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/*
* Copyright 2012 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 = alloc.allocate(allocSize);
assert(isAligned(mem));
return std::make_pair(new (mem) Block(), allocSize - sizeof(Block));
}
template <class Alloc>
void Arena<Alloc>::Block::deallocate(Alloc& alloc) {
this->~Block();
alloc.deallocate(this);
}
template <class Alloc>
void* Arena<Alloc>::allocateSlow(size_t size) {
std::pair<Block*, size_t> p;
char* start;
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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