485 lines
16 KiB
C++
485 lines
16 KiB
C++
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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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#ifndef BOOST_FIBERS_UNBUFFERED_CHANNEL_H
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#define BOOST_FIBERS_UNBUFFERED_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 <vector>
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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/detail/config.hpp>
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#include <boost/fiber/detail/convert.hpp>
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#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
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#include <boost/fiber/detail/exchange.hpp>
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#endif
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#include <boost/fiber/detail/spinlock.hpp>
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#include <boost/fiber/exceptions.hpp>
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#include <boost/fiber/waker.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 unbuffered_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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struct slot {
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value_type value;
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waker w;
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slot( value_type const& value_, waker && w) :
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value{ value_ },
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w{ std::move(w) } {
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}
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slot( value_type && value_, waker && w) :
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value{ std::move( value_) },
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w{ std::move(w) } {
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}
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};
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// shared cacheline
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std::atomic< slot * > slot_{ nullptr };
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// shared cacheline
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std::atomic_bool closed_{ false };
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mutable detail::spinlock splk_producers_{};
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wait_queue waiting_producers_{};
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mutable detail::spinlock splk_consumers_{};
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wait_queue waiting_consumers_{};
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char pad_[cacheline_length];
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bool is_empty_() {
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return nullptr == slot_.load( std::memory_order_acquire);
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}
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bool try_push_( slot * own_slot) {
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for (;;) {
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slot * s = slot_.load( std::memory_order_acquire);
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if ( nullptr == s) {
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if ( ! slot_.compare_exchange_strong( s, own_slot, std::memory_order_acq_rel) ) {
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continue;
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}
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return true;
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}
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return false;
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}
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}
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slot * try_pop_() {
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slot * nil_slot = nullptr;
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for (;;) {
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slot * s = slot_.load( std::memory_order_acquire);
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if ( nullptr != s) {
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if ( ! slot_.compare_exchange_strong( s, nil_slot, std::memory_order_acq_rel) ) {
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continue;}
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}
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return s;
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}
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}
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public:
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unbuffered_channel() = default;
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~unbuffered_channel() {
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close();
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}
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unbuffered_channel( unbuffered_channel const&) = delete;
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unbuffered_channel & operator=( unbuffered_channel const&) = delete;
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bool is_closed() const noexcept {
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return closed_.load( std::memory_order_acquire);
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}
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void close() noexcept {
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// set flag
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if ( ! closed_.exchange( true, std::memory_order_acquire) ) {
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// notify current waiting
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slot * s = slot_.load( std::memory_order_acquire);
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if ( nullptr != s) {
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// notify context
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s->w.wake();
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}
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detail::spinlock_lock lk1{ splk_producers_ };
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waiting_producers_.notify_all();
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detail::spinlock_lock lk2{ splk_consumers_ };
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waiting_consumers_.notify_all();
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}
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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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slot s{ value, {} };
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for (;;) {
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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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s.w = active_ctx->create_waker();
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_consumers_ };
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waiting_consumers_.notify_one();
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// suspend till value has been consumed
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active_ctx->suspend( lk);
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// resumed
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if ( BOOST_UNLIKELY( is_closed() ) ) {
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// channel was closed before value was consumed
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return channel_op_status::closed;
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}
