1 /* 2 * Copyright (C) 2013 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_SEMI_SPACE_H_ 18 #define ART_RUNTIME_GC_COLLECTOR_SEMI_SPACE_H_ 19 20 #include <memory> 21 22 #include "base/atomic.h" 23 #include "base/locks.h" 24 #include "base/macros.h" 25 #include "garbage_collector.h" 26 #include "gc/accounting/heap_bitmap.h" 27 #include "gc_root.h" 28 #include "immune_spaces.h" 29 #include "mirror/object_reference.h" 30 #include "offsets.h" 31 32 namespace art { 33 34 class Thread; 35 36 namespace mirror { 37 class Class; 38 class Object; 39 } // namespace mirror 40 41 namespace gc { 42 43 class Heap; 44 45 namespace accounting { 46 template <typename T> class AtomicStack; 47 typedef AtomicStack<mirror::Object> ObjectStack; 48 } // namespace accounting 49 50 namespace space { 51 class ContinuousMemMapAllocSpace; 52 class ContinuousSpace; 53 } // namespace space 54 55 namespace collector { 56 57 class SemiSpace : public GarbageCollector { 58 public: 59 // If true, use remembered sets in the generational mode. 60 static constexpr bool kUseRememberedSet = true; 61 62 explicit SemiSpace(Heap* heap, bool generational = false, const std::string& name_prefix = ""); 63 64 ~SemiSpace() {} 65 66 void RunPhases() override NO_THREAD_SAFETY_ANALYSIS; 67 virtual void InitializePhase(); 68 virtual void MarkingPhase() REQUIRES(Locks::mutator_lock_) 69 REQUIRES(!Locks::heap_bitmap_lock_); 70 virtual void ReclaimPhase() REQUIRES(Locks::mutator_lock_) 71 REQUIRES(!Locks::heap_bitmap_lock_); 72 virtual void FinishPhase() REQUIRES(Locks::mutator_lock_); 73 void MarkReachableObjects() 74 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 75 GcType GetGcType() const override { 76 return kGcTypePartial; 77 } 78 CollectorType GetCollectorType() const override { 79 return generational_ ? kCollectorTypeGSS : kCollectorTypeSS; 80 } 81 82 // Sets which space we will be copying objects to. 83 void SetToSpace(space::ContinuousMemMapAllocSpace* to_space); 84 85 // Set the space where we copy objects from. 86 void SetFromSpace(space::ContinuousMemMapAllocSpace* from_space); 87 88 // Set whether or not we swap the semi spaces in the heap. This needs to be done with mutators 89 // suspended. 90 void SetSwapSemiSpaces(bool swap_semi_spaces) { 91 swap_semi_spaces_ = swap_semi_spaces; 92 } 93 94 // Initializes internal structures. 95 void Init(); 96 97 // Find the default mark bitmap. 98 void FindDefaultMarkBitmap(); 99 100 // Updates obj_ptr if the object has moved. Takes either an ObjectReference or a HeapReference. 101 template<typename CompressedReferenceType> 102 void MarkObject(CompressedReferenceType* obj_ptr) 103 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 104 105 template<typename CompressedReferenceType> 106 void MarkObjectIfNotInToSpace(CompressedReferenceType* obj_ptr) 107 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 108 109 mirror::Object* MarkObject(mirror::Object* root) override 110 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 111 112 void MarkHeapReference(mirror::HeapReference<mirror::Object>* obj_ptr, 113 bool do_atomic_update) override 114 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 115 116 void ScanObject(mirror::Object* obj) 117 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 118 119 void VerifyNoFromSpaceReferences(mirror::Object* obj) 120 REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 121 122 // Marks the root set at the start of a garbage collection. 123 void MarkRoots() 124 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 125 126 // Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie 127 // the image. Mark that portion of the heap as immune. 128 virtual void BindBitmaps() REQUIRES_SHARED(Locks::mutator_lock_) 129 REQUIRES(!Locks::heap_bitmap_lock_); 130 131 void UnBindBitmaps() 132 REQUIRES(Locks::heap_bitmap_lock_); 133 134 void ProcessReferences(Thread* self) REQUIRES(Locks::mutator_lock_) 135 REQUIRES(Locks::mutator_lock_); 136 137 // Sweeps unmarked objects to complete the garbage collection. 138 virtual void Sweep(bool swap_bitmaps) 139 REQUIRES(Locks::heap_bitmap_lock_) 140 REQUIRES_SHARED(Locks::mutator_lock_); 141 142 // Sweeps unmarked objects to complete the garbage collection. 143 void SweepLargeObjects(bool swap_bitmaps) REQUIRES(Locks::heap_bitmap_lock_); 144 145 void SweepSystemWeaks() 146 REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 147 148 void VisitRoots(mirror::Object*** roots, size_t count, const RootInfo& info) override 149 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 150 151 void VisitRoots(mirror::CompressedReference<mirror::Object>** roots, 152 size_t count, 153 const RootInfo& info) override 154 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 155 156 virtual mirror::Object* MarkNonForwardedObject(mirror::Object* obj) 157 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 158 159 // Schedules an unmarked object for reference processing. 