/* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "large_object_space.h" #include #include #include #include "base/macros.h" #include "base/memory_tool.h" #include "base/mutex-inl.h" #include "base/os.h" #include "base/stl_util.h" #include "gc/accounting/heap_bitmap-inl.h" #include "gc/accounting/space_bitmap-inl.h" #include "gc/heap.h" #include "image.h" #include "mirror/object-readbarrier-inl.h" #include "scoped_thread_state_change-inl.h" #include "space-inl.h" #include "thread-current-inl.h" namespace art { namespace gc { namespace space { class MemoryToolLargeObjectMapSpace final : public LargeObjectMapSpace { public: explicit MemoryToolLargeObjectMapSpace(const std::string& name) : LargeObjectMapSpace(name) { } ~MemoryToolLargeObjectMapSpace() override { // Historical note: We were deleting large objects to keep Valgrind happy if there were // any large objects such as Dex cache arrays which aren't freed since they are held live // by the class linker. } mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated, size_t* usable_size, size_t* bytes_tl_bulk_allocated) override { mirror::Object* obj = LargeObjectMapSpace::Alloc(self, num_bytes + kMemoryToolRedZoneBytes * 2, bytes_allocated, usable_size, bytes_tl_bulk_allocated); mirror::Object* object_without_rdz = reinterpret_cast( reinterpret_cast(obj) + kMemoryToolRedZoneBytes); MEMORY_TOOL_MAKE_NOACCESS(reinterpret_cast(obj), kMemoryToolRedZoneBytes); MEMORY_TOOL_MAKE_NOACCESS( reinterpret_cast(object_without_rdz) + num_bytes, kMemoryToolRedZoneBytes); if (usable_size != nullptr) { *usable_size = num_bytes; // Since we have redzones, shrink the usable size. } return object_without_rdz; } size_t AllocationSize(mirror::Object* obj, size_t* usable_size) override { return LargeObjectMapSpace::AllocationSize(ObjectWithRedzone(obj), usable_size); } bool IsZygoteLargeObject(Thread* self, mirror::Object* obj) const override { return LargeObjectMapSpace::IsZygoteLargeObject(self, ObjectWithRedzone(obj)); } size_t Free(Thread* self, mirror::Object* obj) override { mirror::Object* object_with_rdz = ObjectWithRedzone(obj); MEMORY_TOOL_MAKE_UNDEFINED(object_with_rdz, AllocationSize(obj, nullptr)); return LargeObjectMapSpace::Free(self, object_with_rdz); } bool Contains(const mirror::Object* obj) const override { return LargeObjectMapSpace::Contains(ObjectWithRedzone(obj)); } private: static const mirror::Object* ObjectWithRedzone(const mirror::Object* obj) { return reinterpret_cast( reinterpret_cast(obj) - kMemoryToolRedZoneBytes); } static mirror::Object* ObjectWithRedzone(mirror::Object* obj) { return reinterpret_cast( reinterpret_cast(obj) - kMemoryToolRedZoneBytes); } static constexpr size_t kMemoryToolRedZoneBytes = kPageSize; }; void LargeObjectSpace::SwapBitmaps() { std::swap(live_bitmap_, mark_bitmap_); // Preserve names to get more descriptive diagnostics. std::string temp_name = live_bitmap_.GetName(); live_bitmap_.SetName(mark_bitmap_.GetName()); mark_bitmap_.SetName(temp_name); } LargeObjectSpace::LargeObjectSpace(const std::string& name, uint8_t* begin, uint8_t* end, const char* lock_name) : DiscontinuousSpace(name, kGcRetentionPolicyAlwaysCollect), lock_(lock_name, kAllocSpaceLock), num_bytes_allocated_(0), num_objects_allocated_(0), total_bytes_allocated_(0), total_objects_allocated_(0), begin_(begin), end_(end) { } void LargeObjectSpace::CopyLiveToMarked() { mark_bitmap_.CopyFrom(&live_bitmap_); } LargeObjectMapSpace::LargeObjectMapSpace(const std::string& name) : LargeObjectSpace(name, nullptr, nullptr, "large object map space lock") {} LargeObjectMapSpace* LargeObjectMapSpace::Create(const std::string& name) { if (Runtime::Current()->IsRunningOnMemoryTool()) { return