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// value has been consumed
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return channel_op_status::success;
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}
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detail::spinlock_lock lk{ splk_producers_ };
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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_empty_() ) {
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continue;
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}
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waiting_producers_.suspend_and_wait( lk, active_ctx);
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// resumed, slot mabye free
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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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slot s{ std::move( value), {} };
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for (;;) {
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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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s.w = active_ctx->create_waker();
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_consumers_ };
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waiting_consumers_.notify_one();
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// suspend till value has been consumed
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active_ctx->suspend( lk);
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// resumed
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if ( BOOST_UNLIKELY( is_closed() ) ) {
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// channel was closed before value was consumed
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return channel_op_status::closed;
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}
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// value has been consumed
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return channel_op_status::success;
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}
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detail::spinlock_lock lk{ splk_producers_ };
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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_empty_() ) {
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continue;
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}
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waiting_producers_.suspend_and_wait( lk, active_ctx);
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// resumed, slot mabye free
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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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slot s{ value, {} };
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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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if ( BOOST_UNLIKELY( is_closed() ) ) {
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return channel_op_status::closed;
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}
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s.w = active_ctx->create_waker();
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_consumers_ };
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waiting_consumers_.notify_one();
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// suspend this producer
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if ( ! active_ctx->wait_until(timeout_time, lk, waker(s.w))) {
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// clear slot
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slot * nil_slot = nullptr, * own_slot = & s;
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slot_.compare_exchange_strong( own_slot, nil_slot, std::memory_order_acq_rel);
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// resumed, value has not been consumed
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return channel_op_status::timeout;
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}
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// resumed
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if ( BOOST_UNLIKELY( is_closed() ) ) {
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// channel was closed before value was consumed
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return channel_op_status::closed;
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}
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// value has been consumed
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return channel_op_status::success;
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}
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detail::spinlock_lock lk{ splk_producers_ };
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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_empty_() ) {
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continue;
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}
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if (! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time))
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{
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return channel_op_status::timeout;
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}
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// resumed, slot maybe free
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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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slot s{ std::move( value), {} };
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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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if ( BOOST_UNLIKELY( is_closed() ) ) {
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return channel_op_status::closed;
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}
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s.w = active_ctx->create_waker();
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_consumers_ };
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waiting_consumers_.notify_one();
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// suspend this producer
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if ( ! active_ctx->wait_until(timeout_time, lk, waker(s.w))) {
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// clear slot
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slot * nil_slot = nullptr, * own_slot = & s;
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slot_.compare_exchange_strong( own_slot, nil_slot, std::memory_order_acq_rel);
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// resumed, value has not been consumed
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return channel_op_status::timeout;
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}
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// resumed
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if ( BOOST_UNLIKELY( is_closed() ) ) {
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// channel was closed before value was consumed
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return channel_op_status::closed;
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}
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// value has been consumed
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return channel_op_status::success;
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}
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detail::spinlock_lock lk{ splk_producers_ };
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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_empty_() ) {
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continue;
