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 //  lock-free single-producer/single-consumer ringbuffer
 //  this algorithm is implemented in various projects (linux kernel)
 //
 //  Copyright (C) 2009-2013 Tim Blechmann
 //
 //  Distributed under the Boost Software License, Version 1.0. (See
 //  accompanying file LICENSE_1_0.txt or copy at
 //  http://www.boost.org/LICENSE_1_0.txt)
 
 #ifndef BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED
 #define BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED
 
 #include <algorithm>
 #include <memory>
 
 #include <boost/aligned_storage.hpp>
 #include <boost/assert.hpp>
 #include <boost/static_assert.hpp>
 #include <boost/core/allocator_access.hpp>
 #include <boost/utility.hpp>
 #include <boost/next_prior.hpp>
 #include <boost/utility/enable_if.hpp>
 #include <boost/config.hpp> // for BOOST_LIKELY
 
 #include <boost/type_traits/has_trivial_destructor.hpp>
 #include <boost/type_traits/is_convertible.hpp>
 
 #include <boost/lockfree/detail/atomic.hpp>
 #include <boost/lockfree/detail/copy_payload.hpp>
 #include <boost/lockfree/detail/parameter.hpp>
 #include <boost/lockfree/detail/prefix.hpp>
 
 #include <boost/lockfree/lockfree_forward.hpp>
 
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #pragma once
 #endif
 
 namespace boost    {
 namespace lockfree {
 namespace detail   {
 
 typedef parameter::parameters<boost::parameter::optional<tag::capacity>,
                               boost::parameter::optional<tag::allocator>
                              > ringbuffer_signature;
 
 template <typename T>
 class ringbuffer_base
 {
 #ifndef BOOST_DOXYGEN_INVOKED
 protected:
     typedef std::size_t size_t;
     static const int padding_size = BOOST_LOCKFREE_CACHELINE_BYTES - sizeof(size_t);
     atomic<size_t> write_index_;
     char padding1[padding_size]; /* force read_index and write_index to different cache lines */
     atomic<size_t> read_index_;
 
     BOOST_DELETED_FUNCTION(ringbuffer_base(ringbuffer_base const&))
     BOOST_DELETED_FUNCTION(ringbuffer_base& operator= (ringbuffer_base const&))
 
 protected:
     ringbuffer_base(void):
         write_index_(0), read_index_(0)
     {}
 
     static size_t next_index(size_t arg, size_t max_size)
     {
         size_t ret = arg + 1;
         while (BOOST_UNLIKELY(ret >= max_size))
             ret -= max_size;
         return ret;
     }
 
     static size_t read_available(size_t write_index, size_t read_index, size_t max_size)
     {
         if (write_index >= read_index)
             return write_index - read_index;
 
         const size_t ret = write_index + max_size - read_index;
         return ret;
     }
 
     static size_t write_available(size_t write_index, size_t read_index, size_t max_size)
     {
         size_t ret = read_index - write_index - 1;
         if (write_index >= read_index)
             ret += max_size;
         return ret;
     }
 
     size_t read_available(size_t max_size) const
     {
         size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index  = read_index_.load(memory_order_relaxed);
         return read_available(write_index, read_index, max_size);
     }
 
     size_t write_available(size_t max_size) const
     {
         size_t write_index = write_index_.load(memory_order_relaxed);
         const size_t read_index  = read_index_.load(memory_order_acquire);
         return write_available(write_index, read_index, max_size);
     }
 
     bool push(T const & t, T * buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_relaxed);  // only written from push thread
         const size_t next = next_index(write_index, max_size);
 
         if (next == read_index_.load(memory_order_acquire))
             return false; /* ringbuffer is full */
 
         new (buffer + write_index) T(t); // copy-construct
 
         write_index_.store(next, memory_order_release);
 
         return true;
     }
 
     size_t push(const T * input_buffer, size_t input_count, T * internal_buffer, size_t max_size)
     {
         return push(input_buffer, input_buffer + input_count, internal_buffer, max_size) - input_buffer;
     }
 
