722 lines
21 KiB
C++
722 lines
21 KiB
C++
// lock-free single-producer/single-consumer ringbuffer
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// this algorithm is implemented in various projects (linux kernel)
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//
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// Copyright (C) 2009, 2011 Tim Blechmann
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED
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#define BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED
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#include <algorithm>
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#include <boost/array.hpp>
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#include <boost/assert.hpp>
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#ifdef BOOST_NO_CXX11_DELETED_FUNCTIONS
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#include <boost/noncopyable.hpp>
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#endif
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#include <boost/static_assert.hpp>
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#include <boost/lockfree/detail/atomic.hpp>
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#include <boost/lockfree/detail/branch_hints.hpp>
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#include <boost/lockfree/detail/parameter.hpp>
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#include <boost/lockfree/detail/prefix.hpp>
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namespace boost {
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namespace lockfree {
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namespace detail {
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typedef parameter::parameters<boost::parameter::optional<tag::capacity>,
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boost::parameter::optional<tag::allocator>
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> ringbuffer_signature;
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template <typename T>
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class ringbuffer_base
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#ifdef BOOST_NO_CXX11_DELETED_FUNCTIONS
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: boost::noncopyable
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#endif
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{
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#ifndef BOOST_DOXYGEN_INVOKED
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typedef std::size_t size_t;
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static const int padding_size = BOOST_LOCKFREE_CACHELINE_BYTES - sizeof(size_t);
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atomic<size_t> write_index_;
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char padding1[padding_size]; /* force read_index and write_index to different cache lines */
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atomic<size_t> read_index_;
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#ifndef BOOST_NO_CXX11_DELETED_FUNCTIONS
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ringbuffer_base(ringbuffer_base const &) = delete;
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ringbuffer_base(ringbuffer_base &&) = delete;
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const ringbuffer_base& operator=( const ringbuffer_base& ) = delete;
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#endif
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protected:
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ringbuffer_base(void):
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write_index_(0), read_index_(0)
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{}
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static size_t next_index(size_t arg, size_t max_size)
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{
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size_t ret = arg + 1;
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while (unlikely(ret >= max_size))
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ret -= max_size;
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return ret;
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}
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static size_t read_available(size_t write_index, size_t read_index, size_t max_size)
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{
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if (write_index >= read_index)
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return write_index - read_index;
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size_t ret = write_index + max_size - read_index;
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return ret;
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}
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static size_t write_available(size_t write_index, size_t read_index, size_t max_size)
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{
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size_t ret = read_index - write_index - 1;
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if (write_index >= read_index)
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ret += max_size;
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return ret;
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}
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bool push(T const & t, T * buffer, size_t max_size)
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{
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size_t write_index = write_index_.load(memory_order_relaxed); // only written from push thread
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size_t next = next_index(write_index, max_size);
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if (next == read_index_.load(memory_order_acquire))
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return false; /* ringbuffer is full */
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buffer[write_index] = t;
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write_index_.store(next, memory_order_release);
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return true;
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}
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size_t push(const T * input_buffer, size_t input_count, T * internal_buffer, size_t max_size)
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{
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size_t write_index = write_index_.load(memory_order_relaxed); // only written from push thread
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const size_t read_index = read_index_.load(memory_order_acquire);
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const size_t avail = write_available(write_index, read_index, max_size);
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if (avail == 0)
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return 0;
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input_count = (std::min)(input_count, avail);
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size_t new_write_index = write_index + input_count;
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if (write_index + input_count > max_size) {
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/* copy data in two sections */
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size_t count0 = max_size - write_index;
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std::copy(input_buffer, input_buffer + count0, internal_buffer + write_index);
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std::copy(input_buffer + count0, input_buffer + input_count, internal_buffer);
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new_write_index -= max_size;
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} else {
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std::copy(input_buffer, input_buffer + input_count, internal_buffer + write_index);
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if (new_write_index == max_size)
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new_write_index = 0;
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}
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write_index_.store(new_write_index, memory_order_release);
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return input_count;
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}
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template <typename ConstIterator>
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ConstIterator push(ConstIterator begin, ConstIterator end, T * internal_buffer, size_t max_size)
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{
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// FIXME: avoid std::distance and std::advance
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size_t write_index = write_index_.load(memory_order_relaxed); // only written from push thread
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const size_t read_index = read_index_.load(memory_order_acquire);
