21315795177

Committed 24 Jan 2026 01:23PM UTC coverage: 86.888%. First build

Build # 21315795177

Build Type

Pull #435

github

Committed by

web-flow

Commit Message

Merge b39d95fbe into 44d12235a

Pull Request Pull Request #435: Rename io_scheduler to scheduler

Run Details

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87.3

/src/scheduler.cpp

#include "coro/scheduler.hpp"
#include "coro/detail/task_self_deleting.hpp"

#include <atomic>
#include <cstring>
#include <iostream>
#include <optional>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

using namespace std::chrono_literals;

namespace coro
{

namespace detail
{
static auto
    make_spawned_joinable_wait_task(std::unique_ptr<coro::task_group<coro::scheduler>> group_ptr) -> coro::task<void>
{
    co_await *group_ptr;
    co_return;
}

} // namespace detail

scheduler::scheduler(options&& opts, private_constructor)
    : m_opts(opts),
      m_io_notifier(),
      m_timer(static_cast<const void*>(&m_timer_object), m_io_notifier)
{
    if (!m_io_notifier.watch(m_shutdown_pipe.read_fd(), coro::poll_op::read, const_cast<void*>(m_shutdown_ptr), true))
    {
        throw std::runtime_error("Failed to register m_shutdown_pipe.read_fd() for read events.");
    }

    if (!m_io_notifier.watch(m_schedule_pipe.read_fd(), coro::poll_op::read, const_cast<void*>(m_schedule_ptr), true))
    {
        throw std::runtime_error("Failed to register m_schedule.pipe.read_rd() for read events.");
    }

    m_recent_events.reserve(m_max_events);

    if (m_opts.execution_strategy == execution_strategy_t::process_tasks_on_thread_pool)
    {
        m_thread_pool = thread_pool::make_unique(std::move(m_opts.pool));
    }
}

auto scheduler::make_unique(options opts) -> std::unique_ptr<scheduler>
{
    auto s = std::make_unique<scheduler>(std::move(opts), private_constructor{});

    // Spawn the dedicated event loop thread once the scheduler is fully constructed
    // so it has a full object to work with.
    if (s->m_opts.thread_strategy == thread_strategy_t::spawn)
    {
        s->m_io_thread = std::thread([s = s.get()]() { s->process_events_dedicated_thread(); });
    }
    // else manual mode, the user must call process_events.

    return s;
}

scheduler::~scheduler()
{
    shutdown();

    if (m_io_thread.joinable())
    {
        m_io_thread.join();
    }

    m_shutdown_pipe.close();
    m_schedule_pipe.close();
}

auto scheduler::process_events(std::chrono::milliseconds timeout) -> std::size_t
{
    process_events_manual(timeout);
    return size();
}

auto scheduler::spawn_detached(coro::task<void>&& task) -> bool
{
    m_size.fetch_add(1, std::memory_order::release);
    auto wrapper_task = detail::make_task_self_deleting(std::move(task));
    wrapper_task.promise().user_final_suspend([this]() -> void { m_size.fetch_sub(1, std::memory_order::release); });
    return resume(wrapper_task.handle());
}

auto scheduler::spawn_joinable(coro::task<void>&& task) -> coro::task<void>
{
    auto group_ptr = std::make_unique<coro::task_group<coro::scheduler>>(this, std::move(task));
    return detail::make_spawned_joinable_wait_task(std::move(group_ptr));
}

auto scheduler::schedule_at(time_point time) -> coro::task<void>
{
    return yield_until(time);
}

auto scheduler::yield_until(time_point time) -> coro::task<void>
{
    auto now = clock::now();

    // If the requested time is in the past (or now!) bail out!
    if (time <= now)
    {
        co_await schedule();
    }
    else
    {
        m_size.fetch_add(1, std::memory_order::release);

        auto amount = std::chrono::duration_cast<std::chrono::milliseconds>(time - now);

        detail::poll_info pi{};
        add_timer_token(now + amount, pi);
        co_await pi;

        m_size.fetch_sub(1, std::memory_order::release);
    }
    co_return;
}

auto scheduler::poll(
    fd_t fd, coro::poll_op op, std::chrono::milliseconds timeout, std::optional<poll_stop_token> cancel_trigger)
    -> coro::task<poll_status>
{
    // Because the size will drop when this coroutine suspends every poll needs to undo the subtraction
    // on the number of active tasks in the scheduler.  When this task is resumed by the event loop.
    m_size.fetch_add(1, std::memory_order::release);

