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 "atomic.h" 23 #include "base/macros.h" 24 #include "base/mutex.h" 25 #include "garbage_collector.h" 26 #include "gc_root.h" 27 #include "gc/accounting/heap_bitmap.h" 28 #include "immune_spaces.h" 29 #include "mirror/object_reference.h" 30 #include "object_callbacks.h" 31 #include "offsets.h" 32 33 namespace art { 34 35 class Thread; 36 37 namespace mirror { 38 class Class; 39 class Object; 40 } // namespace mirror 41 42 namespace gc { 43 44 class Heap; 45 46 namespace accounting { 47 template <typename T> class AtomicStack; 48 typedef AtomicStack<mirror::Object> ObjectStack; 49 } // namespace accounting 50 51 namespace space { 52 class ContinuousMemMapAllocSpace; 53 class ContinuousSpace; 54 } // namespace space 55 56 namespace collector { 57 58 class SemiSpace : public GarbageCollector { 59 public: 60 // If true, use remembered sets in the generational mode. 61 static constexpr bool kUseRememberedSet = true; 62 63 explicit SemiSpace(Heap* heap, bool generational = false, const std::string& name_prefix = ""); 64 65 ~SemiSpace() {} 66 67 virtual void RunPhases() OVERRIDE NO_THREAD_SAFETY_ANALYSIS; 68 virtual void InitializePhase(); 69 virtual void MarkingPhase() REQUIRES(Locks::mutator_lock_) 70 REQUIRES(!Locks::heap_bitmap_lock_); 71 virtual void ReclaimPhase() REQUIRES(Locks::mutator_lock_) 72 REQUIRES(!Locks::heap_bitmap_lock_); 73 virtual void FinishPhase() REQUIRES(Locks::mutator_lock_); 74 void MarkReachableObjects() 75 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 76 virtual GcType GetGcType() const OVERRIDE { 77 return kGcTypePartial; 78 } 79 virtual CollectorType GetCollectorType() const OVERRIDE { 80 return generational_ ? kCollectorTypeGSS : kCollectorTypeSS; 81 } 82 83 // Sets which space we will be copying objects to. 84 void SetToSpace(space::ContinuousMemMapAllocSpace* to_space); 85 86 // Set the space where we copy objects from. 87 void SetFromSpace(space::ContinuousMemMapAllocSpace* from_space); 88 89 // Set whether or not we swap the semi spaces in the heap. This needs to be done with mutators 90 // suspended. 91 void SetSwapSemiSpaces(bool swap_semi_spaces) { 92 swap_semi_spaces_ = swap_semi_spaces; 93 } 94 95 // Initializes internal structures. 96 void Init(); 97 98 // Find the default mark bitmap. 99 void FindDefaultMarkBitmap(); 100 101 // Updates obj_ptr if the object has moved. 102 template<bool kPoisonReferences> 103 void MarkObject(mirror::ObjectReference<kPoisonReferences, mirror::Object>* obj_ptr) 104 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 105 106 template<bool kPoisonReferences> 107 void MarkObjectIfNotInToSpace(mirror::ObjectReference<kPoisonReferences, mirror::Object>* obj_ptr) 108 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 109 110 virtual mirror::Object* MarkObject(mirror::Object* root) OVERRIDE 111 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 112 113 virtual void MarkHeapReference(mirror::HeapReference<mirror::Object>* obj_ptr) 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 SHARED_REQUIRES(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() SHARED_REQUIRES(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 SHARED_REQUIRES(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 SHARED_REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 147 148 virtual void VisitRoots(mirror::Object*** roots, size_t count, const RootInfo& info) OVERRIDE 149 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 150 151 virtual void VisitRoots(mirror::CompressedReference<mirror::Object>** roots, size_t count, 152 const RootInfo& info) OVERRIDE 153 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 154 155 virtual mirror::Object* MarkNonForwardedObject(mirror::Object* obj) 156 REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 157 158 // Schedules an unmarked object for reference processing. 159 void DelayReferenceReferent(mirror::Class* klass, mirror::Reference* reference) 160 SHARED_REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_); 161 162 protected: 163 // Returns null if the object is not marked, otherwise returns the forwarding address (same as 164 // object for non movable things). 165 virtual mirror::Object* IsMarked(mirror::Object* object) OVERRIDE 166 REQUIRES(Locks::mutator_lock_) 167 SHARED_REQUIRES(Locks::heap_bitmap_lock_); 168 169 virtual bool IsMarkedHeapReference(mirror::HeapReference<mirror::Object>* object) OVERRIDE 170 REQUIRES(Locks::mutator_lock_) 171 SHARED_REQUIRES(Locks::heap_bitmap_lock_); 172 173 // Marks or unmarks a large object based on whether or not set is true. If set is true, then we 174 // mark, otherwise we unmark. 