94 lines
2.8 KiB
C++
94 lines
2.8 KiB
C++
/*
|
|
* 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
|