     template <typename ConstIterator>
     ConstIterator push(ConstIterator begin, ConstIterator end, T * internal_buffer, size_t max_size)
     {
         // FIXME: avoid std::distance
 
         const size_t write_index = write_index_.load(memory_order_relaxed);  // only written from push thread
         const size_t read_index  = read_index_.load(memory_order_acquire);
         const size_t avail = write_available(write_index, read_index, max_size);
 
         if (avail == 0)
             return begin;
 
         size_t input_count = std::distance(begin, end);
         input_count = (std::min)(input_count, avail);
 
         size_t new_write_index = write_index + input_count;
 
         const ConstIterator last = boost::next(begin, input_count);
 
         if (write_index + input_count > max_size) {
             /* copy data in two sections */
             const size_t count0 = max_size - write_index;
             const ConstIterator midpoint = boost::next(begin, count0);
 
             std::uninitialized_copy(begin, midpoint, internal_buffer + write_index);
             std::uninitialized_copy(midpoint, last, internal_buffer);
             new_write_index -= max_size;
         } else {
             std::uninitialized_copy(begin, last, internal_buffer + write_index);
 
             if (new_write_index == max_size)
                 new_write_index = 0;
         }
 
         write_index_.store(new_write_index, memory_order_release);
         return last;
     }
 
     template <typename Functor>
     bool consume_one(Functor & functor, T * buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index  = read_index_.load(memory_order_relaxed); // only written from pop thread
         if ( empty(write_index, read_index) )
             return false;
 
         T & object_to_consume = buffer[read_index];
         functor( object_to_consume );
         object_to_consume.~T();
 
         size_t next = next_index(read_index, max_size);
         read_index_.store(next, memory_order_release);
         return true;
     }
 
     template <typename Functor>
     bool consume_one(Functor const & functor, T * buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index  = read_index_.load(memory_order_relaxed); // only written from pop thread
         if ( empty(write_index, read_index) )
             return false;
 
         T & object_to_consume = buffer[read_index];
         functor( object_to_consume );
         object_to_consume.~T();
 
         size_t next = next_index(read_index, max_size);
         read_index_.store(next, memory_order_release);
         return true;
     }
 
     template <typename Functor>
     size_t consume_all (Functor const & functor, T * internal_buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
 
         const size_t avail = read_available(write_index, read_index, max_size);
 
         if (avail == 0)
             return 0;
 
         const size_t output_count = avail;
 
         size_t new_read_index = read_index + output_count;
 
         if (read_index + output_count > max_size) {
             /* copy data in two sections */
             const size_t count0 = max_size - read_index;
             const size_t count1 = output_count - count0;
 
             run_functor_and_delete(internal_buffer + read_index, internal_buffer + max_size, functor);
             run_functor_and_delete(internal_buffer, internal_buffer + count1, functor);
 
             new_read_index -= max_size;
         } else {
             run_functor_and_delete(internal_buffer + read_index, internal_buffer + read_index + output_count, functor);
 
             if (new_read_index == max_size)
                 new_read_index = 0;
         }
 
         read_index_.store(new_read_index, memory_order_release);
         return output_count;
     }
 
     template <typename Functor>
     size_t consume_all (Functor & functor, T * internal_buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
 
         const size_t avail = read_available(write_index, read_index, max_size);
 
         if (avail == 0)
             return 0;
 
         const size_t output_count = avail;
 
         size_t new_read_index = read_index + output_count;
 
         if (read_index + output_count > max_size) {
             /* copy data in two sections */
             const size_t count0 = max_size - read_index;
             const size_t count1 = output_count - count0;
 
             run_functor_and_delete(internal_buffer + read_index, internal_buffer + max_size, functor);
             run_functor_and_delete(internal_buffer, internal_buffer + count1, functor);
 
             new_read_index -= max_size;
         } else {
             run_functor_and_delete(internal_buffer + read_index, internal_buffer + read_index + output_count, functor);
 