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}
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if (! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time))
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{
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return channel_op_status::timeout;
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}
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// resumed, slot maybe free
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}
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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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slot * s = nullptr;
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for (;;) {
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if ( nullptr != ( s = try_pop_() ) ) {
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{
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detail::spinlock_lock lk{ splk_producers_ };
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waiting_producers_.notify_one();
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}
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value = std::move( s->value);
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// notify context
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s->w.wake();
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return channel_op_status::success;
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}
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detail::spinlock_lock lk{ splk_consumers_ };
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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_empty_() ) {
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continue;
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}
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waiting_consumers_.suspend_and_wait( lk, active_ctx);
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// resumed, slot mabye set
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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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slot * s = nullptr;
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for (;;) {
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if ( nullptr != ( s = try_pop_() ) ) {
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{
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detail::spinlock_lock lk{ splk_producers_ };
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waiting_producers_.notify_one();
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}
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// consume value
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value_type value = std::move( s->value);
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// notify context
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s->w.wake();
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return std::move( value);
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}
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detail::spinlock_lock lk{ splk_consumers_ };
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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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if ( ! is_empty_() ) {
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continue;
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}
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waiting_consumers_.suspend_and_wait( lk, active_ctx);
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// resumed, slot mabye set
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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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slot * s = nullptr;
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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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if ( nullptr != ( s = try_pop_() ) ) {
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{
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detail::spinlock_lock lk{ splk_producers_ };
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waiting_producers_.notify_one();
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}
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// consume value
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|
value = std::move( s->value);
|
||
|
|
// notify context
|
||
|
|
s->w.wake();
|
||
|
|
return channel_op_status::success;
|
||
|
|
}
|
||
|
|
detail::spinlock_lock lk{ splk_consumers_ };
|
||
|
|
if ( BOOST_UNLIKELY( is_closed() ) ) {
|
||
|
|
return channel_op_status::closed;
|
||
|
|
}
|
||
|
|
if ( ! is_empty_() ) {
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
if ( ! waiting_consumers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
|
||
|
|
return channel_op_status::timeout;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
class iterator {
|
||
|
|
private:
|
||
|
|
typedef typename std::aligned_storage< sizeof( value_type), alignof( value_type) >::type storage_type;
|
||
|
|
|
||
|
|
unbuffered_channel * chan_{ nullptr };
|
||
|
|
storage_type storage_;
|
||
|
|
|
||
|
|
void increment_( bool initial = false) {
|
||
|
|
BOOST_ASSERT( nullptr != chan_);
|
||
|
|
try {
|
||
|
|
if ( ! initial) {
|
||
|
|
reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
|
||
|
|
}
|
||
|
|
::new ( static_cast< void * >( std::addressof( storage_) ) ) value_type{ chan_->value_pop() };
|
||
|
|
} catch ( fiber_error const&) {
|
||
|
|
chan_ = nullptr;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
public:
|
||
|
|
using iterator_category = std::input_iterator_tag;
|
||
|
|
using difference_type = std::ptrdiff_t;
|
||
|
|
using pointer = value_type *;
|
||
|
|
using reference = value_type &;
|
||
|
|
|
||
|
|
using pointer_t = pointer;
|
||
|
|
using reference_t = reference;
|
||
|
|
|
||
|
|
iterator() = default;
|
||
|
|
|
||
|
|
explicit iterator( unbuffered_channel< T > * chan) noexcept :
|
||
|
|
chan_{ chan } {
|
||
|
|
increment_( true);
|
||
|
|
}
|
||
|
|
|
||
|
|
iterator( iterator const& other) noexcept :
|
||
|
|
chan_{ other.chan_ } {
|
||
|
|
}
|
||
|
|
|
||
|
|
iterator & operator=( iterator const& other) noexcept {
|
||
|
|
if ( this == & other) return * this;
|
||
|
|
chan_ = other.chan_;
|
||
|
|
return * this;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool operator==( iterator const& other) const noexcept {
|
||
|
|
return other.chan_ == chan_;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool operator!=( iterator const& other) const noexcept {
|
||
|
|
return other.chan_ != chan_;
|
||
|
|
}
|
||
|
|
|
||
|
|
iterator & operator++() {
|
||
|
|
reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
|
||
|
|
increment_();
|
||
|
|
return * this;
|
||
|
|
}
|
||
|
|
|
||
|
|
const iterator operator++( int) = delete;
|
||
|
|
|
||
|
|
reference_t operator*() noexcept {
|
||
|
|
return * reinterpret_cast< value_type * >( std::addressof( storage_) );
|
||
|
|
}
|
||
|
|
|
||
|
|
pointer_t operator->() noexcept {
|
||
|
|
return reinterpret_cast< value_type * >( std::addressof( storage_) );
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
friend class iterator;
|
||
|
|
};
|
||
|
|
|
||
|
|
template< typename T >
|
||
|
|
typename unbuffered_channel< T >::iterator
|
||
|
|
begin( unbuffered_channel< T > & chan) {
|
||
|
|
return typename unbuffered_channel< T >::iterator( & chan);
|
||
|
|
}
|
||
|
|
|
||
|
|
template< typename T >
|
||
|
|
typename unbuffered_channel< T >::iterator
|
||
|
|
end( unbuffered_channel< T > &) {
|
||
|
|
return typename unbuffered_channel< T >::iterator();
|
||
|
|
}
|
||
|
|
|
||
|
|
}}
|
||
|
|
|
||
|
|
#ifdef BOOST_HAS_ABI_HEADERS
|
||
|
|
# include BOOST_ABI_SUFFIX
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif // BOOST_FIBERS_UNBUFFERED_CHANNEL_H
|