mark_sweep.h revision ef7d42fca18c16fbaf103822ad16f23246e2905d
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 "atomic.h" 21#include "barrier.h" 22#include "base/macros.h" 23#include "base/mutex.h" 24#include "garbage_collector.h" 25#include "offsets.h" 26#include "root_visitor.h" 27#include "UniquePtr.h" 28 29namespace art { 30 31namespace mirror { 32 class Class; 33 class Object; 34 template<class T> class ObjectArray; 35} // namespace mirror 36 37class StackVisitor; 38class Thread; 39 40namespace gc { 41 42namespace accounting { 43 template <typename T> class AtomicStack; 44 class MarkIfReachesAllocspaceVisitor; 45 class ModUnionClearCardVisitor; 46 class ModUnionVisitor; 47 class ModUnionTableBitmap; 48 class MarkStackChunk; 49 typedef AtomicStack<mirror::Object*> ObjectStack; 50 class SpaceBitmap; 51} // namespace accounting 52 53namespace space { 54 class ContinuousSpace; 55} // namespace space 56 57class Heap; 58 59namespace collector { 60 61class MarkSweep : public GarbageCollector { 62 public: 63 explicit MarkSweep(Heap* heap, bool is_concurrent, const std::string& name_prefix = ""); 64 65 ~MarkSweep() {} 66 67 virtual void InitializePhase(); 68 virtual bool IsConcurrent() const; 69 virtual bool HandleDirtyObjectsPhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_); 70 virtual void MarkingPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 71 virtual void ReclaimPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 72 virtual void FinishPhase() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 73 virtual void MarkReachableObjects() 74 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 75 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 76 virtual GcType GetGcType() const { 77 return kGcTypeFull; 78 } 79 80 // Initializes internal structures. 81 void Init(); 82 83 // Find the default mark bitmap. 84 void FindDefaultMarkBitmap(); 85 86 // Marks the root set at the start of a garbage collection. 87 void MarkRoots() 88 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 89 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 90 91 void MarkNonThreadRoots() 92 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 93 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 94 95 void MarkConcurrentRoots() 96 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 97 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 98 99 void MarkRootsCheckpoint(Thread* self) 100 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 101 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 102 103 // Builds a mark stack and recursively mark until it empties. 104 void RecursiveMark() 105 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 106 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 107 108 // Make a space immune, immune spaces have all live objects marked - that is the mark and 109 // live bitmaps are bound together. 110 void ImmuneSpace(space::ContinuousSpace* space) 111 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 112 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 113 114 bool IsImmuneSpace(const space::ContinuousSpace* space) const; 115 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 116 117 // Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie 118 // the image. Mark that portion of the heap as immune. 119 virtual void BindBitmaps() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 120 121 // Builds a mark stack with objects on dirty cards and recursively mark until it empties. 122 void RecursiveMarkDirtyObjects(bool paused, byte minimum_age) 123 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 124 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 125 126 // Remarks the root set after completing the concurrent mark. 127 void ReMarkRoots() 128 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 129 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 130 131 void ProcessReferences(Thread* self) 132 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 133 134 // Update and mark references from immune spaces. 135 virtual void UpdateAndMarkModUnion() 136 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 137 138 // Sweeps unmarked objects to complete the garbage collection. 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 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 // TODO: enable thread safety analysis when in use by multiple worker threads. 154 template <typename MarkVisitor> 155 void ScanObjectVisit(mirror::Object* obj, const MarkVisitor& visitor) 156 NO_THREAD_SAFETY_ANALYSIS; 157 158 // Everything inside the immune range is assumed to be marked. 