forked from boostorg/beast
196d9c60fa
fix #440 WARNING multi_buffer constructor now takes a maximum size instead of the "allocation size". This is a breaking change. The allocation size feature is removed. To update calling code, remove the allocation size parameter from call sites. * multi_buffer now uses a geometric growth algorithm for better performance.
306 lines
8.5 KiB
C++
306 lines
8.5 KiB
C++
//
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// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail 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 BEAST_MULTI_BUFFER_HPP
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#define BEAST_MULTI_BUFFER_HPP
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#include <beast/config.hpp>
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#include <beast/core/detail/empty_base_optimization.hpp>
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#include <boost/asio/buffer.hpp>
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#include <boost/intrusive/list.hpp>
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#include <iterator>
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#include <limits>
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#include <memory>
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#include <type_traits>
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namespace beast {
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/** A @b DynamicBuffer that uses multiple buffers internally.
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The implementation uses a sequence of one or more character arrays
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of varying sizes. Additional character array objects are appended to
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the sequence to accommodate changes in the size of the character
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sequence.
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@note Meets the requirements of @b DynamicBuffer.
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@tparam Allocator The allocator to use for managing memory.
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*/
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template<class Allocator>
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class basic_multi_buffer
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#if ! BEAST_DOXYGEN
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: private detail::empty_base_optimization<
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typename std::allocator_traits<Allocator>::
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template rebind_alloc<char>>
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#endif
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{
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public:
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#if BEAST_DOXYGEN
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/// The type of allocator used.
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using allocator_type = Allocator;
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#else
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using allocator_type = typename
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std::allocator_traits<Allocator>::
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template rebind_alloc<char>;
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#endif
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private:
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// Storage for the list of buffers representing the input
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// and output sequences. The allocation for each element
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// contains `element` followed by raw storage bytes.
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class element;
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using alloc_traits = std::allocator_traits<allocator_type>;
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using list_type = typename boost::intrusive::make_list<element,
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boost::intrusive::constant_time_size<true>>::type;
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using iterator = typename list_type::iterator;
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using const_iterator = typename list_type::const_iterator;
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using size_type = typename std::allocator_traits<Allocator>::size_type;
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using const_buffer = boost::asio::const_buffer;
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using mutable_buffer = boost::asio::mutable_buffer;
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static_assert(std::is_base_of<std::bidirectional_iterator_tag,
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typename std::iterator_traits<iterator>::iterator_category>::value,
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"BidirectionalIterator requirements not met");
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static_assert(std::is_base_of<std::bidirectional_iterator_tag,
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typename std::iterator_traits<const_iterator>::iterator_category>::value,
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"BidirectionalIterator requirements not met");
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std::size_t max_ =
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(std::numeric_limits<std::size_t>::max)();
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list_type list_; // list of allocated buffers
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iterator out_; // element that contains out_pos_
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size_type in_size_ = 0; // size of the input sequence
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size_type in_pos_ = 0; // input offset in list_.front()
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size_type out_pos_ = 0; // output offset in *out_
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size_type out_end_ = 0; // output end offset in list_.back()
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public:
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#if BEAST_DOXYGEN
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/// The type used to represent the input sequence as a list of buffers.
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using const_buffers_type = implementation_defined;
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/// The type used to represent the output sequence as a list of buffers.
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using mutable_buffers_type = implementation_defined;
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#else
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class const_buffers_type;
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class mutable_buffers_type;
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#endif
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/// Destructor.
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~basic_multi_buffer();
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/// Default constructor.
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basic_multi_buffer();
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/** Move constructor.
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The new object will have the input sequence of
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the other stream buffer, and an empty output sequence.
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@note After the move, the moved-from object will have
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an empty input and output sequence, with no internal
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buffers allocated.
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*/
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basic_multi_buffer(basic_multi_buffer&&);
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/** Move constructor.
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The new object will have the input sequence of
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the other stream buffer, and an empty output sequence.
