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- /*
- * Copyright 2012-present Facebook, Inc.
- *
- * 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.
- */
- #ifndef FOLLY_ARENA_H_
- #error This file may only be included from Arena.h
- #endif
- // Implementation of Arena.h functions
- namespace folly {
- template <class Alloc>
- std::pair<typename Arena<Alloc>::Block*, size_t>
- Arena<Alloc>::Block::allocate(Alloc& alloc, size_t size, bool allowSlack) {
- size_t allocSize = sizeof(Block) + size;
- if (allowSlack) {
- allocSize = ArenaAllocatorTraits<Alloc>::goodSize(alloc, allocSize);
- }
- void* mem = std::allocator_traits<Alloc>::allocate(alloc, allocSize);
- return std::make_pair(new (mem) Block(), allocSize - sizeof(Block));
- }
- template <class Alloc>
- void Arena<Alloc>::Block::deallocate(Alloc& alloc) {
- this->~Block();
- std::allocator_traits<Alloc>::deallocate(alloc, this, 1);
- }
- template <class Alloc>
- void* Arena<Alloc>::allocateSlow(size_t size) {
- std::pair<Block*, size_t> p;
- char* start;
- size_t allocSize = std::max(size, minBlockSize()) + sizeof(Block);
- if (sizeLimit_ != kNoSizeLimit &&
- allocSize > sizeLimit_ - totalAllocatedSize_) {
- throw_exception(std::bad_alloc());
- }
- if (size > minBlockSize()) {
- // Allocate a large block for this chunk only, put it at the back of the
- // list so it doesn't get used for small allocations; don't change ptr_
- // and end_, let them point into a normal block (or none, if they're
- // null)
- p = Block::allocate(alloc(), size, false);
- start = p.first->start();
- blocks_.push_back(*p.first);
- } else {
- // Allocate a normal sized block and carve out size bytes from it
- p = Block::allocate(alloc(), minBlockSize(), true);
- start = p.first->start();
- blocks_.push_front(*p.first);
- ptr_ = start + size;
- end_ = start + p.second;
- }
- assert(p.second >= size);
- totalAllocatedSize_ += p.second + sizeof(Block);
- return start;
- }
- template <class Alloc>
- void Arena<Alloc>::merge(Arena<Alloc>&& other) {
- blocks_.splice_after(blocks_.before_begin(), other.blocks_);
- other.blocks_.clear();
- other.ptr_ = other.end_ = nullptr;
- totalAllocatedSize_ += other.totalAllocatedSize_;
- other.totalAllocatedSize_ = 0;
- }
- template <class Alloc>
- Arena<Alloc>::~Arena() {
- auto disposer = [this](Block* b) { b->deallocate(this->alloc()); };
- while (!blocks_.empty()) {
- blocks_.pop_front_and_dispose(disposer);
- }
- }
- } // namespace folly
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