159 void SetImmuneRange(mirror::Object* begin, mirror::Object* end); 160 161 void SweepSystemWeaks() 162 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, 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 template <typename Visitor> 175 static void VisitObjectReferences(mirror::Object* obj, const Visitor& visitor, bool visit_class) 176 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, 177 Locks::mutator_lock_); 178 179 static mirror::Object* RecursiveMarkObjectCallback(mirror::Object* obj, void* arg) 180 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 181 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 182 183 static mirror::Object* MarkRootCallback(mirror::Object* root, void* arg) 184 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 185 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 186 187 static mirror::Object* MarkRootParallelCallback(mirror::Object* root, void* arg); 188 189 // Marks an object. 190 void MarkObject(const mirror::Object* obj) 191 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 192 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 193 194 void MarkRoot(const mirror::Object* obj) 195 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 196 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 197 198 Barrier& GetBarrier() { 199 return *gc_barrier_; 200 } 201 202 protected: 203 // Returns true if the object has its bit set in the mark bitmap. 204 bool IsMarked(const mirror::Object* object) const; 205 206 static mirror::Object* IsMarkedCallback(mirror::Object* object, void* arg) 207 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 208 209 static void VerifyImageRootVisitor(mirror::Object* root, void* arg) 210 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, 211 Locks::mutator_lock_); 212 213 void MarkObjectNonNull(const mirror::Object* obj) 214 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 215 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 216 217 // Unmarks an object by clearing the bit inside of the corresponding bitmap, or if it is in a 218 // space set, removing the object from the set. 219 void UnMarkObjectNonNull(const mirror::Object* obj) 220 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) 221 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 222 223 // Mark the vm thread roots. 224 virtual void MarkThreadRoots(Thread* self) 225 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 226 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 227 228 // Marks an object atomically, safe to use from multiple threads. 229 void MarkObjectNonNullParallel(const mirror::Object* obj); 230 231 // Marks or unmarks a large object based on whether or not set is true. If set is true, then we 232 // mark, otherwise we unmark. 233 bool MarkLargeObject(const mirror::Object* obj, bool set) 234 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_); 235 236 // Returns true if we need to add obj to a mark stack. 237 bool MarkObjectParallel(const mirror::Object* obj) NO_THREAD_SAFETY_ANALYSIS; 238 239 // Verify the roots of the heap and print out information related to any invalid roots. 240 // Called in MarkObject, so may we may not hold the mutator lock. 241 void VerifyRoots() 242 NO_THREAD_SAFETY_ANALYSIS; 243 244 // Expand mark stack to 2x its current size. 245 void ExpandMarkStack() EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 246 void ResizeMarkStack(size_t new_size) EXCLUSIVE_LOCKS_REQUIRED(mark_stack_lock_); 247 248 // Returns how many threads we should use for the current GC phase based on if we are paused, 249 // whether or not we care about pauses. 250 size_t GetThreadCount(bool paused) const; 251 252 // Returns true if an object is inside of the immune region (assumed to be marked). 253 bool IsImmune(const mirror::Object* obj) const ALWAYS_INLINE { 254 return obj >= immune_begin_ && obj < immune_end_; 255 } 256 257 static void VerifyRootCallback(const mirror::Object* root, void* arg, size_t vreg, 258 const StackVisitor *visitor); 259 260 void VerifyRoot(const mirror::Object* root, size_t vreg, const StackVisitor* visitor) 261 NO_THREAD_SAFETY_ANALYSIS; 262 263 template <typename Visitor> 264 static void VisitInstanceFieldsReferences(mirror::Class* klass, mirror::Object* obj, 265 const Visitor& visitor) 266 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 267 268 // Visit the header, static field references, and interface pointers of a class object. 