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// Copyright Oliver Kowalke 2016.
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// Distributed under the Boost Software License, Version 1.0.
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// (See 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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//
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#ifndef BOOST_FIBERS_BUFFERED_CHANNEL_H
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#define BOOST_FIBERS_BUFFERED_CHANNEL_H
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#include <atomic>
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#include <chrono>
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <type_traits>
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#include <boost/config.hpp>
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#include <boost/fiber/channel_op_status.hpp>
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#include <boost/fiber/context.hpp>
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#include <boost/fiber/waker.hpp>
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#include <boost/fiber/detail/config.hpp>
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#include <boost/fiber/detail/convert.hpp>
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#include <boost/fiber/detail/spinlock.hpp>
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#include <boost/fiber/exceptions.hpp>
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_PREFIX
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#endif
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namespace boost {
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namespace fibers {
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template< typename T >
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class buffered_channel {
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public:
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using value_type = typename std::remove_reference<T>::type;
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private:
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using slot_type = value_type;
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mutable detail::spinlock splk_{};
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wait_queue waiting_producers_{};
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wait_queue waiting_consumers_{};
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slot_type * slots_;
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std::size_t pidx_{ 0 };
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std::size_t cidx_{ 0 };
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std::size_t capacity_;
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bool closed_{ false };
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bool is_full_() const noexcept {
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return cidx_ == ((pidx_ + 1) % capacity_);
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}
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bool is_empty_() const noexcept {
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return cidx_ == pidx_;
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}
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bool is_closed_() const noexcept {
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return closed_;
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}
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public:
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explicit buffered_channel( std::size_t capacity) :
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capacity_{ capacity } {
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if ( BOOST_UNLIKELY( 2 > capacity_ || 0 != ( capacity_ & (capacity_ - 1) ) ) ) {
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throw fiber_error{ std::make_error_code( std::errc::invalid_argument),
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"boost fiber: buffer capacity is invalid" };
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}
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slots_ = new slot_type[capacity_];
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}
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~buffered_channel() {
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close();
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delete [] slots_;
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}
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buffered_channel( buffered_channel const&) = delete;
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buffered_channel & operator=( buffered_channel const&) = delete;
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bool is_closed() const noexcept {
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detail::spinlock_lock lk{ splk_ };
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return is_closed_();
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}
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void close() noexcept {
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detail::spinlock_lock lk{ splk_ };
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if ( ! closed_) {
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closed_ = true;
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waiting_producers_.notify_all();
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waiting_consumers_.notify_all();
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}
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}
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channel_op_status try_push( value_type const& value) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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return channel_op_status::full;
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}
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slots_[pidx_] = value;
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pidx_ = (pidx_ + 1) % capacity_;
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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channel_op_status try_push( value_type && value) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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return channel_op_status::full;
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}
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slots_[pidx_] = std::move( value);
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pidx_ = (pidx_ + 1) % capacity_;
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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channel_op_status push( value_type const& value) {
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context * active_ctx = context::active();
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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waiting_producers_.suspend_and_wait( lk, active_ctx);
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} else {
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slots_[pidx_] = value;
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pidx_ = (pidx_ + 1) % capacity_;
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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channel_op_status push( value_type && value) {
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context * active_ctx = context::active();
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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waiting_producers_.suspend_and_wait( lk, active_ctx);
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} else {
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slots_[pidx_] = std::move( value);
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pidx_ = (pidx_ + 1) % capacity_;
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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template< typename Rep, typename Period >
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channel_op_status push_wait_for( value_type const& value,
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std::chrono::duration< Rep, Period > const& timeout_duration) {
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return push_wait_until( value,
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std::chrono::steady_clock::now() + timeout_duration);
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}
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template< typename Rep, typename Period >
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channel_op_status push_wait_for( value_type && value,
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std::chrono::duration< Rep, Period > const& timeout_duration) {
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return push_wait_until( std::forward< value_type >( value),
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std::chrono::steady_clock::now() + timeout_duration);
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}
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template< typename Clock, typename Duration >
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channel_op_status push_wait_until( value_type const& value,
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std::chrono::time_point< Clock, Duration > const& timeout_time_) {
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context * active_ctx = context::active();
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std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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if ( ! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
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return channel_op_status::timeout;
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}
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} else {
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slots_[pidx_] = value;
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pidx_ = (pidx_ + 1) % capacity_;
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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template< typename Clock, typename Duration >
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channel_op_status push_wait_until( value_type && value,
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std::chrono::time_point< Clock, Duration > const& timeout_time_) {
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context * active_ctx = context::active();
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std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( is_full_() ) {
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if ( ! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
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return channel_op_status::timeout;
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}
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} else {
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slots_[pidx_] = std::move( value);
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pidx_ = (pidx_ + 1) % capacity_;
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// notify one waiting consumer