new MemoryToolLargeObjectMapSpace(name); } else { return new LargeObjectMapSpace(name); } } mirror::Object* LargeObjectMapSpace::Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated, size_t* usable_size, size_t* bytes_tl_bulk_allocated) { std::string error_msg; MemMap mem_map = MemMap::MapAnonymous("large object space allocation", num_bytes, PROT_READ | PROT_WRITE, /*low_4gb=*/ true, &error_msg); if (UNLIKELY(!mem_map.IsValid())) { LOG(WARNING) << "Large object allocation failed: " << error_msg; return nullptr; } mirror::Object* const obj = reinterpret_cast(mem_map.Begin()); const size_t allocation_size = mem_map.BaseSize(); MutexLock mu(self, lock_); large_objects_.Put(obj, LargeObject {std::move(mem_map), false /* not zygote */}); DCHECK(bytes_allocated != nullptr); if (begin_ == nullptr || begin_ > reinterpret_cast(obj)) { begin_ = reinterpret_cast(obj); } end_ = std::max(end_, reinterpret_cast(obj) + allocation_size); *bytes_allocated = allocation_size; if (usable_size != nullptr) { *usable_size = allocation_size; } DCHECK(bytes_tl_bulk_allocated != nullptr); *bytes_tl_bulk_allocated = allocation_size; num_bytes_allocated_ += allocation_size; total_bytes_allocated_ += allocation_size; ++num_objects_allocated_; ++total_objects_allocated_; return obj; } bool LargeObjectMapSpace::IsZygoteLargeObject(Thread* self, mirror::Object* obj) const { MutexLock mu(self, lock_); auto it = large_objects_.find(obj); CHECK(it != large_objects_.end()); return it->second.is_zygote; } void LargeObjectMapSpace::SetAllLargeObjectsAsZygoteObjects(Thread* self, bool set_mark_bit) { MutexLock mu(self, lock_); for (auto& pair : large_objects_) { pair.second.is_zygote = true; if (set_mark_bit) { bool success = pair.first->AtomicSetMarkBit(0, 1); CHECK(success); } } } size_t LargeObjectMapSpace::Free(Thread* self, mirror::Object* ptr) { MutexLock mu(self, lock_); auto it = large_objects_.find(ptr); if (UNLIKELY(it == large_objects_.end())) { ScopedObjectAccess soa(self); Runtime::Current()->GetHeap()->DumpSpaces(LOG_STREAM(FATAL_WITHOUT_ABORT)); LOG(FATAL) << "Attempted to free large object " << ptr << " which was not live"; } const size_t map_size = it->second.mem_map.BaseSize(); DCHECK_GE(num_bytes_allocated_, map_size); size_t allocation_size = map_size; num_bytes_allocated_ -= allocation_size; --num_objects_allocated_; large_objects_.erase(it); return allocation_size; } size_t LargeObjectMapSpace::AllocationSize(mirror::Object* obj, size_t* usable_size) { MutexLock mu(Thread::Current(), lock_); auto it = large_objects_.find(obj); CHECK(it != large_objects_.end()) << "Attempted to get size of a large object which is not live"; size_t alloc_size = it->second.mem_map.BaseSize(); if (usable_size != nullptr) { *usable_size = alloc_size; } return alloc_size; } size_t LargeObjectSpace::FreeList(Thread* self, size_t num_ptrs, mirror::Object** ptrs) { size_t total = 0; for (size_t i = 0; i < num_ptrs; ++i) { if (kDebugSpaces) { CHECK(Contains(ptrs[i])); } total += Free(self, ptrs[i]); } return total; } void LargeObjectMapSpace::Walk(DlMallocSpace::WalkCallback callback, void* arg) { MutexLock mu(Thread::Current(), lock_); for (auto& pair : large_objects_) { MemMap* mem_map = &pair.second.mem_map; callback(mem_map->Begin(), mem_map->End(), mem_map->Size(), arg); callback(nullptr, nullptr, 0, arg); } } void LargeObjectMapSpace::ForEachMemMap(std::function func) const { MutexLock mu(Thread::Current(), lock_); for (auto& pair : large_objects_) { func(pair.second.mem_map); } } bool LargeObjectMapSpace::Contains(const mirror::Object* obj) const { Thread* self = Thread::Current(); if (lock_.IsExclusiveHeld(self)) { // We hold lock_ so do the check. return