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_SPACE_BUMP_POINTER_SPACE_H_ 18 #define ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_H_ 19 20 #include "space.h" 21 22 namespace art { 23 24 namespace mirror { 25 class Object; 26 } 27 28 namespace gc { 29 30 namespace collector { 31 class MarkSweep; 32 } // namespace collector 33 34 namespace space { 35 36 // A bump pointer space allocates by incrementing a pointer, it doesn't provide a free 37 // implementation as its intended to be evacuated. 38 class BumpPointerSpace FINAL : public ContinuousMemMapAllocSpace { 39 public: 40 typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg); 41 42 SpaceType GetType() const OVERRIDE { 43 return kSpaceTypeBumpPointerSpace; 44 } 45 46 // Create a bump pointer space with the requested sizes. The requested base address is not 47 // guaranteed to be granted, if it is required, the caller should call Begin on the returned 48 // space to confirm the request was granted. 49 static BumpPointerSpace* Create(const std::string& name, size_t capacity, uint8_t* requested_begin); 50 static BumpPointerSpace* CreateFromMemMap(const std::string& name, MemMap* mem_map); 51 52 // Allocate num_bytes, returns null if the space is full. 53 mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated, 54 size_t* usable_size, size_t* bytes_tl_bulk_allocated) OVERRIDE; 55 // Thread-unsafe allocation for when mutators are suspended, used by the semispace collector. 56 mirror::Object* AllocThreadUnsafe(Thread* self, size_t num_bytes, size_t* bytes_allocated, 57 size_t* usable_size, size_t* bytes_tl_bulk_allocated) 58 OVERRIDE REQUIRES(Locks::mutator_lock_); 59 60 mirror::Object* AllocNonvirtual(size_t num_bytes); 61 mirror::Object* AllocNonvirtualWithoutAccounting(size_t num_bytes); 62 63 // Return the storage space required by obj. 64 size_t AllocationSize(mirror::Object* obj, size_t* usable_size) OVERRIDE 65 REQUIRES_SHARED(Locks::mutator_lock_) { 66 return AllocationSizeNonvirtual(obj, usable_size); 67 } 68 69 // NOPS unless we support free lists. 70 size_t Free(Thread*, mirror::Object*) OVERRIDE { 71 return 0; 72 } 73 74 size_t FreeList(Thread*, size_t, mirror::Object**) OVERRIDE { 75 return 0; 76 } 77 78 size_t AllocationSizeNonvirtual(mirror::Object* obj, size_t* usable_size) 79 REQUIRES_SHARED(Locks::mutator_lock_); 80 81 // Removes the fork time growth limit on capacity, allowing the application to allocate up to the 82 // maximum reserved size of the heap. 83 void ClearGrowthLimit() { 84 growth_end_ = Limit(); 85 } 86 87 // Override capacity so that we only return the possibly limited capacity 88 size_t Capacity() const { 89 return growth_end_ - begin_; 90 } 91 92 // The total amount of memory reserved for the space. 93 size_t NonGrowthLimitCapacity() const { 94 return GetMemMap()->Size(); 95 } 96 97 accounting::ContinuousSpaceBitmap* GetLiveBitmap() const OVERRIDE { 98 return nullptr; 99 } 100 101 accounting::ContinuousSpaceBitmap* GetMarkBitmap() const OVERRIDE { 102 return nullptr; 103 } 104 105 // Reset the space to empty. 106 void Clear() OVERRIDE REQUIRES(!block_lock_); 107 108 void Dump(std::ostream& os) const; 109 110 size_t RevokeThreadLocalBuffers(Thread* thread) REQUIRES(!block_lock_); 111 size_t RevokeAllThreadLocalBuffers() 112 REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !block_lock_); 113 void AssertThreadLocalBuffersAreRevoked(Thread* thread) REQUIRES(!block_lock_); 114 void AssertAllThreadLocalBuffersAreRevoked() 115 REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !block_lock_); 116 117 uint64_t GetBytesAllocated() REQUIRES_SHARED(Locks::mutator_lock_) 118 REQUIRES(!*Locks::runtime_shutdown_lock_, !