             if (new_read_index == max_size)
                 new_read_index = 0;
         }
 
         read_index_.store(new_read_index, memory_order_release);
         return output_count;
     }
 
     size_t pop (T * output_buffer, size_t output_count, T * internal_buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
 
         const size_t avail = read_available(write_index, read_index, max_size);
 
         if (avail == 0)
             return 0;
 
         output_count = (std::min)(output_count, avail);
 
         size_t new_read_index = read_index + output_count;
 
         if (read_index + output_count > max_size) {
             /* copy data in two sections */
             const size_t count0 = max_size - read_index;
             const size_t count1 = output_count - count0;
 
             copy_and_delete(internal_buffer + read_index, internal_buffer + max_size, output_buffer);
             copy_and_delete(internal_buffer, internal_buffer + count1, output_buffer + count0);
 
             new_read_index -= max_size;
         } else {
             copy_and_delete(internal_buffer + read_index, internal_buffer + read_index + output_count, output_buffer);
             if (new_read_index == max_size)
                 new_read_index = 0;
         }
 
         read_index_.store(new_read_index, memory_order_release);
         return output_count;
     }
 
     template <typename OutputIterator>
     size_t pop_to_output_iterator (OutputIterator it, T * internal_buffer, size_t max_size)
     {
         const size_t write_index = write_index_.load(memory_order_acquire);
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
 
         const size_t avail = read_available(write_index, read_index, max_size);
         if (avail == 0)
             return 0;
 
         size_t new_read_index = read_index + avail;
 
         if (read_index + avail > max_size) {
             /* copy data in two sections */
             const size_t count0 = max_size - read_index;
             const size_t count1 = avail - count0;
 
             it = copy_and_delete(internal_buffer + read_index, internal_buffer + max_size, it);
             copy_and_delete(internal_buffer, internal_buffer + count1, it);
 
             new_read_index -= max_size;
         } else {
             copy_and_delete(internal_buffer + read_index, internal_buffer + read_index + avail, it);
             if (new_read_index == max_size)
                 new_read_index = 0;
         }
 
         read_index_.store(new_read_index, memory_order_release);
         return avail;
     }
 
     const T& front(const T * internal_buffer) const
     {
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
         return *(internal_buffer + read_index);
     }
 
     T& front(T * internal_buffer)
     {
         const size_t read_index = read_index_.load(memory_order_relaxed); // only written from pop thread
         return *(internal_buffer + read_index);
     }
 #endif
 
 
 public:
     /** reset the ringbuffer
      *
      * \note Not thread-safe
      * */
     void reset(void)
     {
         if ( !boost::has_trivial_destructor<T>::value ) {
             // make sure to call all destructors!
 
             detail::consume_noop consume_functor;
             (void)consume_all( consume_functor );
         } else {
             write_index_.store(0, memory_order_relaxed);
             read_index_.store(0, memory_order_release);
         }
     }
 
     /** Check if the ringbuffer is empty
      *
      * \return true, if the ringbuffer is empty, false otherwise
      * \note Due to the concurrent nature of the ringbuffer the result may be inaccurate.
      * */
     bool empty(void)
     {
         return empty(write_index_.load(memory_order_relaxed), read_index_.load(memory_order_relaxed));
     }
 
     /**
      * \return true, if implementation is lock-free.
      *
      * */
     bool is_lock_free(void) const
     {
         return write_index_.is_lock_free() && read_index_.is_lock_free();
     }
 
 private:
     bool empty(size_t write_index, size_t read_index)
     {
         return write_index == read_index;
     }
 
     template< class OutputIterator >
     OutputIterator copy_and_delete( T * first, T * last, OutputIterator out )
     {
         if (boost::has_trivial_destructor<T>::value) {
             return std::copy(first, last, out); // will use memcpy if possible
         } else {
             for (; first != last; ++first, ++out) {
                 *out = *first;
                 first->~T();
             }
             return out;
         }
     }
 
