541 lines
20 KiB
C++
541 lines
20 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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#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 unbuffered_channel {
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public:
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typedef T value_type;
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private:
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typedef context::wait_queue_t wait_queue_type;
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struct alignas(cache_alignment) slot {
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value_type value;
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context * ctx;
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slot( value_type const& value_, context * ctx_) :
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value{ value_ },
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ctx{ ctx_ } {
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}
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slot( value_type && value_, context * ctx_) :
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value{ std::move( value_) },
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ctx{ ctx_ } {
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}
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};
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// shared cacheline
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alignas(cache_alignment) std::atomic< slot * > slot_{ nullptr };
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// shared cacheline
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alignas(cache_alignment) std::atomic_bool closed_{ false };
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mutable detail::spinlock splk_{};
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wait_queue_type waiting_producers_{};
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wait_queue_type 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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} else {
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return false;
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}
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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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slot * s{ nullptr };
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if ( nullptr != ( s = try_pop_() ) ) {
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BOOST_ASSERT( nullptr != s);
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BOOST_ASSERT( nullptr != s->ctx);
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// value will be destructed in the context of the waiting fiber
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context::active()->set_ready( s->ctx);
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}
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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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context * ctx{ context::active() };
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detail::spinlock_lock lk{ splk_ };
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closed_.store( true, std::memory_order_release);
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// notify all waiting producers
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while ( ! waiting_producers_.empty() ) {
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context * producer_ctx{ & waiting_producers_.front() };
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waiting_producers_.pop_front();
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ctx->set_ready( producer_ctx);
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}
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// notify all waiting consumers
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while ( ! waiting_consumers_.empty() ) {
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context * consumer_ctx{ & waiting_consumers_.front() };
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waiting_consumers_.pop_front();
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ctx->set_ready( consumer_ctx);
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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 * ctx{ context::active() };
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slot s{ value, ctx };
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for (;;) {
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if ( is_closed() ) {
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return channel_op_status::closed;
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}
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_ };
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// notify one waiting consumer
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if ( ! waiting_consumers_.empty() ) {
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context * consumer_ctx{ & waiting_consumers_.front() };
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waiting_consumers_.pop_front();
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ctx->set_ready( consumer_ctx);
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}
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// suspend till value has been consumed
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ctx->suspend( lk);
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// resumed, value has been consumed
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_producers_);
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// suspend this producer
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ctx->suspend( lk);
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// resumed, slot mabye free
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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 * ctx{ context::active() };
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slot s{ std::move( value), ctx };
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for (;;) {
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if ( is_closed() ) {
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return channel_op_status::closed;
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}
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_ };
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// notify one waiting consumer
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if ( ! waiting_consumers_.empty() ) {
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context * consumer_ctx{ & waiting_consumers_.front() };
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waiting_consumers_.pop_front();
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ctx->set_ready( consumer_ctx);
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}
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// suspend till value has been consumed
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ctx->suspend( lk);
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// resumed, value has been consumed
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_producers_);
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// suspend this producer
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ctx->suspend( lk);
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// resumed, slot mabye free
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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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std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
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context * ctx{ context::active() };
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slot s{ value, ctx };
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for (;;) {
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if ( is_closed() ) {
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return channel_op_status::closed;
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}
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_ };
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// notify one waiting consumer
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if ( ! waiting_consumers_.empty() ) {
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context * consumer_ctx{ & waiting_consumers_.front() };
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waiting_consumers_.pop_front();
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ctx->set_ready( consumer_ctx);
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}
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// suspend this producer
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if ( ! ctx->wait_until( timeout_time, lk) ) {
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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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// relock local lk
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lk.lock();
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// remove from waiting-queue
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ctx->wait_unlink();
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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, value has been consumed
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_producers_);
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// suspend this producer
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if ( ! ctx->wait_until( timeout_time, lk) ) {
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// relock local lk
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lk.lock();
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// remove from waiting-queue
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ctx->wait_unlink();
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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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}
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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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std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
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context * ctx{ context::active() };