large_objects_.find(const_cast(obj)) != large_objects_.end(); } else { MutexLock mu(self, lock_); return large_objects_.find(const_cast(obj)) != large_objects_.end(); } } // Keeps track of allocation sizes + whether or not the previous allocation is free. // Used to coalesce free blocks and find the best fit block for an allocation for best fit object // allocation. Each allocation has an AllocationInfo which contains the size of the previous free // block preceding it. Implemented in such a way that we can also find the iterator for any // allocation info pointer. class AllocationInfo { public: AllocationInfo() : prev_free_(0), alloc_size_(0) { } // Return the number of pages that the allocation info covers. size_t AlignSize() const { return alloc_size_ & kFlagsMask; } // Returns the allocation size in bytes. size_t ByteSize() const { return AlignSize() * FreeListSpace::kAlignment; } // Updates the allocation size and whether or not it is free. void SetByteSize(size_t size, bool free) { DCHECK_EQ(size & ~kFlagsMask, 0u); DCHECK_ALIGNED(size, FreeListSpace::kAlignment); alloc_size_ = (size / FreeListSpace::kAlignment) | (free ? kFlagFree : 0u); } // Returns true if the block is free. bool IsFree() const { return (alloc_size_ & kFlagFree) != 0; } // Return true if the large object is a zygote object. bool IsZygoteObject() const { return (alloc_size_ & kFlagZygote) != 0; } // Change the object to be a zygote object. void SetZygoteObject() { alloc_size_ |= kFlagZygote; } // Return true if this is a zygote large object. // Finds and returns the next non free allocation info after ourself. AllocationInfo* GetNextInfo() { return this + AlignSize(); } const AllocationInfo* GetNextInfo() const { return this + AlignSize(); } // Returns the previous free allocation info by using the prev_free_ member to figure out // where it is. This is only used for coalescing so we only need to be able to do it if the // previous allocation info is free. AllocationInfo* GetPrevFreeInfo() { DCHECK_NE(prev_free_, 0U); return this - prev_free_; } // Returns the address of the object associated with this allocation info. mirror::Object* GetObjectAddress() { return reinterpret_cast(reinterpret_cast(this) + sizeof(*this)); } // Return how many kAlignment units there are before the free block. size_t GetPrevFree() const { return prev_free_; } // Returns how many free bytes there is before the block. size_t GetPrevFreeBytes() const { return GetPrevFree() * FreeListSpace::kAlignment; } // Update the size of the free block prior to the allocation. void SetPrevFreeBytes(size_t bytes) { DCHECK_ALIGNED(bytes, FreeListSpace::kAlignment); prev_free_ = bytes / FreeListSpace::kAlignment; } private: static constexpr uint32_t kFlagFree = 0x80000000; // If block is free. static constexpr uint32_t kFlagZygote = 0x40000000; // If the large object is a zygote object. static constexpr uint32_t kFlagsMask = ~(kFlagFree | kFlagZygote); // Combined flags for masking. // Contains the size of the previous free block with kAlignment as the unit. If 0 then the // allocation before us is not free. // These variables are undefined in the middle of allocations / free blocks. uint32_t prev_free_; // Allocation size of this object in kAlignment as the unit. uint32_t alloc_size_; }; size_t FreeListSpace::GetSlotIndexForAllocationInfo(const AllocationInfo* info) const { DCHECK_GE(info, allocation_info_); DCHECK_LT(info, reinterpret_cast(allocation_info_map_.End())); return info - allocation_info_; } AllocationInfo* FreeListSpace::GetAllocationInfoForAddress(uintptr_t address) { return &allocation_info_[GetSlotIndexForAddress(address)]; } const AllocationInfo* FreeListSpace::GetAllocationInfoForAddress(uintptr_t