     template< class Functor >
     void run_functor_and_delete( T * first, T * last, Functor & functor )
     {
         for (; first != last; ++first) {
             functor(*first);
             first->~T();
         }
     }
 
     template< class Functor >
     void run_functor_and_delete( T * first, T * last, Functor const & functor )
     {
         for (; first != last; ++first) {
             functor(*first);
             first->~T();
         }
     }
 };
 
 template <typename T, std::size_t MaxSize>
 class compile_time_sized_ringbuffer:
     public ringbuffer_base<T>
 {
     typedef std::size_t size_type;
     static const std::size_t max_size = MaxSize + 1;
 
     typedef typename boost::aligned_storage<max_size * sizeof(T),
                                             boost::alignment_of<T>::value
                                            >::type storage_type;
 
     storage_type storage_;
 
     T * data()
     {
         return static_cast<T*>(storage_.address());
     }
 
     const T * data() const
     {
         return static_cast<const T*>(storage_.address());
     }
 
 protected:
     size_type max_number_of_elements() const
     {
         return max_size;
     }
 
     ~compile_time_sized_ringbuffer(void)
     {
         // destroy all remaining items
         detail::consume_noop consume_functor;
         (void)consume_all(consume_functor);
     }
 
 public:
     bool push(T const & t)
     {
         return ringbuffer_base<T>::push(t, data(), max_size);
     }
 
     template <typename Functor>
     bool consume_one(Functor & f)
     {
         return ringbuffer_base<T>::consume_one(f, data(), max_size);
     }
 
     template <typename Functor>
     bool consume_one(Functor const & f)
     {
         return ringbuffer_base<T>::consume_one(f, data(), max_size);
     }
 
     template <typename Functor>
     size_type consume_all(Functor & f)
     {
         return ringbuffer_base<T>::consume_all(f, data(), max_size);
     }
 
     template <typename Functor>
     size_type consume_all(Functor const & f)
     {
         return ringbuffer_base<T>::consume_all(f, data(), max_size);
     }
 
     size_type push(T const * t, size_type size)
     {
         return ringbuffer_base<T>::push(t, size, data(), max_size);
     }
 
     template <size_type size>
     size_type push(T const (&t)[size])
     {
         return push(t, size);
     }
 
     template <typename ConstIterator>
     ConstIterator push(ConstIterator begin, ConstIterator end)
     {
         return ringbuffer_base<T>::push(begin, end, data(), max_size);
     }
 
     size_type pop(T * ret, size_type size)
     {
         return ringbuffer_base<T>::pop(ret, size, data(), max_size);
     }
 
     template <typename OutputIterator>
     size_type pop_to_output_iterator(OutputIterator it)
     {
         return ringbuffer_base<T>::pop_to_output_iterator(it, data(), max_size);
     }
 
     const T& front(void) const
     {
         return ringbuffer_base<T>::front(data());
     }
 
     T& front(void)
     {
         return ringbuffer_base<T>::front(data());
     }
 };
 
 template <typename T, typename Alloc>
 class runtime_sized_ringbuffer:
     public ringbuffer_base<T>,
     private Alloc
 {
     typedef std::size_t size_type;
     size_type max_elements_;
 #ifdef BOOST_NO_CXX11_ALLOCATOR
     typedef typename Alloc::pointer pointer;
 #else
     typedef std::allocator_traits<Alloc> allocator_traits;
     typedef typename allocator_traits::pointer pointer;
 #endif
     pointer array_;
 
 protected:
     size_type max_number_of_elements() const
     {
         return max_elements_;
     }
 
 public:
     explicit runtime_sized_ringbuffer(size_type max_elements):
         max_elements_(max_elements + 1)
     {
 #ifdef BOOST_NO_CXX11_ALLOCATOR
         array_ = Alloc::allocate(max_elements_);
 #else
         Alloc& alloc = *this;
         array_ = allocator_traits::allocate(alloc, max_elements_);
 #endif
     }
 
     template <typename U>
     runtime_sized_ringbuffer(typename boost::allocator_rebind<Alloc, U>::type const & alloc, size_type max_elements):
         Alloc(alloc), max_elements_(max_elements + 1)
     {
 #ifdef BOOST_NO_CXX11_ALLOCATOR
         array_ = Alloc::allocate(max_elements_);
 #else
         Alloc& allocator = *this;
         array_ = allocator_traits::allocate(allocator, max_elements_);
 #endif
     }
 
     runtime_sized_ringbuffer(Alloc const & alloc, size_type max_elements):
         Alloc(alloc), max_elements_(max_elements + 1)
     {
 #ifdef BOOST_NO_CXX11_ALLOCATOR
         array_ = Alloc::allocate(max_elements_);
 #else
         Alloc& allocator = *this;
         array_ = allocator_traits::allocate(allocator, max_elements_);
 #endif
     }
 
     ~runtime_sized_ringbuffer(void)
     {
         // destroy all remaining items
         detail::consume_noop consume_functor;
         (void)consume_all(consume_functor);
 
 #ifdef BOOST_NO_CXX11_ALLOCATOR
         Alloc::deallocate(array_, max_elements_);
 #else
         Alloc& allocator = *this;
         allocator_traits::deallocate(allocator, array_, max_elements_);
 #endif
     }
 
     bool push(T const & t)
     {
         return ringbuffer_base<T>::push(t, &*array_, max_elements_);
     }
 
     template <typename Functor>
     bool consume_one(Functor & f)
     {
         return ringbuffer_base<T>::consume_one(f, &*array_, max_elements_);
     }
 
     template <typename Functor>
     bool consume_one(Functor const & f)
     {
         return ringbuffer_base<T>::consume_one(f, &*array_, max_elements_);
     }
 
     template <typename Functor>
     size_type consume_all(Functor & f)
     {
         return ringbuffer_base<T>::consume_all(f, &*array_, max_elements_);
     }
 
     template <typename Functor>
     size_type consume_all(Functor const & f)
     {
         return ringbuffer_base<T>::consume_all(f, &*array_, max_elements_);
     }
 
     size_type push(T const * t, size_type size)
     {
         return ringbuffer_base<T>::push(t, size, &*array_, max_elements_);
     }
 
     template <size_type size>
     size_type push(T const (&t)[size])
     {
         return push(t, size);
     }
 
     template <typename ConstIterator>
     ConstIterator push(ConstIterator begin, ConstIterator end)
     {
         return ringbuffer_base<T>::push(begin, end, &*array_, max_elements_);
     }
 
     size_type pop(T * ret, size_type size)
     {
         return ringbuffer_base<T>::pop(ret, size, &*array_, max_elements_);
     }
 
     template <typename OutputIterator>
     size_type pop_to_output_iterator(OutputIterator it)
     {
         return ringbuffer_base<T>::pop_to_output_iterator(it, &*array_, max_elements_);
     }
 
     const T& front(void) const
     {
         return ringbuffer_base<T>::front(&*array_);
     }
 
     T& front(void)
     {
         return ringbuffer_base<T>::front(&*array_);
     }
 };
 
 #ifdef BOOST_NO_CXX11_VARIADIC_TEMPLATES
 template <typename T, typename A0, typename A1>
 #else
 template <typename T, typename ...Options>
 #endif
 struct make_ringbuffer
 {
 #ifdef BOOST_NO_CXX11_VARIADIC_TEMPLATES
     typedef typename ringbuffer_signature::bind<A0, A1>::type bound_args;
 #else
     typedef typename ringbuffer_signature::bind<Options...>::type bound_args;
 #endif
 
     typedef extract_capacity<bound_args> extract_capacity_t;
 
     static const bool runtime_sized = !extract_capacity_t::has_capacity;
     static const size_t capacity    =  extract_capacity_t::capacity;
 
     typedef extract_allocator<bound_args, T> extract_allocator_t;
     typedef typename extract_allocator_t::type allocator;
 