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slot s{ std::move( value), ctx };
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for (;;) {
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if ( is_closed() ) {
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return channel_op_status::closed;
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}
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if ( try_push_( & s) ) {
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detail::spinlock_lock lk{ splk_ };
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// notify one waiting consumer
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if ( ! waiting_consumers_.empty() ) {
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context * consumer_ctx{ & waiting_consumers_.front() };
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waiting_consumers_.pop_front();
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ctx->set_ready( consumer_ctx);
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}
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// suspend this producer
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if ( ! ctx->wait_until( timeout_time, lk) ) {
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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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// relock local lk
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lk.lock();
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// remove from waiting-queue
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ctx->wait_unlink();
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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, value has been consumed
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_producers_);
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// suspend this producer
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if ( ! ctx->wait_until( timeout_time, lk) ) {
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// relock local lk
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lk.lock();
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// remove from waiting-queue
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ctx->wait_unlink();
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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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}
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channel_op_status pop( value_type & value) {
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context * 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_ };
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// notify one waiting producer
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if ( ! waiting_producers_.empty() ) {
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context * producer_ctx{ & waiting_producers_.front() };
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waiting_producers_.pop_front();
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lk.unlock();
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ctx->set_ready( producer_ctx);
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}
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}
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// consume value
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value = std::move( s->value);
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// resume suspended producer
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ctx->set_ready( s->ctx);
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_consumers_);
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// suspend this consumer
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ctx->suspend( lk);
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// resumed, slot mabye set
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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 * 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_ };
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// notify one waiting producer
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if ( ! waiting_producers_.empty() ) {
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context * producer_ctx{ & waiting_producers_.front() };
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waiting_producers_.pop_front();
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lk.unlock();
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ctx->set_ready( producer_ctx);
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}
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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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// resume suspended producer
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ctx->set_ready( s->ctx);
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return std::move( value);
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_consumers_);
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// suspend this consumer
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ctx->suspend( lk);
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// resumed, slot mabye set
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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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std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
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context * 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_ };
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// notify one waiting producer
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if ( ! waiting_producers_.empty() ) {
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context * producer_ctx{ & waiting_producers_.front() };
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waiting_producers_.pop_front();
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lk.unlock();
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ctx->set_ready( producer_ctx);
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}
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}
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// consume value
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value = std::move( s->value);
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// resume suspended producer
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ctx->set_ready( s->ctx);
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return channel_op_status::success;
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} else {
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BOOST_ASSERT( ! ctx->wait_is_linked() );
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detail::spinlock_lock lk{ splk_ };
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if ( 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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ctx->wait_link( waiting_consumers_);
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// suspend this consumer
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if ( ! ctx->wait_until( timeout_time, lk) ) {
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// relock local lk
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lk.lock();
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// remove from waiting-queue
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ctx->wait_unlink();
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return channel_op_status::timeout;
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}
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}
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}
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}
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class iterator : public std::iterator< std::input_iterator_tag, typename std::remove_reference< value_type >::type > {
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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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unbuffered_channel * chan_{ nullptr };
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storage_type storage_;
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void increment_() {
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BOOST_ASSERT( nullptr != chan_);
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try {
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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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typedef typename iterator::pointer pointer_t;
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typedef typename iterator::reference reference_t;
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iterator() noexcept = default;
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explicit iterator( unbuffered_channel< T > * chan) noexcept :
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chan_{ chan } {
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increment_();
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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 ( this == & other) return * this;
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chan_ = other.chan_;
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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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increment_();
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return * this;
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}
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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 unbuffered_channel< T >::iterator
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begin( unbuffered_channel< T > & chan) {
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return typename unbuffered_channel< T >::iterator( & chan);
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}
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template< typename T >
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typename unbuffered_channel< T >::iterator
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end( unbuffered_channel< T > &) {
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return typename unbuffered_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_UNBUFFERED_CHANNEL_H
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