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const size_t avail = write_available(write_index, read_index, max_size);
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if (avail == 0)
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return begin;
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size_t input_count = std::distance(begin, end);
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input_count = (std::min)(input_count, avail);
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size_t new_write_index = write_index + input_count;
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ConstIterator last = begin;
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std::advance(last, input_count);
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if (write_index + input_count > max_size) {
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/* copy data in two sections */
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size_t count0 = max_size - write_index;
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ConstIterator midpoint = begin;
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std::advance(midpoint, count0);
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std::copy(begin, midpoint, internal_buffer + write_index);
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std::copy(midpoint, last, internal_buffer);
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new_write_index -= max_size;
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} else {
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std::copy(begin, last, internal_buffer + write_index);
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if (new_write_index == max_size)
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new_write_index = 0;
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}
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write_index_.store(new_write_index, memory_order_release);
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return last;
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}
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bool pop (T & ret, T * buffer, size_t max_size)
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{
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size_t write_index = write_index_.load(memory_order_acquire);
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size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
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if (empty(write_index, read_index))
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return false;
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ret = buffer[read_index];
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size_t next = next_index(read_index, max_size);
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read_index_.store(next, memory_order_release);
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return true;
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}
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size_t pop (T * output_buffer, size_t output_count, const T * internal_buffer, size_t max_size)
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{
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const size_t write_index = write_index_.load(memory_order_acquire);
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size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
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const size_t avail = read_available(write_index, read_index, max_size);
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if (avail == 0)
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return 0;
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output_count = (std::min)(output_count, avail);
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size_t new_read_index = read_index + output_count;
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if (read_index + output_count > max_size) {
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/* copy data in two sections */
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size_t count0 = max_size - read_index;
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size_t count1 = output_count - count0;
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std::copy(internal_buffer + read_index, internal_buffer + max_size, output_buffer);
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std::copy(internal_buffer, internal_buffer + count1, output_buffer + count0);
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new_read_index -= max_size;
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} else {
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std::copy(internal_buffer + read_index, internal_buffer + read_index + output_count, output_buffer);
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if (new_read_index == max_size)
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new_read_index = 0;
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}
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read_index_.store(new_read_index, memory_order_release);
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return output_count;
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}
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template <typename OutputIterator>
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size_t pop (OutputIterator it, const T * internal_buffer, size_t max_size)
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{
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const size_t write_index = write_index_.load(memory_order_acquire);
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size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
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const size_t avail = read_available(write_index, read_index, max_size);
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if (avail == 0)
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return 0;
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size_t new_read_index = read_index + avail;
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if (read_index + avail > max_size) {
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/* copy data in two sections */
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size_t count0 = max_size - read_index;
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size_t count1 = avail - count0;
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it = std::copy(internal_buffer + read_index, internal_buffer + max_size, it);
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std::copy(internal_buffer, internal_buffer + count1, it);
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new_read_index -= max_size;
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} else {
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std::copy(internal_buffer + read_index, internal_buffer + read_index + avail, it);
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if (new_read_index == max_size)
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new_read_index = 0;
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}
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read_index_.store(new_read_index, memory_order_release);
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return avail;
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}
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#endif
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public:
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/** reset the ringbuffer
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*
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* \note Not thread-safe
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* */
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void reset(void)
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{
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write_index_.store(0, memory_order_relaxed);
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read_index_.store(0, memory_order_release);
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}
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/** Check if the ringbuffer is empty
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*
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* \return true, if the ringbuffer is empty, false otherwise
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* \note Due to the concurrent nature of the ringbuffer the result may be inaccurate.
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* */
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bool empty(void)
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{
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return empty(write_index_.load(memory_order_relaxed), read_index_.load(memory_order_relaxed));
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}
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/**
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* \return true, if implementation is lock-free.