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@note After the move, the moved-from object will have
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an empty input and output sequence, with no internal
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buffers allocated.
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@param alloc The allocator to associate with the
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stream buffer.
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*/
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basic_multi_buffer(basic_multi_buffer&&,
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allocator_type const& alloc);
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/** Copy constructor.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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*/
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basic_multi_buffer(basic_multi_buffer const&);
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/** Copy constructor.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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@param alloc The allocator to associate with the
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stream buffer.
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*/
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basic_multi_buffer(basic_multi_buffer const&,
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allocator_type const& alloc);
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/** Copy constructor.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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*/
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template<class OtherAlloc>
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basic_multi_buffer(basic_multi_buffer<OtherAlloc> const&);
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/** Copy constructor.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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@param alloc The allocator to associate with the
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stream buffer.
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*/
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template<class OtherAlloc>
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basic_multi_buffer(basic_multi_buffer<OtherAlloc> const&,
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allocator_type const& alloc);
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/** Constructor.
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@param limit The maximum allowed sum of the input and
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output sequence sizes.
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*/
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explicit
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basic_multi_buffer(std::size_t limit);
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/** Constructor.
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@param limit The maximum allowed sum of the input and
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output sequence sizes.
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@param alloc The allocator to use.
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*/
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basic_multi_buffer(
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std::size_t limit, Allocator const& alloc);
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/** Move assignment.
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This object will have the input sequence of
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the other stream buffer, and an empty output sequence.
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@note After the move, the moved-from object will have
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an empty input and output sequence, with no internal
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buffers allocated.
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*/
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basic_multi_buffer&
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operator=(basic_multi_buffer&&);
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/** Copy assignment.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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*/
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basic_multi_buffer& operator=(basic_multi_buffer const&);
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/** Copy assignment.
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This object will have a copy of the other stream
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buffer's input sequence, and an empty output sequence.
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*/
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template<class OtherAlloc>
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basic_multi_buffer& operator=(basic_multi_buffer<OtherAlloc> const&);
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/// Returns a copy of the associated allocator.
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allocator_type
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get_allocator() const
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{
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return this->member();
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}
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/// Returns the size of the input sequence.
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size_type
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size() const
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{
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return in_size_;
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}
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/// Returns the permitted maximum sum of the sizes of the input and output sequence.
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size_type
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max_size() const
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{
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return max_;
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}
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/// Returns the maximum sum of the sizes of the input sequence and output sequence the buffer can hold without requiring reallocation.
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std::size_t
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capacity() const;
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/** Get a list of buffers that represents the input sequence.
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@note These buffers remain valid across subsequent calls to `prepare`.
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*/
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const_buffers_type
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data() const;
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/** Get a list of buffers that represents the output sequence, with the given size.
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@note Buffers representing the input sequence acquired prior to
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this call remain valid.
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*/
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mutable_buffers_type
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prepare(size_type n);
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/** Move bytes from the output sequence to the input sequence.
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@note Buffers representing the input sequence acquired prior to
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this call remain valid.
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*/
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void
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commit(size_type n);
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/// Remove bytes from the input sequence.
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void
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consume(size_type n);
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private:
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void
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clear();
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void
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move_assign(basic_multi_buffer& other, std::false_type);
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void
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move_assign(basic_multi_buffer& other, std::true_type);
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void
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copy_assign(basic_multi_buffer const& other, std::false_type);
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void
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copy_assign(basic_multi_buffer const& other, std::true_type);
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void
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delete_list();
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void
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debug_check() const;
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};
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#if 0
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/// Helper for boost::asio::read_until
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template<class Allocator>
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std::size_t
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read_size_helper(
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basic_multi_buffer<Allocator> const& buffer,
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std::size_t max_size);
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#endif
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/// A typical multi buffer
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using multi_buffer = basic_multi_buffer<std::allocator<char>>;
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} // beast
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#include <beast/core/impl/multi_buffer.ipp>
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#endif
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