149 lines
3.0 KiB
C++
149 lines
3.0 KiB
C++
//
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// detail/object_pool.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef BOOST_ASIO_DETAIL_OBJECT_POOL_HPP
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#define BOOST_ASIO_DETAIL_OBJECT_POOL_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include <boost/asio/detail/noncopyable.hpp>
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#include <boost/asio/detail/push_options.hpp>
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namespace boost {
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namespace asio {
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namespace detail {
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template <typename Object>
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class object_pool;
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class object_pool_access
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{
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public:
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template <typename Object>
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static Object* create()
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{
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return new Object;
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}
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template <typename Object>
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static void destroy(Object* o)
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{
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delete o;
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}
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template <typename Object>
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static Object*& next(Object* o)
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{
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return o->next_;
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}
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template <typename Object>
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static Object*& prev(Object* o)
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{
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return o->prev_;
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}
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};
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template <typename Object>
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class object_pool
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: private noncopyable
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{
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public:
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// Constructor.
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object_pool()
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: live_list_(0),
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free_list_(0)
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{
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}
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// Destructor destroys all objects.
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~object_pool()
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{
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destroy_list(live_list_);
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destroy_list(free_list_);
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}
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// Get the object at the start of the live list.
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Object* first()
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{
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return live_list_;
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}
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// Allocate a new object.
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Object* alloc()
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{
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Object* o = free_list_;
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if (o)
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free_list_ = object_pool_access::next(free_list_);
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else
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o = object_pool_access::create<Object>();
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object_pool_access::next(o) = live_list_;
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object_pool_access::prev(o) = 0;
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if (live_list_)
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object_pool_access::prev(live_list_) = o;
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live_list_ = o;
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return o;
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}
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// Free an object. Moves it to the free list. No destructors are run.
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void free(Object* o)
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{
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if (live_list_ == o)
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live_list_ = object_pool_access::next(o);
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if (object_pool_access::prev(o))
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{
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object_pool_access::next(object_pool_access::prev(o))
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= object_pool_access::next(o);
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}
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if (object_pool_access::next(o))
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{
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object_pool_access::prev(object_pool_access::next(o))
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= object_pool_access::prev(o);
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}
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object_pool_access::next(o) = free_list_;
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object_pool_access::prev(o) = 0;
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free_list_ = o;
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}
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private:
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// Helper function to destroy all elements in a list.
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void destroy_list(Object* list)
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{
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while (list)
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{
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Object* o = list;
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list = object_pool_access::next(o);
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object_pool_access::destroy(o);
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}
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}
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// The list of live objects.
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Object* live_list_;
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// The free list.
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Object* free_list_;
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};
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} // namespace detail
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} // namespace asio
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} // namespace boost
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#include <boost/asio/detail/pop_options.hpp>
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#endif // BOOST_ASIO_DETAIL_OBJECT_POOL_HPP
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