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