*Locks::thread_list_lock_, !block_lock_); 119 uint64_t GetObjectsAllocated() REQUIRES_SHARED(Locks::mutator_lock_) 120 REQUIRES(!*Locks::runtime_shutdown_lock_, !*Locks::thread_list_lock_, !block_lock_); 121 bool IsEmpty() const { 122 return Begin() == End(); 123 } 124 125 bool CanMoveObjects() const OVERRIDE { 126 return true; 127 } 128 129 bool Contains(const mirror::Object* obj) const { 130 const uint8_t* byte_obj = reinterpret_cast<const uint8_t*>(obj); 131 return byte_obj >= Begin() && byte_obj < End(); 132 } 133 134 // TODO: Change this? Mainly used for compacting to a particular region of memory. 135 BumpPointerSpace(const std::string& name, uint8_t* begin, uint8_t* limit); 136 137 // Return the object which comes after obj, while ensuring alignment. 138 static mirror::Object* GetNextObject(mirror::Object* obj) 139 REQUIRES_SHARED(Locks::mutator_lock_); 140 141 // Allocate a new TLAB, returns false if the allocation failed. 142 bool AllocNewTlab(Thread* self, size_t bytes) REQUIRES(!block_lock_); 143 144 BumpPointerSpace* AsBumpPointerSpace() OVERRIDE { 145 return this; 146 } 147 148 // Go through all of the blocks and visit the continuous objects. 149 template <typename Visitor> 150 ALWAYS_INLINE void Walk(Visitor&& visitor) 151 REQUIRES_SHARED(Locks::mutator_lock_) 152 REQUIRES(!block_lock_); 153 154 accounting::ContinuousSpaceBitmap::SweepCallback* GetSweepCallback() OVERRIDE; 155 156 // Record objects / bytes freed. 157 void RecordFree(int32_t objects, int32_t bytes) { 158 objects_allocated_.FetchAndSubSequentiallyConsistent(objects); 159 bytes_allocated_.FetchAndSubSequentiallyConsistent(bytes); 160 } 161 162 void LogFragmentationAllocFailure(std::ostream& os, size_t failed_alloc_bytes) OVERRIDE 163 REQUIRES_SHARED(Locks::mutator_lock_); 164 165 // Object alignment within the space. 166 static constexpr size_t kAlignment = 8; 167 168 protected: 169 BumpPointerSpace(const std::string& name, MemMap* mem_map); 170 171 // Allocate a raw block of bytes. 172 uint8_t* AllocBlock(size_t bytes) REQUIRES(block_lock_); 173 void RevokeThreadLocalBuffersLocked(Thread* thread) REQUIRES(block_lock_); 174 175 // The main block is an unbounded block where objects go when there are no other blocks. This 176 // enables us to maintain tightly packed objects when you are not using thread local buffers for 177 // allocation. The main block starts at the space Begin(). 178 void UpdateMainBlock() REQUIRES(block_lock_); 179 180 uint8_t* growth_end_; 181 AtomicInteger objects_allocated_; // Accumulated from revoked thread local regions. 182 AtomicInteger bytes_allocated_; // Accumulated from revoked thread local regions. 183 Mutex block_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER; 184 // The objects at the start of the space are stored in the main block. The main block doesn't 185 // have a header, this lets us walk empty spaces which are mprotected. 186 size_t main_block_size_ GUARDED_BY(block_lock_); 187 // The number of blocks in the space, if it is 0 then the space has one long continuous block 188 // which doesn't have an updated header. 189 size_t num_blocks_ GUARDED_BY(block_lock_); 190 191 private: 192 struct BlockHeader { 193 size_t size_; // Size of the block in bytes, does not include the header. 194 size_t unused_; // Ensures alignment of kAlignment. 195 }; 196 197 static_assert(sizeof(BlockHeader) % kAlignment == 0, 198 "continuous block must be kAlignment aligned"); 199 200 friend class collector::MarkSweep; 201 DISALLOW_COPY_AND_ASSIGN(BumpPointerSpace); 202 }; 203 204 } // namespace space 205 } // namespace gc 206 } // namespace art 207 208 #endif // ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_H_ 209