    // Setup two events, a timeout event and the actual poll for op event.
    // Whichever triggers first will delete the other to guarantee only one wins.
    // The resume token will be set by the scheduler to what the event turned out to be.

    bool timeout_requested = (timeout > 0ms);

    auto pi = detail::poll_info{fd, op, cancel_trigger};

    if (timeout_requested)
    {
        pi.m_timer_pos = add_timer_token(clock::now() + timeout, pi);
    }

    if (!m_io_notifier.watch(pi))
    {
        std::cerr << "Failed to add " << fd << " to watch list\n";
    }

    // The event loop will 'clean-up' whichever event didn't win since the coroutine is scheduled
    // onto the thread poll its possible the other type of event could trigger while its waiting
    // to execute again, thus restarting the coroutine twice, that would be quite bad.
    auto result = co_await pi;
    m_size.fetch_sub(1, std::memory_order::release);
    co_return result;
}

auto scheduler::resume(std::coroutine_handle<> handle) -> bool
{
    if (handle == nullptr || handle.done())
    {
        return false;
    }

    if (m_shutdown_requested.load(std::memory_order::acquire))
    {
        return false;
    }

    if (m_opts.execution_strategy == execution_strategy_t::process_tasks_inline)
    {
        m_size.fetch_add(1, std::memory_order::release);
        {
            std::scoped_lock lk{m_scheduled_tasks_mutex};
            m_scheduled_tasks.emplace_back(handle);
        }

        bool expected{false};
        if (m_schedule_pipe_triggered.compare_exchange_strong(
                expected, true, std::memory_order::release, std::memory_order::relaxed))
        {
            const int value = 1;
            ssize_t written = ::write(m_schedule_pipe.write_fd(), reinterpret_cast<const void*>(&value), sizeof(value));
            if (written != sizeof(value))
            {
                std::cerr << "libcoro::scheduler::resume() failed to write to schedule pipe, bytes written=" << written << "\n";
            }
        }

        return true;
    }
    else
    {
        return m_thread_pool->resume(handle);
    }
}

auto scheduler::shutdown() noexcept -> void
{
    // Only allow shutdown to occur once.
    if (m_shutdown_requested.exchange(true, std::memory_order::acq_rel) == false)
    {
        // Signal the event loop to stop asap.
        const int value{1};
        ssize_t written = ::write(m_shutdown_pipe.write_fd(), reinterpret_cast<const void*>(&value), sizeof(value));
        if (written != sizeof(value))
        {
            std::cerr << "libcoro::scheduler::shutdown() failed to write to shutdown pipe, bytes written=" << written << "\n";
        }

        if (m_io_thread.joinable())
        {
            m_io_thread.join();
        }

        if (m_thread_pool != nullptr)
        {
            m_thread_pool->shutdown();
        }
    }
}

auto scheduler::yield_for_internal(std::chrono::nanoseconds amount) -> coro::task<void>
{
    if (amount <= 0ms)
    {
        co_await schedule();
    }
    else
    {
        // Yield/timeout tasks are considered live in the scheduler and must be accounted for. Note
        // that if the user gives an invalid amount and schedule() is directly called it will account
        // for the scheduled task there.
        m_size.fetch_add(1, std::memory_order::release);

        // Yielding does not require setting the timer position on the poll info since
        // it doesn't have a corresponding 'event' that can trigger, it always waits for
        // the timeout to occur before resuming.