160 void DelayReferenceReferent(ObjPtr<mirror::Class> klass, ObjPtr<mirror::Reference> reference) 161 override REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 162 163 protected: 164 // Returns null if the object is not marked, otherwise returns the forwarding address (same as 165 // object for non movable things). 166 mirror::Object* IsMarked(mirror::Object* object) override 167 REQUIRES(Locks::mutator_lock_) 168 REQUIRES_SHARED(Locks::heap_bitmap_lock_); 169 170 bool IsNullOrMarkedHeapReference(mirror::HeapReference<mirror::Object>* object, 171 bool do_atomic_update) override 172 REQUIRES(Locks::mutator_lock_) 173 REQUIRES_SHARED(Locks::heap_bitmap_lock_); 174 175 // Marks or unmarks a large object based on whether or not set is true. If set is true, then we 176 // mark, otherwise we unmark. 177 bool MarkLargeObject(const mirror::Object* obj) 178 REQUIRES(Locks::heap_bitmap_lock_) 179 REQUIRES_SHARED(Locks::mutator_lock_); 180 181 // Expand mark stack to 2x its current size. 182 void ResizeMarkStack(size_t new_size) REQUIRES_SHARED(Locks::mutator_lock_); 183 184 // Returns true if we should sweep the space. 185 virtual bool ShouldSweepSpace(space::ContinuousSpace* space) const; 186 187 // Push an object onto the mark stack. 188 void MarkStackPush(mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_); 189 190 void UpdateAndMarkModUnion() 191 REQUIRES(Locks::heap_bitmap_lock_) 192 REQUIRES_SHARED(Locks::mutator_lock_); 193 194 // Recursively blackens objects on the mark stack. 195 void ProcessMarkStack() override 196 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 197 198 inline mirror::Object* GetForwardingAddressInFromSpace(mirror::Object* obj) const 199 REQUIRES_SHARED(Locks::mutator_lock_); 200 201 // Revoke all the thread-local buffers. 202 void RevokeAllThreadLocalBuffers() override; 203 204 // Current space, we check this space first to avoid searching for the appropriate space for an 205 // object. 206 accounting::ObjectStack* mark_stack_; 207 208 // Every object inside the immune spaces is assumed to be marked. 209 ImmuneSpaces immune_spaces_; 210 211 // If true, the large object space is immune. 212 bool is_large_object_space_immune_; 213 214 // Destination and source spaces (can be any type of ContinuousMemMapAllocSpace which either has 215 // a live bitmap or doesn't). 216 space::ContinuousMemMapAllocSpace* to_space_; 217 // Cached live bitmap as an optimization. 218 accounting::ContinuousSpaceBitmap* to_space_live_bitmap_; 219 space::ContinuousMemMapAllocSpace* from_space_; 220 // Cached mark bitmap as an optimization. 221 accounting::HeapBitmap* mark_bitmap_; 222 223 Thread* self_; 224 225 // When true, the generational mode (promotion and the bump pointer 226 // space only collection) is enabled. TODO: move these to a new file 227 // as a new garbage collector? 228 const bool generational_; 229 230 // Used for the generational mode. the end/top of the bump 231 // pointer space at the end of the last collection. 232 uint8_t* last_gc_to_space_end_; 233 234 // Used for the generational mode. During a collection, keeps track 235 // of how many bytes of objects have been copied so far from the 236 // bump pointer space to the non-moving space. 237 uint64_t bytes_promoted_; 238 239 // Used for the generational mode. Keeps track of how many bytes of 240 // objects have been copied so far from the bump pointer space to 241 // the non-moving space, since the last whole heap collection. 242 uint64_t bytes_promoted_since_last_whole_heap_collection_; 243 244 // Used for the generational mode. Keeps track of how many bytes of 245 // large objects were allocated at the last whole heap collection. 246 uint64_t large_object_bytes_allocated_at_last_whole_heap_collection_; 247 248 // Used for generational mode. When true, we only collect the from_space_. 249 bool collect_from_space_only_; 250 251 // The space which we are promoting into, only used for GSS. 252 space::ContinuousMemMapAllocSpace* promo_dest_space_; 253 254 // The space which we copy to if the to_space_ is full. 255 space::ContinuousMemMapAllocSpace* fallback_space_; 256 257 // How many objects and bytes we moved, used so that we don't need to Get the size of the 258 // to_space_ when calculating how many objects and bytes we freed. 259 size_t bytes_moved_; 260 size_t objects_moved_; 261 262 // How many bytes we avoided dirtying. 263 size_t saved_bytes_; 264 265 // The name of the collector. 266 std::string collector_name_; 267 268 // Used for the generational mode. The default interval of the whole 269 // heap collection. If N, the whole heap collection occurs every N 270 // collections. 271 static constexpr int kDefaultWholeHeapCollectionInterval = 5; 272 273 // Whether or not we swap the semi spaces in the heap during the marking phase. 274 bool swap_semi_spaces_; 275 276 private: 277 class BitmapSetSlowPathVisitor; 278 class MarkObjectVisitor; 279 class VerifyNoFromSpaceReferencesVisitor; 280 DISALLOW_IMPLICIT_CONSTRUCTORS(SemiSpace); 281 }; 282 283 } // namespace collector 284 } // namespace gc 285 } // namespace art 286 287 #endif // ART_RUNTIME_GC_COLLECTOR_SEMI_SPACE_H_ 288