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*
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* */
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bool is_lock_free(void) const
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{
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return write_index_.is_lock_free() && read_index_.is_lock_free();
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}
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private:
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bool empty(size_t write_index, size_t read_index)
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{
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return write_index == read_index;
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}
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};
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template <typename T, std::size_t MaxSize>
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class compile_time_sized_ringbuffer:
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public ringbuffer_base<T>
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{
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typedef std::size_t size_t;
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static const std::size_t max_size = MaxSize + 1;
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boost::array<T, max_size> array_;
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public:
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bool push(T const & t)
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{
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return ringbuffer_base<T>::push(t, array_.c_array(), max_size);
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}
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bool pop(T & ret)
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{
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return ringbuffer_base<T>::pop(ret, array_.c_array(), max_size);
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}
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size_t push(T const * t, size_t size)
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{
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return ringbuffer_base<T>::push(t, size, array_.c_array(), max_size);
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}
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template <size_t size>
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size_t push(T const (&t)[size])
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{
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return push(t, size);
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}
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template <typename ConstIterator>
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ConstIterator push(ConstIterator begin, ConstIterator end)
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{
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return ringbuffer_base<T>::push(begin, end, array_.c_array(), max_size);
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}
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size_t pop(T * ret, size_t size)
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{
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return ringbuffer_base<T>::pop(ret, size, array_.c_array(), max_size);
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}
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template <size_t size>
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size_t pop(T (&ret)[size])
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{
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return pop(ret, size);
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}
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template <typename OutputIterator>
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size_t pop(OutputIterator it)
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{
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return ringbuffer_base<T>::pop(it, array_.c_array(), max_size);
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}
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};
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template <typename T, typename Alloc>
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class runtime_sized_ringbuffer:
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public ringbuffer_base<T>,
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private Alloc
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{
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typedef std::size_t size_t;
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size_t max_elements_;
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typedef typename Alloc::pointer pointer;
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pointer array_;
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public:
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explicit runtime_sized_ringbuffer(size_t max_elements):
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max_elements_(max_elements + 1)
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{
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// TODO: we don't necessarily need to construct all elements
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array_ = Alloc::allocate(max_elements_);
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for (size_t i = 0; i != max_elements_; ++i)
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Alloc::construct(array_ + i, T());
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}
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template <typename U>
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runtime_sized_ringbuffer(typename Alloc::template rebind<U>::other const & alloc, size_t max_elements):
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Alloc(alloc), max_elements_(max_elements + 1)
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{
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// TODO: we don't necessarily need to construct all elements
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array_ = Alloc::allocate(max_elements_);
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for (size_t i = 0; i != max_elements_; ++i)
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Alloc::construct(array_ + i, T());
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}
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runtime_sized_ringbuffer(Alloc const & alloc, size_t max_elements):
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Alloc(alloc), max_elements_(max_elements + 1)
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{
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// TODO: we don't necessarily need to construct all elements
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array_ = Alloc::allocate(max_elements_);
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for (size_t i = 0; i != max_elements_; ++i)
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Alloc::construct(array_ + i, T());
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}
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~runtime_sized_ringbuffer(void)
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{
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for (size_t i = 0; i != max_elements_; ++i)
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Alloc::destroy(array_ + i);
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Alloc::deallocate(array_, max_elements_);
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}
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bool push(T const & t)
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{
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return ringbuffer_base<T>::push(t, &*array_, max_elements_);
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}
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bool pop(T & ret)
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{
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return ringbuffer_base<T>::pop(ret, &*array_, max_elements_);
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}
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size_t push(T const * t, size_t size)
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{
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return ringbuffer_base<T>::push(t, size, &*array_, max_elements_);
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}
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template <size_t size>
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size_t push(T const (&t)[size])
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{
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return push(t, size);
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}
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template <typename ConstIterator>
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ConstIterator push(ConstIterator begin, ConstIterator end)
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{
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return ringbuffer_base<T>::push(begin, end, array_, max_elements_);
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}
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size_t pop(T * ret, size_t size)
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{
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return ringbuffer_base<T>::pop(ret, size, array_, max_elements_);
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}
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template <size_t size>
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size_t pop(T (&ret)[size])
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{
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return pop(ret, size);
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}
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template <typename OutputIterator>
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size_t pop(OutputIterator it)
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{
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return ringbuffer_base<T>::pop(it, array_, max_elements_);
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}
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};
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template <typename T, typename A0, typename A1>
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struct make_ringbuffer
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{
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typedef typename ringbuffer_signature::bind<A0, A1>::type bound_args;
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typedef extract_capacity<bound_args> extract_capacity_t;
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static const bool runtime_sized = !extract_capacity_t::has_capacity;
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static const size_t capacity = extract_capacity_t::capacity;
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typedef extract_allocator<bound_args, T> extract_allocator_t;
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typedef typename extract_allocator_t::type allocator;
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// allocator argument is only sane, for run-time sized ringbuffers
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BOOST_STATIC_ASSERT((mpl::if_<mpl::bool_<!runtime_sized>,
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mpl::bool_<!extract_allocator_t::has_allocator>,
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mpl::true_
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>::type::value));
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typedef typename mpl::if_c<runtime_sized,
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runtime_sized_ringbuffer<T, allocator>,
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compile_time_sized_ringbuffer<T, capacity>
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>::type ringbuffer_type;
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};
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} /* namespace detail */
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/** The spsc_queue class provides a single-writer/single-reader fifo queue, pushing and popping is wait-free.