     // allocator argument is only sane, for run-time sized ringbuffers
     BOOST_STATIC_ASSERT((mpl::if_<mpl::bool_<!runtime_sized>,
                                   mpl::bool_<!extract_allocator_t::has_allocator>,
                                   mpl::true_
                                  >::type::value));
 
     typedef typename mpl::if_c<runtime_sized,
                                runtime_sized_ringbuffer<T, allocator>,
                                compile_time_sized_ringbuffer<T, capacity>
                               >::type ringbuffer_type;
 };
 
 
 } /* namespace detail */
 
 
 /** The spsc_queue class provides a single-writer/single-reader fifo queue, pushing and popping is wait-free.
  *
  *  \b Policies:
  *  - \c boost::lockfree::capacity<>, optional <br>
  *    If this template argument is passed to the options, the size of the ringbuffer is set at compile-time.
  *
  *  - \c boost::lockfree::allocator<>, defaults to \c boost::lockfree::allocator<std::allocator<T>> <br>
  *    Specifies the allocator that is used to allocate the ringbuffer. This option is only valid, if the ringbuffer is configured
  *    to be sized at run-time
  *
  *  \b Requirements:
  *  - T must have a default constructor
  *  - T must be copyable
  * */
 #ifdef BOOST_NO_CXX11_VARIADIC_TEMPLATES
 template <typename T, class A0, class A1>
 #else
 template <typename T, typename ...Options>
 #endif
 class spsc_queue:
 #ifdef BOOST_NO_CXX11_VARIADIC_TEMPLATES
     public detail::make_ringbuffer<T, A0, A1>::ringbuffer_type
 #else
     public detail::make_ringbuffer<T, Options...>::ringbuffer_type
 #endif
 {
 private:
 
 #ifndef BOOST_DOXYGEN_INVOKED
 
 #ifdef BOOST_NO_CXX11_VARIADIC_TEMPLATES
     typedef typename detail::make_ringbuffer<T, A0, A1>::ringbuffer_type base_type;
     static const bool runtime_sized = detail::make_ringbuffer<T, A0, A1>::runtime_sized;
     typedef typename detail::make_ringbuffer<T, A0, A1>::allocator allocator_arg;
 #else
     typedef typename detail::make_ringbuffer<T, Options...>::ringbuffer_type base_type;
     static const bool runtime_sized = detail::make_ringbuffer<T, Options...>::runtime_sized;
     typedef typename detail::make_ringbuffer<T, Options...>::allocator allocator_arg;
 #endif
 
 
     struct implementation_defined
     {
         typedef allocator_arg allocator;
         typedef std::size_t size_type;
     };
 #endif
 
 public:
     typedef T value_type;
     typedef typename implementation_defined::allocator allocator;
     typedef typename implementation_defined::size_type size_type;
 
     /** Constructs a spsc_queue
      *
      *  \pre spsc_queue must be configured to be sized at compile-time
      */
     spsc_queue(void)
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling
         // this function and this function may be compiled even when it isn't being used.
         BOOST_ASSERT(!runtime_sized);
     }
 
     /** Constructs a spsc_queue with a custom allocator
      *
      *  \pre spsc_queue must be configured to be sized at compile-time
      *
      *  \note This is just for API compatibility: an allocator isn't actually needed
      */
     template <typename U>
     explicit spsc_queue(typename boost::allocator_rebind<allocator, U>::type const &)
     {
         BOOST_STATIC_ASSERT(!runtime_sized);
     }
 
     /** Constructs a spsc_queue with a custom allocator
      *
      *  \pre spsc_queue must be configured to be sized at compile-time
      *
      *  \note This is just for API compatibility: an allocator isn't actually needed
      */
     explicit spsc_queue(allocator const &)
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling
         // this function and this function may be compiled even when it isn't being used.
         BOOST_ASSERT(!runtime_sized);
     }
 