address) const { return &allocation_info_[GetSlotIndexForAddress(address)]; } inline bool FreeListSpace::SortByPrevFree::operator()(const AllocationInfo* a, const AllocationInfo* b) const { if (a->GetPrevFree() < b->GetPrevFree()) return true; if (a->GetPrevFree() > b->GetPrevFree()) return false; if (a->AlignSize() < b->AlignSize()) return true; if (a->AlignSize() > b->AlignSize()) return false; return reinterpret_cast(a) < reinterpret_cast(b); } FreeListSpace* FreeListSpace::Create(const std::string& name, size_t size) { CHECK_EQ(size % kAlignment, 0U); std::string error_msg; MemMap mem_map = MemMap::MapAnonymous(name.c_str(), size, PROT_READ | PROT_WRITE, /*low_4gb=*/ true, &error_msg); CHECK(mem_map.IsValid()) << "Failed to allocate large object space mem map: " << error_msg; return new FreeListSpace(name, std::move(mem_map), mem_map.Begin(), mem_map.End()); } FreeListSpace::FreeListSpace(const std::string& name, MemMap&& mem_map, uint8_t* begin, uint8_t* end) : LargeObjectSpace(name, begin, end, "free list space lock"), mem_map_(std::move(mem_map)) { const size_t space_capacity = end - begin; free_end_ = space_capacity; CHECK_ALIGNED(space_capacity, kAlignment); const size_t alloc_info_size = sizeof(AllocationInfo) * (space_capacity / kAlignment); std::string error_msg; allocation_info_map_ = MemMap::MapAnonymous("large object free list space allocation info map", alloc_info_size, PROT_READ | PROT_WRITE, /*low_4gb=*/ false, &error_msg); CHECK(allocation_info_map_.IsValid()) << "Failed to allocate allocation info map" << error_msg; allocation_info_ = reinterpret_cast(allocation_info_map_.Begin()); } FreeListSpace::~FreeListSpace() {} void FreeListSpace::Walk(DlMallocSpace::WalkCallback callback, void* arg) { MutexLock mu(Thread::Current(), lock_); const uintptr_t free_end_start = reinterpret_cast(end_) - free_end_; AllocationInfo* cur_info = &allocation_info_[0]; const AllocationInfo* end_info = GetAllocationInfoForAddress(free_end_start); while (cur_info < end_info) { if (!cur_info->IsFree()) { size_t alloc_size = cur_info->ByteSize(); uint8_t* byte_start = reinterpret_cast(GetAddressForAllocationInfo(cur_info)); uint8_t* byte_end = byte_start + alloc_size; callback(byte_start, byte_end, alloc_size, arg); callback(nullptr, nullptr, 0, arg); } cur_info = cur_info->GetNextInfo(); } CHECK_EQ(cur_info, end_info); } void FreeListSpace::ForEachMemMap(std::function func) const { MutexLock mu(Thread::Current(), lock_); func(allocation_info_map_); func(mem_map_); } void FreeListSpace::RemoveFreePrev(AllocationInfo* info) { CHECK_GT(info->GetPrevFree(), 0U); auto it = free_blocks_.lower_bound(info); CHECK(it != free_blocks_.end()); CHECK_EQ(*it, info); free_blocks_.erase(it); } size_t FreeListSpace::Free(Thread* self, mirror::Object* obj) { DCHECK(Contains(obj)) << reinterpret_cast(Begin()) << " " << obj << " " << reinterpret_cast(End()); DCHECK_ALIGNED(obj, kAlignment); AllocationInfo* info = GetAllocationInfoForAddress(reinterpret_cast(obj)); DCHECK(!info->IsFree()); const size_t allocation_size = info->ByteSize(); DCHECK_GT(allocation_size, 0U); DCHECK_ALIGNED(allocation_size, kAlignment); // madvise the pages without lock madvise(obj, allocation_size, MADV_DONTNEED); if (kIsDebugBuild) { // Can't disallow reads since we use them to find next chunks during coalescing. CheckedCall(mprotect, __FUNCTION__, obj, allocation_size, PROT_READ); } MutexLock mu(self, lock_); info->SetByteSize(allocation_size, true); // Mark as free. // Look at the next chunk. AllocationInfo* next_info = info->GetNextInfo(); // Calculate the start of the end free block. uintptr_t free_end_start = reinterpret_cast(end_) - free_end_; size_t prev_free_bytes = info->GetPrevFreeBytes(); size_t new_free_size = allocation_size; if (prev_free_bytes != 0) { // Coalesce with previous free chunk. new_free_size += prev_free_bytes; RemoveFreePrev(info); info = info->GetPrevFreeInfo(); // The previous allocation info must not be free since we are supposed to always coalesce. DCHECK_EQ(info->GetPrevFreeBytes(), 0U) << "Previous allocation was free"; } uintptr_t next_addr = GetAddressForAllocationInfo(next_info); if (next_addr >= free_end_start) { // Easy case, the next chunk is the end free region. CHECK_EQ(next_addr, free_end_start); free_end_ += new_free_size; } else { AllocationInfo* new_free_info; if (next_info->IsFree()) { AllocationInfo* next_next_info = next_info->GetNextInfo(); // Next next info can't be free since we always coalesce. DCHECK(!next_next_info->IsFree()); DCHECK_ALIGNED(next_next_info->ByteSize(), kAlignment); new_free_info = next_next_info; new_free_size += next_next_info->GetPrevFreeBytes(); RemoveFreePrev(next_next_info); } else { new_free_info = next_info; } new_free_info->SetPrevFreeBytes(new_free_size); free_blocks_.insert(new_free_info); info->SetByteSize(new_free_size, true); DCHECK_EQ(info->GetNextInfo(), new_free_info); } --num_objects_allocated_; DCHECK_LE(allocation_size, num_bytes_allocated_); num_bytes_allocated_ -= allocation_size; return allocation_size; } size_t FreeListSpace::AllocationSize(mirror::Object* obj, size_t* usable_size) { DCHECK(Contains(obj)); AllocationInfo* info = GetAllocationInfoForAddress(reinterpret_cast(obj)); DCHECK(!info->IsFree()); size_t alloc_size = info->ByteSize(); if (usable_size != nullptr) { *usable_size = alloc_size; } return alloc_size; } mirror::Object* FreeListSpace::Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated, size_t* usable_size, size_t* bytes_tl_bulk_allocated) { MutexLock mu(self, lock_); const size_t allocation_size = RoundUp(num_bytes, kAlignment); AllocationInfo temp_info; temp_info.SetPrevFreeBytes(allocation_size); temp_info.SetByteSize(0, false); AllocationInfo* new_info; // Find the smallest chunk at least num_bytes in size. auto it = free_blocks_.lower_bound(&temp_info); if (it != free_blocks_.end()) { AllocationInfo* info = *it; free_blocks_.erase(it); // Fit our object in the previous allocation info free space. new_info = info->GetPrevFreeInfo(); // Remove the newly allocated block from the info and update the prev_free_. info->SetPrevFreeBytes(info->GetPrevFreeBytes() - allocation_size); if (info->GetPrevFreeBytes() > 0) { AllocationInfo* new_free = info - info->GetPrevFree(); new_free->SetPrevFreeBytes(0); new_free->SetByteSize(info->GetPrevFreeBytes(), true); // If there is remaining space, insert back into the free set. free_blocks_.insert(info); } } else { // Try to steal some memory from the free space at the end of the space. if (LIKELY(free_end_ >= allocation_size)) { // Fit our object at the start of the end free block. new_info = GetAllocationInfoForAddress(reinterpret_cast(End()) - free_end_); free_end_ -= allocation_size; } else { return nullptr; } } DCHECK(bytes_allocated != nullptr); *bytes_allocated = allocation_size; if (usable_size != nullptr) { *usable_size = allocation_size; } DCHECK(bytes_tl_bulk_allocated != nullptr); *bytes_tl_bulk_allocated = allocation_size; // Need to do these inside of the lock. ++num_objects_allocated_; ++total_objects_allocated_; num_bytes_allocated_ += allocation_size; total_bytes_allocated_ += allocation_size; mirror::Object* obj = reinterpret_cast(GetAddressForAllocationInfo(new_info)); // We always put our object at the start of the free block, there cannot be another free block // before it. if (kIsDebugBuild) { CheckedCall(mprotect, __FUNCTION__, obj, allocation_size, PROT_READ | PROT_WRITE); } new_info->SetPrevFreeBytes(0); new_info->SetByteSize(allocation_size, false); return obj; } void FreeListSpace::Dump(std::ostream& os) const { MutexLock mu(Thread::Current(), lock_); os << GetName() << " -" << " begin: " << reinterpret_cast(Begin()) << " end: " << reinterpret_cast(End()) << "\n"; uintptr_t free_end_start = reinterpret_cast(end_) - free_end_; const AllocationInfo* cur_info = GetAllocationInfoForAddress(reinterpret_cast(Begin())); const AllocationInfo* end_info = GetAllocationInfoForAddress(free_end_start); while (cur_info < end_info) { size_t size = cur_info->ByteSize(); uintptr_t address = GetAddressForAllocationInfo(cur_info); if (cur_info->IsFree()) { os << "Free block at address: " << reinterpret_cast(address) << " of length " << size << " bytes\n"; } else { os << "Large object at address: " << reinterpret_cast(address) << " of length " << size << " bytes\n"; } cur_info = cur_info->GetNextInfo(); } if (free_end_) { os << "Free block at address: " << reinterpret_cast(free_end_start) << " of length " << free_end_ << " bytes\n"; } } bool FreeListSpace::IsZygoteLargeObject(Thread* self ATTRIBUTE_UNUSED, mirror::Object* obj) const { const AllocationInfo* info = GetAllocationInfoForAddress(reinterpret_cast(obj)); DCHECK(info != nullptr); return info->IsZygoteObject(); } void FreeListSpace::SetAllLargeObjectsAsZygoteObjects(Thread* self, bool set_mark_bit) { MutexLock mu(self, lock_); uintptr_t free_end_start = reinterpret_cast(end_) - free_end_; for (AllocationInfo* cur_info = GetAllocationInfoForAddress(reinterpret_cast(Begin())), *end_info = GetAllocationInfoForAddress(free_end_start); cur_info < end_info; cur_info = cur_info->GetNextInfo()) { if (!cur_info->IsFree()) { cur_info->SetZygoteObject(); if (set_mark_bit) { ObjPtr obj = reinterpret_cast(GetAddressForAllocationInfo(cur_info)); bool success = obj->AtomicSetMarkBit(0, 1); CHECK(success); } } } } void LargeObjectSpace::SweepCallback(size_t num_ptrs, mirror::Object** ptrs, void* arg) { SweepCallbackContext* context = static_cast(arg); space::LargeObjectSpace* space = context->space->AsLargeObjectSpace(); Thread* self = context->self; Locks::heap_bitmap_lock_->AssertExclusiveHeld(self); // If the bitmaps aren't swapped we need to clear the bits since the GC isn't going to re-swap // the bitmaps as an optimization. if (!context->swap_bitmaps) { accounting::LargeObjectBitmap* bitmap = space->GetLiveBitmap(); for (size_t i = 0; i < num_ptrs; ++i) { bitmap->Clear(ptrs[i]); } } context->freed.objects += num_ptrs; context->freed.bytes += space->FreeList(self, num_ptrs, ptrs); } collector::ObjectBytePair LargeObjectSpace::Sweep(bool swap_bitmaps) { if (Begin() >= End()) { return collector::ObjectBytePair(0, 0); } accounting::LargeObjectBitmap* live_bitmap = GetLiveBitmap(); accounting::LargeObjectBitmap* mark_bitmap = GetMarkBitmap(); if (swap_bitmaps) { std::swap(live_bitmap, mark_bitmap); } AllocSpace::SweepCallbackContext scc(swap_bitmaps, this); std::pair range = GetBeginEndAtomic(); accounting::LargeObjectBitmap::SweepWalk(*live_bitmap, *mark_bitmap, reinterpret_cast(range.first), reinterpret_cast(range.second), SweepCallback, &scc); return scc.freed; } void LargeObjectSpace::LogFragmentationAllocFailure(std::ostream& /*os*/, size_t /*failed_alloc_bytes*/) { UNIMPLEMENTED(FATAL); } std::pair LargeObjectMapSpace::GetBeginEndAtomic() const { MutexLock mu(Thread::Current(), lock_); return std::make_pair(Begin(), End()); } std::pair FreeListSpace::GetBeginEndAtomic() const { MutexLock mu(Thread::Current(), lock_); return std::make_pair(Begin(), End()); } } // namespace space } // namespace gc } // namespace art