269 template <typename Visitor> 270 static void VisitClassReferences(mirror::Class* klass, mirror::Object* obj, 271 const Visitor& visitor) 272 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 273 274 template <typename Visitor> 275 static void VisitStaticFieldsReferences(mirror::Class* klass, const Visitor& visitor) 276 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 277 278 template <typename Visitor> 279 static void VisitFieldsReferences(mirror::Object* obj, uint32_t ref_offsets, bool is_static, 280 const Visitor& visitor) 281 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 282 283 // Visit all of the references in an object array. 284 template <typename Visitor> 285 static void VisitObjectArrayReferences(mirror::ObjectArray<mirror::Object>* array, 286 const Visitor& visitor) 287 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 288 289 // Visits the header and field references of a data object. 290 template <typename Visitor> 291 static void VisitOtherReferences(mirror::Class* klass, mirror::Object* obj, 292 const Visitor& visitor) 293 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) { 294 return VisitInstanceFieldsReferences(klass, obj, visitor); 295 } 296 297 // Blackens objects grayed during a garbage collection. 298 void ScanGrayObjects(bool paused, byte minimum_age) 299 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 300 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 301 302 // Schedules an unmarked object for reference processing. 303 void DelayReferenceReferent(mirror::Class* klass, mirror::Object* reference) 304 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 305 306 // Recursively blackens objects on the mark stack. 307 void ProcessMarkStack(bool paused) 308 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 309 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 310 311 void ProcessMarkStackParallel(size_t thread_count) 312 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 313 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 314 315 void EnqueueFinalizerReferences(mirror::Object** ref) 316 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 317 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 318 319 void PreserveSomeSoftReferences(mirror::Object** ref) 320 EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) 321 SHARED_LOCKS_REQUIRED(Locks::mutator_lock_); 322 323 void ClearWhiteReferences(mirror::Object** list) 324 SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 325 326 // Whether or not we count how many of each type of object were scanned. 327 static const bool kCountScannedTypes = false; 328 329 // Current space, we check this space first to avoid searching for the appropriate space for an 330 // object. 331 accounting::SpaceBitmap* current_mark_bitmap_; 332 333 accounting::ObjectStack* mark_stack_; 334 335 // Immune range, every object inside the immune range is assumed to be marked. 336 mirror::Object* immune_begin_; 337 mirror::Object* immune_end_; 338 339 // Parallel finger. 340 AtomicInteger atomic_finger_; 341 // Number of classes scanned, if kCountScannedTypes. 342 AtomicInteger class_count_; 343 // Number of arrays scanned, if kCountScannedTypes. 344 AtomicInteger array_count_; 345 // Number of non-class/arrays scanned, if kCountScannedTypes. 346 AtomicInteger other_count_; 347 AtomicInteger large_object_test_; 348 AtomicInteger large_object_mark_; 349 AtomicInteger classes_marked_; 350 AtomicInteger overhead_time_; 351 AtomicInteger work_chunks_created_; 352 AtomicInteger work_chunks_deleted_; 353 AtomicInteger reference_count_; 354 355 // Verification. 356 size_t live_stack_freeze_size_; 357 358 UniquePtr<Barrier> gc_barrier_; 359 Mutex large_object_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER; 360 Mutex mark_stack_lock_ ACQUIRED_AFTER(Locks::classlinker_classes_lock_); 361 362 const bool is_concurrent_; 363 364 private: 365 friend class AddIfReachesAllocSpaceVisitor; // Used by mod-union table. 366 friend class CardScanTask; 367 friend class CheckBitmapVisitor; 368 friend class CheckReferenceVisitor; 369 friend class art::gc::Heap; 370 friend class InternTableEntryIsUnmarked; 371 friend class MarkIfReachesAllocspaceVisitor; 372 friend class ModUnionCheckReferences; 373 friend class ModUnionClearCardVisitor; 374 friend class ModUnionReferenceVisitor; 375 friend class ModUnionVisitor; 376 friend class ModUnionTableBitmap; 377 friend class ModUnionTableReferenceCache; 378 friend class ModUnionScanImageRootVisitor; 379 friend class ScanBitmapVisitor; 380 friend class ScanImageRootVisitor; 381 template<bool kUseFinger> friend class MarkStackTask; 382 friend class FifoMarkStackChunk; 383 384 DISALLOW_COPY_AND_ASSIGN(MarkSweep); 385}; 386 387} // namespace collector 388} // namespace gc 389} // namespace art 390 391#endif // ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_ 392