     /** 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)
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling
         // this function and this function may be compiled even when it isn't being used.
         BOOST_ASSERT(runtime_sized);
     }
 
     /** Constructs a spsc_queue for element_count elements with a custom allocator
      *
      *  \pre spsc_queue must be configured to be sized at run-time
      */
     template <typename U>
     spsc_queue(size_type element_count, typename boost::allocator_rebind<allocator, U>::type const & alloc):
         base_type(alloc, element_count)
     {
         BOOST_STATIC_ASSERT(runtime_sized);
     }
 
     /** Constructs a spsc_queue for element_count elements with a custom allocator
      *
      *  \pre spsc_queue must be configured to be sized at run-time
      */
     spsc_queue(size_type element_count, allocator_arg const & alloc):
         base_type(alloc, element_count)
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling
         // this function and this function may be compiled even when it isn't being used.
         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 discarded.
      * \return true, if the pop operation is successful, false if ringbuffer was empty.
      *
      * \note Thread-safe and wait-free
      */
     bool pop ()
     {
         detail::consume_noop consume_functor;
         return consume_one( consume_functor );
     }
 
     /** 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
      */
     template <typename U>
     typename boost::enable_if<typename is_convertible<T, U>::type, bool>::type
     pop (U & ret)
     {
         detail::consume_via_copy<U> consume_functor(ret);
         return consume_one( consume_functor );
     }
 
     /** 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>
     typename boost::disable_if<typename is_convertible<T, OutputIterator>::type, size_type>::type
     pop(OutputIterator it)
     {
         return base_type::pop_to_output_iterator(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)
     {
         return base_type::consume_one(f);
     }
 
     /// \copydoc boost::lockfree::spsc_queue::consume_one(Functor & rhs)
     template <typename Functor>
     bool consume_one(Functor const & f)
     {
         return base_type::consume_one(f);
     }
 
     /** 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)
     {
         return base_type::consume_all(f);
     }
 
     /// \copydoc boost::lockfree::spsc_queue::consume_all(Functor & rhs)
     template <typename Functor>
     size_type consume_all(Functor const & f)
     {
         return base_type::consume_all(f);
     }
 
     /** get number of elements that are available for read
      *
      * \return number of available elements that can be popped from the spsc_queue
      *
      * \note Thread-safe and wait-free, should only be called from the consumer thread
      * */
     size_type read_available() const
     {
         return base_type::read_available(base_type::max_number_of_elements());
     }
 
     /** get write space to write elements
      *
      * \return number of elements that can be pushed to the spsc_queue
      *
      * \note Thread-safe and wait-free, should only be called from the producer thread
      * */
     size_type write_available() const
     {
         return base_type::write_available(base_type::max_number_of_elements());
     }
 
     /** get reference to element in the front of the queue
      *
      * Availability of front element can be checked using read_available().
      *
      * \pre only a consuming thread is allowed to check front element
      * \pre read_available() > 0. If ringbuffer is empty, it's undefined behaviour to invoke this method.
      * \return reference to the first element in the queue
      *
      * \note Thread-safe and wait-free
      */
     const T& front() const
     {
         BOOST_ASSERT(read_available() > 0);
         return base_type::front();
     }
 
     /// \copydoc boost::lockfree::spsc_queue::front() const
     T& front()
     {
         BOOST_ASSERT(read_available() > 0);
         return base_type::front();
     }
 
     /** reset the ringbuffer
      *
      * \note Not thread-safe
      * */
     void reset(void)
     {
         if ( !boost::has_trivial_destructor<T>::value ) {
             // make sure to call all destructors!
 
             detail::consume_noop consume_functor;
             (void)consume_all(consume_functor);
         } else {
             base_type::write_index_.store(0, memory_order_relaxed);
             base_type::read_index_.store(0, memory_order_release);
         }
    }
 };
 
 } /* namespace lockfree */
 } /* namespace boost */
 
 
 #endif /* BOOST_LOCKFREE_SPSC_QUEUE_HPP_INCLUDED */

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