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waiting_consumers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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channel_op_status try_pop( value_type & value) {
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detail::spinlock_lock lk{ splk_ };
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if ( is_empty_() ) {
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return is_closed_()
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? channel_op_status::closed
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: channel_op_status::empty;
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}
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value = std::move( slots_[cidx_]);
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cidx_ = (cidx_ + 1) % capacity_;
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waiting_producers_.notify_one();
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return channel_op_status::success;
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}
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channel_op_status pop( value_type & value) {
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context * active_ctx = context::active();
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( is_empty_() ) {
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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waiting_consumers_.suspend_and_wait( lk, active_ctx);
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} else {
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value = std::move( slots_[cidx_]);
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cidx_ = (cidx_ + 1) % capacity_;
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waiting_producers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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value_type value_pop() {
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context * active_ctx = context::active();
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( is_empty_() ) {
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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throw fiber_error{
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std::make_error_code( std::errc::operation_not_permitted),
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"boost fiber: channel is closed" };
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}
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waiting_consumers_.suspend_and_wait( lk, active_ctx);
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} else {
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value_type value = std::move( slots_[cidx_]);
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cidx_ = (cidx_ + 1) % capacity_;
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waiting_producers_.notify_one();
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return value;
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}
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}
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}
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template< typename Rep, typename Period >
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channel_op_status pop_wait_for( value_type & value,
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std::chrono::duration< Rep, Period > const& timeout_duration) {
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return pop_wait_until( value,
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std::chrono::steady_clock::now() + timeout_duration);
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}
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template< typename Clock, typename Duration >
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channel_op_status pop_wait_until( value_type & value,
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std::chrono::time_point< Clock, Duration > const& timeout_time_) {
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context * active_ctx = context::active();
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std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
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for (;;) {
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detail::spinlock_lock lk{ splk_ };
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if ( is_empty_() ) {
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if ( BOOST_UNLIKELY( is_closed_() ) ) {
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return channel_op_status::closed;
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}
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if ( ! waiting_consumers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
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return channel_op_status::timeout;
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}
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} else {
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value = std::move( slots_[cidx_]);
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cidx_ = (cidx_ + 1) % capacity_;
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waiting_producers_.notify_one();
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return channel_op_status::success;
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}
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}
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}
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class iterator {
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private:
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typedef typename std::aligned_storage< sizeof( value_type), alignof( value_type) >::type storage_type;
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buffered_channel * chan_{ nullptr };
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storage_type storage_;
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void increment_( bool initial = false) {
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BOOST_ASSERT( nullptr != chan_);
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try {
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if ( ! initial) {
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reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
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}
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::new ( static_cast< void * >( std::addressof( storage_) ) ) value_type{ chan_->value_pop() };
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} catch ( fiber_error const&) {
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chan_ = nullptr;
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}
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}
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public:
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using iterator_category = std::input_iterator_tag;
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using difference_type = std::ptrdiff_t;
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using pointer = value_type *;
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using reference = value_type &;
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using pointer_t = pointer;
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using reference_t = reference;
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iterator() noexcept = default;
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explicit iterator( buffered_channel< T > * chan) noexcept :
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chan_{ chan } {
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increment_( true);
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}
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iterator( iterator const& other) noexcept :
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chan_{ other.chan_ } {
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}
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iterator & operator=( iterator const& other) noexcept {
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if ( BOOST_LIKELY( this != & other) ) {
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chan_ = other.chan_;
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}
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return * this;
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}
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bool operator==( iterator const& other) const noexcept {
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return other.chan_ == chan_;
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}
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bool operator!=( iterator const& other) const noexcept {
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return other.chan_ != chan_;
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}
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iterator & operator++() {
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reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
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increment_();
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return * this;
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}
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const iterator operator++( int) = delete;
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reference_t operator*() noexcept {
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return * reinterpret_cast< value_type * >( std::addressof( storage_) );
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}
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pointer_t operator->() noexcept {
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return reinterpret_cast< value_type * >( std::addressof( storage_) );
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}
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};
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friend class iterator;
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};
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template< typename T >
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typename buffered_channel< T >::iterator
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begin( buffered_channel< T > & chan) {
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return typename buffered_channel< T >::iterator( & chan);
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}
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template< typename T >
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typename buffered_channel< T >::iterator
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end( buffered_channel< T > &) {
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return typename buffered_channel< T >::iterator();
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}
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}}
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_SUFFIX
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#endif
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#endif // BOOST_FIBERS_BUFFERED_CHANNEL_H
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