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*
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* \b Policies:
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* - \c boost::lockfree::capacity<>, optional <br>
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* If this template argument is passed to the options, the size of the ringbuffer is set at compile-time.
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*
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* - \c boost::lockfree::allocator<>, defaults to \c boost::lockfree::allocator<std::allocator<T>> <br>
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* Specifies the allocator that is used to allocate the ringbuffer. This option is only valid, if the ringbuffer is configured
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* to be sized at run-time
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*
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* \b Requirements:
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* - T must have a default constructor
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* - T must be copyable
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* */
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#ifndef BOOST_DOXYGEN_INVOKED
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template <typename T,
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class A0 = boost::parameter::void_,
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class A1 = boost::parameter::void_>
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#else
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template <typename T, ...Options>
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#endif
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class spsc_queue:
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public detail::make_ringbuffer<T, A0, A1>::ringbuffer_type
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{
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private:
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#ifndef BOOST_DOXYGEN_INVOKED
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typedef typename detail::make_ringbuffer<T, A0, A1>::ringbuffer_type base_type;
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static const bool runtime_sized = detail::make_ringbuffer<T, A0, A1>::runtime_sized;
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typedef typename detail::make_ringbuffer<T, A0, A1>::allocator allocator_arg;
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struct implementation_defined
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{
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typedef allocator_arg allocator;
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typedef std::size_t size_type;
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};
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#endif
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public:
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typedef T value_type;
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typedef typename implementation_defined::allocator allocator;
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typedef typename implementation_defined::size_type size_type;
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/** Constructs a spsc_queue
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*
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* \pre spsc_queue must be configured to be sized at compile-time
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*/
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// @{
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spsc_queue(void)
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{
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BOOST_ASSERT(!runtime_sized);
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}
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template <typename U>
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explicit spsc_queue(typename allocator::template rebind<U>::other const & alloc)
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{
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// just for API compatibility: we don't actually need an allocator
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BOOST_STATIC_ASSERT(!runtime_sized);
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}
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explicit spsc_queue(allocator const & alloc)
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{
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// just for API compatibility: we don't actually need an allocator
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BOOST_ASSERT(!runtime_sized);
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}
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|
// @}
|
|
|
|
|
|
/** Constructs a spsc_queue for element_count elements
|
|
*
|
|
* \pre spsc_queue must be configured to be sized at run-time
|
|
*/
|
|
// @{
|
|
explicit spsc_queue(size_type element_count):
|
|
base_type(element_count)
|
|
{
|
|
BOOST_ASSERT(runtime_sized);
|
|
}
|
|
|
|
template <typename U>
|
|
spsc_queue(size_type element_count, typename allocator::template rebind<U>::other const & alloc):
|
|
base_type(alloc, element_count)
|
|
{
|
|
BOOST_STATIC_ASSERT(runtime_sized);
|
|
}
|
|
|
|
spsc_queue(size_type element_count, allocator_arg const & alloc):
|
|
base_type(alloc, element_count)
|
|
{
|
|
BOOST_ASSERT(runtime_sized);
|
|
}
|
|
// @}
|
|
|
|
/** Pushes object t to the ringbuffer.
|
|
*
|
|
* \pre only one thread is allowed to push data to the spsc_queue
|
|
* \post object will be pushed to the spsc_queue, unless it is full.
|
|
* \return true, if the push operation is successful.
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
* */
|
|
bool push(T const & t)
|
|
{
|
|
return base_type::push(t);
|
|
}
|
|
|
|
/** Pops one object from ringbuffer.
|
|
*
|
|
* \pre only one thread is allowed to pop data to the spsc_queue
|
|
* \post if ringbuffer is not empty, object will be copied to ret.
|
|
* \return true, if the pop operation is successful, false if ringbuffer was empty.
