7dbd17a5aa
Former-commit-id:133dc97f67[formerlya02aeb236c] [formerly9f19e3f712] [formerly133dc97f67[formerlya02aeb236c] [formerly9f19e3f712] [formerly06a8b51d6d[formerly9f19e3f712[formerly 64fa9254b946eae7e61bbc3f513b7c3696c4f54f]]]] Former-commit-id:06a8b51d6dFormer-commit-id:9bb8decbcf[formerly8e80217e59] [formerly377dcd10b9[formerly3360eb6c5f]] Former-commit-id:377dcd10b9Former-commit-id:e2ecdcfe33
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
#ifndef QPID_INLINEALLOCATOR_H
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#define QPID_INLINEALLOCATOR_H
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/*
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*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. 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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*
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*/
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#include <memory>
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#include <assert.h>
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#include <boost/type_traits/type_with_alignment.hpp>
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#include <boost/type_traits/alignment_of.hpp>
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namespace qpid {
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template <typename RequestedType, typename InlineType, typename BaseAllocator, size_t Max>
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struct InlineRebind;
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/**
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* An allocator that has inline storage for up to Max objects
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* of type BaseAllocator::value_type.
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*/
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template <class BaseAllocator, size_t Max>
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class InlineAllocator : public BaseAllocator {
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public:
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typedef typename BaseAllocator::pointer pointer;
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typedef typename BaseAllocator::size_type size_type;
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typedef typename BaseAllocator::value_type value_type;
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InlineAllocator() : allocated(false) {}
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InlineAllocator(const InlineAllocator& x) : BaseAllocator(x), allocated(false) {}
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pointer allocate(size_type n) {
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if (n <= Max && !allocated) {
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allocated=true;
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return reinterpret_cast<value_type*>(address());
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}
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else
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return BaseAllocator::allocate(n, 0);
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}
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void deallocate(pointer p, size_type n) {
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if (p == address()) {
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assert(allocated);
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allocated=false;
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}
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else
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BaseAllocator::deallocate(p, n);
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}
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template<typename T1>
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struct rebind {
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typedef typename InlineRebind<T1, value_type, BaseAllocator, Max>::other other;
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};
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private:
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// POD object with alignment and size to hold Max value_types.
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static const size_t ALIGNMENT=boost::alignment_of<value_type>::value;
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typedef typename boost::type_with_alignment<ALIGNMENT>::type Aligner;
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union Store {
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Aligner aligner_;
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char sizer_[sizeof(value_type)*Max];
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} store;
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value_type* address() { return reinterpret_cast<value_type*>(&store); }
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bool allocated;
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};
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// Rebind: if RequestedType == InlineType, use the InlineAllocator,
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// otherwise, use the BaseAllocator without any inlining.
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template <typename RequestedType, typename InlineType, typename BaseAllocator, size_t Max>
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struct InlineRebind {
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typedef typename BaseAllocator::template rebind<RequestedType>::other other;
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};
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template <typename T, typename BaseAllocator, size_t Max>
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struct InlineRebind<T, T, BaseAllocator, Max> {
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typedef typename qpid::InlineAllocator<BaseAllocator, Max> other;
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};
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} // namespace qpid
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#endif /*!QPID_INLINEALLOCATOR_H*/
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