 void RecursiveMark() 107 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 108 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 109 110 // Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie 111 // the image. Mark that portion of the heap as immune. 112 virtual void BindBitmaps() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 113 114 // Builds a mark stack with objects on dirty cards and recursively mark until it empties. 115 void RecursiveMarkDirtyObjects(bool paused, byte minimum_age) 116 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 117 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 118 119 // Remarks the root set after completing the concurrent mark. 120 void ReMarkRoots() 121 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 122 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 123 124 void ProcessReferences(Thread* self) 125 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 126 127 // Update and mark references from immune spaces. 128 void UpdateAndMarkModUnion() 129 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 130 131 // Pre clean cards to reduce how much work is needed in the pause. 132 void PreCleanCards() 133 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 134 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 135 136 // Sweeps unmarked objects to complete the garbage collection. Virtual as by default it sweeps 137 // all allocation spaces. Partial and sticky GCs want to just sweep a subset of the heap. 138 virtual void Sweep(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 139 140 // Sweeps unmarked objects to complete the garbage collection. 141 void SweepLargeObjects(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 142 143 // Sweep only pointers within an array. WARNING: Trashes objects. 144 void SweepArray(accounting::ObjectStack* allocation_stack_, bool swap_bitmaps) 145 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 146 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 147 148 // Blackens an object. 149 void ScanObject(mirror::Object* obj) 150 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 151 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 152 153 // No thread safety analysis due to lambdas. 154 template<typename MarkVisitor, typename ReferenceVisitor> 155 void ScanObjectVisit(mirror::Object* obj, const MarkVisitor& visitor, 156 const ReferenceVisitor& ref_visitor) 157 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 158 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 159 160 void SweepSystemWeaks(Thread* self) 161 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) LOCKS_EXCLUDED(Locks::heap_bitmap_lock_); 162 163 static mirror::Object* VerifySystemWeakIsLiveCallback(mirror::Object* obj, void* arg) 164 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 165 166 void VerifySystemWeaks() 167 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 168 169 // Verify that an object is live, either in a live bitmap or in the allocation stack. 170 void VerifyIsLive(const mirror::Object* obj) 171 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 172 173 static mirror::Object* MarkObjectCallback(mirror::Object* obj, void* arg) 174 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 175 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 176 177 static void MarkHeapReferenceCallback(mirror::HeapReference<mirror::Object>* ref, void* arg) 178 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 179 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 180 181 static bool HeapReferenceMarkedCallback(mirror::HeapReference<mirror::Object>* ref, void* arg) 182 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 183 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 184 185 static void MarkRootCallback(mirror::Object** root, void* arg, uint32_t thread_id, 186 RootType root_type) 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, uint32_t /*thread_id*/, 191 RootType /*root_type*/) 192 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 193 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 194 195 static void ProcessMarkStackCallback(void* arg) 196 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 197 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 198 199 static void MarkRootParallelCallback(mirror::Object** root, void* arg, uint32_t thread_id, 200 RootType root_type) 201 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 202 203 // Marks an object. 204 void MarkObject(mirror::Object* obj) 205 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 206 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 207 208 Barrier& GetBarrier() { 209 return *gc_barrier_; 210 } 211 212 // Schedules an unmarked object for reference processing. 213 void DelayReferenceReferent(mirror::Class* klass, mirror::Reference* reference) 214 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 215 216 protected: 217 // Returns true if the object has its bit set in the mark bitmap. 