84 lines
2.7 KiB
C++
84 lines
2.7 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef FOLLY_ARENA_H_
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#error This file may only be included from Arena.h
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#endif
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// Implementation of Arena.h functions
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#include <folly/lang/SafeAssert.h>
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namespace folly {
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template <class Alloc>
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void* Arena<Alloc>::allocateSlow(size_t size) {
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char* start;
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size_t allocSize;
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if (!checked_add(&allocSize, std::max(size, minBlockSize()), sizeof(Block))) {
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throw_exception<std::bad_alloc>();
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}
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if (sizeLimit_ != kNoSizeLimit &&
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allocSize > sizeLimit_ - totalAllocatedSize_) {
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throw_exception<std::bad_alloc>();
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}
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if (size > minBlockSize()) {
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// Allocate a large block for this chunk only; don't change ptr_ and end_,
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// let them point into a normal block (or none, if they're null)
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allocSize = sizeof(LargeBlock) + size;
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void* mem = AllocTraits::allocate(alloc(), allocSize);
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auto blk = new (mem) LargeBlock(allocSize);
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start = blk->start();
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largeBlocks_.push_back(*blk);
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} else {
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// Allocate a normal sized block and carve out size bytes from it
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// Will allocate more than size bytes if convenient
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// (via ArenaAllocatorTraits::goodSize()) as we'll try to pack small
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// allocations in this block.
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allocSize = blockGoodAllocSize();
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void* mem = AllocTraits::allocate(alloc(), allocSize);
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auto blk = new (mem) Block();
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start = blk->start();
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blocks_.push_back(*blk);
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currentBlock_ = blocks_.last();
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ptr_ = start + size;
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end_ = start + allocSize - sizeof(Block);
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assert(ptr_ <= end_);
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}
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totalAllocatedSize_ += allocSize;
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return start;
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}
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template <class Alloc>
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void Arena<Alloc>::merge(Arena<Alloc>&& other) {
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FOLLY_SAFE_CHECK(
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blockGoodAllocSize() == other.blockGoodAllocSize(),
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"cannot merge arenas of different minBlockSize");
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blocks_.splice_after(blocks_.before_begin(), other.blocks_);
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other.blocks_.clear();
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largeBlocks_.splice_after(largeBlocks_.before_begin(), other.largeBlocks_);
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other.largeBlocks_.clear();
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other.ptr_ = other.end_ = nullptr;
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totalAllocatedSize_ += other.totalAllocatedSize_;
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other.totalAllocatedSize_ = 0;
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bytesUsed_ += other.bytesUsed_;
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other.bytesUsed_ = 0;
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}
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} // namespace folly
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