175 bool MarkLargeObject(const mirror::Object* obj) 176 REQUIRES(Locks::heap_bitmap_lock_) 177 SHARED_REQUIRES(Locks::mutator_lock_); 178 179 // Expand mark stack to 2x its current size. 180 void ResizeMarkStack(size_t new_size) SHARED_REQUIRES(Locks::mutator_lock_); 181 182 // Returns true if we should sweep the space. 183 virtual bool ShouldSweepSpace(space::ContinuousSpace* space) const; 184 185 // Push an object onto the mark stack. 186 void MarkStackPush(mirror::Object* obj) SHARED_REQUIRES(Locks::mutator_lock_); 187 188 void UpdateAndMarkModUnion() 189 REQUIRES(Locks::heap_bitmap_lock_) 190 SHARED_REQUIRES(Locks::mutator_lock_); 191 192 // Recursively blackens objects on the mark stack. 193 void ProcessMarkStack() 194 REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_); 195 196 inline mirror::Object* GetForwardingAddressInFromSpace(mirror::Object* obj) const 197 SHARED_REQUIRES(Locks::mutator_lock_); 198 199 // Revoke all the thread-local buffers. 200 void RevokeAllThreadLocalBuffers(); 201 202 // Current space, we check this space first to avoid searching for the appropriate space for an 203 // object. 204 accounting::ObjectStack* mark_stack_; 205 206 // Every object inside the immune spaces is assumed to be marked. 207 ImmuneSpaces immune_spaces_; 208 209 // If true, the large object space is immune. 210 bool is_large_object_space_immune_; 211 212 // Destination and source spaces (can be any type of ContinuousMemMapAllocSpace which either has 213 // a live bitmap or doesn't). 214 space::ContinuousMemMapAllocSpace* to_space_; 215 // Cached live bitmap as an optimization. 216 accounting::ContinuousSpaceBitmap* to_space_live_bitmap_; 217 space::ContinuousMemMapAllocSpace* from_space_; 218 // Cached mark bitmap as an optimization. 219 accounting::HeapBitmap* mark_bitmap_; 220 221 Thread* self_; 222 223 // When true, the generational mode (promotion and the bump pointer 224 // space only collection) is enabled. TODO: move these to a new file 225 // as a new garbage collector? 226 const bool generational_; 227 228 // Used for the generational mode. the end/top of the bump 229 // pointer space at the end of the last collection. 230 uint8_t* last_gc_to_space_end_; 231 232 // Used for the generational mode. During a collection, keeps track 233 // of how many bytes of objects have been copied so far from the 234 // bump pointer space to the non-moving space. 235 uint64_t bytes_promoted_; 236 237 // Used for the generational mode. Keeps track of how many bytes of 238 // objects have been copied so far from the bump pointer space to 239 // the non-moving space, since the last whole heap collection. 240 uint64_t bytes_promoted_since_last_whole_heap_collection_; 241 242 // Used for the generational mode. Keeps track of how many bytes of 243 // large objects were allocated at the last whole heap collection. 244 uint64_t large_object_bytes_allocated_at_last_whole_heap_collection_; 245 246 // Used for generational mode. When true, we only collect the from_space_. 247 bool collect_from_space_only_; 248 249 // The space which we are promoting into, only used for GSS. 250 space::ContinuousMemMapAllocSpace* promo_dest_space_; 251 252 // The space which we copy to if the to_space_ is full. 253 space::ContinuousMemMapAllocSpace* fallback_space_; 254 255 // How many objects and bytes we moved, used so that we don't need to Get the size of the 256 // to_space_ when calculating how many objects and bytes we freed. 257 size_t bytes_moved_; 258 size_t objects_moved_; 259 260 // How many bytes we avoided dirtying. 261 size_t saved_bytes_; 262 263 // The name of the collector. 264 std::string collector_name_; 265 266 // Used for the generational mode. The default interval of the whole 267 // heap collection. If N, the whole heap collection occurs every N 268 // collections. 269 static constexpr int kDefaultWholeHeapCollectionInterval = 5; 270 271 // Whether or not we swap the semi spaces in the heap during the marking phase. 272 bool swap_semi_spaces_; 273 274 private: 275 class BitmapSetSlowPathVisitor; 276 class MarkObjectVisitor; 277 class VerifyNoFromSpaceReferencesVisitor; 278 DISALLOW_IMPLICIT_CONSTRUCTORS(SemiSpace); 279 }; 280 281 } // namespace collector 282 } // namespace gc 283 } // namespace art 284 285 #endif // ART_RUNTIME_GC_COLLECTOR_SEMI_SPACE_H_ 286