218 bool IsMarked(const mirror::Object* object) const; 219 220 static mirror::Object* IsMarkedCallback(mirror::Object* object, void* arg) 221 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 222 223 static void VerifyImageRootVisitor(mirror::Object* root, void* arg) 224 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 225 226 void MarkObjectNonNull(mirror::Object* obj) 227 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 228 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 229 230 // Marks an object atomically, safe to use from multiple threads. 231 void MarkObjectNonNullParallel(mirror::Object* obj); 232 233 // Returns true if we need to add obj to a mark stack. 234 bool MarkObjectParallel(const mirror::Object* obj) NO_THREAD_SAFETY_ANALYSIS; 235 236 // Verify the roots of the heap and print out information related to any invalid roots. 237 // Called in MarkObject, so may we may not hold the mutator lock. 238 void VerifyRoots() 239 NO_THREAD_SAFETY_ANALYSIS; 240 241 // Expand mark stack to 2x its current size. 242 void ExpandMarkStack() EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 243 void ResizeMarkStack(size_t new_size) EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 244 245 // Returns how many threads we should use for the current GC phase based on if we are paused, 246 // whether or not we care about pauses. 247 size_t GetThreadCount(bool paused) const; 248 249 static void VerifyRootCallback(const mirror::Object* root, void* arg, size_t vreg, 250 const StackVisitor *visitor, RootType root_type); 251 252 void VerifyRoot(const mirror::Object* root, size_t vreg, const StackVisitor* visitor, 253 RootType root_type) NO_THREAD_SAFETY_ANALYSIS; 254 255 // Push a single reference on a mark stack. 256 void PushOnMarkStack(mirror::Object* obj); 257 258 // Blackens objects grayed during a garbage collection. 259 void ScanGrayObjects(bool paused, byte minimum_age) 260 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 261 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 262 263 // Recursively blackens objects on the mark stack. 264 void ProcessMarkStack(bool paused) 265 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 266 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 267 268 void ProcessMarkStackParallel(size_t thread_count) 269 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 270 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 271 272 // Used to Get around thread safety annotations. The call is from MarkingPhase and is guarded by 273 // IsExclusiveHeld. 274 void RevokeAllThreadLocalAllocationStacks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 275 276 // Revoke all the thread-local buffers. 277 void RevokeAllThreadLocalBuffers(); 278 279 // Whether or not we count how many of each type of object were scanned. 280 static const bool kCountScannedTypes = false; 281 282 // Current space, we check this space first to avoid searching for the appropriate space for an 283 // object. 284 accounting::ContinuousSpaceBitmap* current_space_bitmap_; 285 // Cache the heap's mark bitmap to prevent having to do 2 loads during slow path marking. 286 accounting::HeapBitmap* mark_bitmap_; 287 288 accounting::ObjectStack* mark_stack_; 289 290 // Immune region, every object inside the immune range is assumed to be marked. 291 ImmuneRegion immune_region_; 292 293 // Parallel finger. 294 AtomicInteger atomic_finger_; 295 // Number of classes scanned, if kCountScannedTypes. 296 AtomicInteger class_count_; 297 // Number of arrays scanned, if kCountScannedTypes. 298 AtomicInteger array_count_; 299 // Number of non-class/arrays scanned, if kCountScannedTypes. 300 AtomicInteger other_count_; 301 AtomicInteger large_object_test_; 302 AtomicInteger large_object_mark_; 303 AtomicInteger overhead_time_; 304 AtomicInteger work_chunks_created_; 305 AtomicInteger work_chunks_deleted_; 306 AtomicInteger reference_count_; 307 AtomicInteger mark_null_count_; 308 AtomicInteger mark_immune_count_; 309 AtomicInteger mark_fastpath_count_; 310 AtomicInteger mark_slowpath_count_; 311 312 std::unique_ptr<Barrier> gc_barrier_; 313 Mutex mark_stack_lock_ ACQUIRED_AFTER(Locks::classlinker_classes_lock_); 314 315 const bool is_concurrent_; 316 317 // Verification. 318 size_t live_stack_freeze_size_; 319 320 std::unique_ptr<MemMap> sweep_array_free_buffer_mem_map_; 321 322 private: 323 friend class AddIfReachesAllocSpaceVisitor; // Used by mod-union table. 324 friend class CardScanTask; 325 friend class CheckBitmapVisitor; 326 friend class CheckReferenceVisitor; 327 friend class art::gc::Heap; 328 friend class MarkObjectVisitor; 329 friend class ModUnionCheckReferences; 330 friend class ModUnionClearCardVisitor; 331 friend class ModUnionReferenceVisitor; 332 friend class ModUnionVisitor; 333 friend class ModUnionTableBitmap; 334 friend class ModUnionTableReferenceCache; 335 friend class ModUnionScanImageRootVisitor; 336 template<bool kUseFinger> friend class MarkStackTask; 337 friend class FifoMarkStackChunk; 338 friend class MarkSweepMarkObjectSlowPath; 339 340 DISALLOW_COPY_AND_ASSIGN(MarkSweep); 341}; 342 343} // namespace collector 344} // namespace gc 345} // namespace art 346 347#endif // ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_ 348