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
*/
|
|
bool pop(T & ret)
|
|
{
|
|
return base_type::pop(ret);
|
|
}
|
|
|
|
/** Pushes as many objects from the array t as there is space.
|
|
*
|
|
* \pre only one thread is allowed to push data to the spsc_queue
|
|
* \return number of pushed items
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
*/
|
|
size_type push(T const * t, size_type size)
|
|
{
|
|
return base_type::push(t, size);
|
|
}
|
|
|
|
/** Pushes as many objects from the array t as there is space available.
|
|
*
|
|
* \pre only one thread is allowed to push data to the spsc_queue
|
|
* \return number of pushed items
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
*/
|
|
template <size_type size>
|
|
size_type push(T const (&t)[size])
|
|
{
|
|
return push(t, size);
|
|
}
|
|
|
|
/** Pushes as many objects from the range [begin, end) as there is space .
|
|
*
|
|
* \pre only one thread is allowed to push data to the spsc_queue
|
|
* \return iterator to the first element, which has not been pushed
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
*/
|
|
template <typename ConstIterator>
|
|
ConstIterator push(ConstIterator begin, ConstIterator end)
|
|
{
|
|
return base_type::push(begin, end);
|
|
}
|
|
|
|
/** Pops a maximum of size objects from ringbuffer.
|
|
*
|
|
* \pre only one thread is allowed to pop data to the spsc_queue
|
|
* \return number of popped items
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
* */
|
|
size_type pop(T * ret, size_type size)
|
|
{
|
|
return base_type::pop(ret, size);
|
|
}
|
|
|
|
/** Pops a maximum of size objects from spsc_queue.
|
|
*
|
|
* \pre only one thread is allowed to pop data to the spsc_queue
|
|
* \return number of popped items
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
* */
|
|
template <size_type size>
|
|
size_type pop(T (&ret)[size])
|
|
{
|
|
return pop(ret, size);
|
|
}
|
|
|
|
/** Pops objects to the output iterator it
|
|
*
|
|
* \pre only one thread is allowed to pop data to the spsc_queue
|
|
* \return number of popped items
|
|
*
|
|
* \note Thread-safe and wait-free
|
|
* */
|
|
template <typename OutputIterator>
|
|
size_type pop(OutputIterator it)
|
|
{
|
|
return base_type::pop(it);
|
|
}
|
|
|
|
/** consumes one element via a functor
|
|
*
|
|
* pops one element from the queue and applies the functor on this object
|
|
*
|
|
* \returns true, if one element was consumed
|
|
*
|
|
* \note Thread-safe and non-blocking, if functor is thread-safe and non-blocking
|
|
* */
|
|
template <typename Functor>
|
|
bool consume_one(Functor & f)
|
|
{
|
|
T element;
|
|
bool success = pop(element);
|
|
if (success)
|
|
f(element);
|
|
|
|
return success;
|
|
}
|
|
|
|
/// \copydoc boost::lockfree::spsc_queue::consume_one(Functor & rhs)
|
|
template <typename Functor>
|
|
bool consume_one(Functor const & f)
|
|
{
|
|
T element;
|
|
bool success = pop(element);
|
|
if (success)
|
|
f(element);
|
|
|
|
return success;
|
|
}
|
|
|
|
/** consumes all elements via a functor
|
|
*
|
|
* sequentially pops all elements from the queue and applies the functor on each object
|
|
*
|
|
* \returns number of elements that are consumed
|
|
*
|
|
* \note Thread-safe and non-blocking, if functor is thread-safe and non-blocking
|
|
* */
|
|
template <typename Functor>
|
|
size_type consume_all(Functor & f)
|
|
{
|
|
size_type element_count = 0;
|
|
while (consume_one(f))
|
|
element_count += 1;
|
|
|
|
return element_count;
|
|
}
|
|
|
|
/// \copydoc boost::lockfree::spsc_queue::consume_all(Functor & rhs)
|
|
template <typename Functor>
|
|
size_type consume_all(Functor const & f)
|
|
{
|
|
size_type element_count = 0;
|
|
while (consume_one(f))
|
|
element_count += 1;
|
|
|
|
return element_count;
|
|
}
|
|
};
|
|
|
|
} /* namespace lockfree */
|
|
} /* namespace boost */
|
|
|
|
|
|
#endif /* BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED */
|