        detail::poll_info pi{};
        add_timer_token(clock::now() + amount, pi);
        co_await pi;

        m_size.fetch_sub(1, std::memory_order::release);
    }
    co_return;
}

auto scheduler::process_events_manual(std::chrono::milliseconds timeout) -> void
{
    bool expected{false};
    if (m_io_processing.compare_exchange_strong(expected, true, std::memory_order::release, std::memory_order::relaxed))
    {
        process_events_execute(timeout);
        m_io_processing.exchange(false, std::memory_order::release);
    }
}

auto scheduler::process_events_dedicated_thread() -> void
{
    if (m_opts.on_io_thread_start_functor != nullptr)
    {
        m_opts.on_io_thread_start_functor();
    }

    m_io_processing.exchange(true, std::memory_order::release);
    // Execute tasks until stopped or there are no more tasks to complete.
    while (!m_shutdown_requested.load(std::memory_order::acquire) || size() > 0)
    {
        process_events_execute(m_default_timeout);
    }
    m_io_processing.exchange(false, std::memory_order::release);

    if (m_opts.on_io_thread_stop_functor != nullptr)
    {
        m_opts.on_io_thread_stop_functor();
    }
}

auto scheduler::process_events_execute(std::chrono::milliseconds timeout) -> void
{
    // Clear the recent events without decreasing the allocated capacity to reduce allocations
    m_recent_events.clear();
    m_io_notifier.next_events(m_recent_events, timeout);

    for (auto& [handle_ptr, poll_status] : m_recent_events)
    {
        if (handle_ptr == m_timer_ptr)
        {
            // Process all events that have timed out.
            process_timeout_execute();
        }
        else if (handle_ptr == m_schedule_ptr)
        {
            // Process scheduled coroutines.
            process_scheduled_execute_inline();
        }
        else if (handle_ptr == m_shutdown_ptr) [[unlikely]]
        {
            // Nothing to do, just needed to wake-up and smell the flowers
        }
        else
        {
            // Individual poll task wake-up.
            process_event_execute(static_cast<detail::poll_info*>(handle_ptr), poll_status);
        }
    }

    // Its important to not resume any handles until the full set is accounted for.  If a timeout
    // and an event for the same handle happen in the same epoll_wait() call then inline processing
    // will destruct the poll_info object before the second event is handled.  This is also possible
    // with thread pool processing, but probably has an extremely low chance of occuring due to
    // the thread switch required.  If m_max_events == 1 this would be unnecessary.

    if (!m_handles_to_resume.empty())
    {
        if (m_opts.execution_strategy == execution_strategy_t::process_tasks_inline)
        {
            for (auto& handle : m_handles_to_resume)
            {
                handle.resume();
            }
        }
        else
        {
            m_thread_pool->resume(m_handles_to_resume);
        }

        m_handles_to_resume.clear();
    }
}

auto scheduler::process_scheduled_execute_inline() -> void
{
    std::vector<std::coroutine_handle<>> tasks{};
    {
        // Acquire the entire list, and then reset it.
        std::scoped_lock lk{m_scheduled_tasks_mutex};
        tasks.swap(m_scheduled_tasks);

        // Clear the notification by reading until the pipe is cleared.
        while (true)
        {
            constexpr std::size_t       READ_COUNT{4};
            constexpr ssize_t           READ_COUNT_BYTES = READ_COUNT * sizeof(int);
            std::array<int, READ_COUNT> control{};
            const ssize_t               result =
                ::read(m_schedule_pipe.read_fd(), reinterpret_cast<void*>(control.data()), READ_COUNT_BYTES);
            if (result == READ_COUNT_BYTES)
            {
                continue;
            }

            // If we got nothing, or we got a partial read break the loop since the pipe is empty.
            if (result >= 0)
            {
                break;
            }

            // pipe is set to O_NONBLOCK so ignore empty blocking reads.
            if (errno == EAGAIN)
            {
                break;
            }

            // Not much we can do here, we're in a very bad state, lets report to stderr.
            std::cerr << "::read(m_schedule_pipe.read_fd()) error[" << errno << "] " << ::strerror(errno) << " fd=["
                      << m_schedule_pipe.read_fd() << "]" << std::endl;
            break;
        }

        // Clear the in memory flag to reduce eventfd_* calls on scheduling.
        m_schedule_pipe_triggered.exchange(false, std::memory_order::release);
    }

    // This set of handles can be safely resumed now since they do not have a corresponding timeout event.
    for (auto& task : tasks)
    {
        task.resume();
    }
    m_size.fetch_sub(tasks.size(), std::memory_order::release);
}

auto scheduler::process_event_execute(detail::poll_info* pi, poll_status status) -> void
{
    if (!pi->m_processed)
    {
        std::atomic_thread_fence(std::memory_order::acquire);
        // Its possible the event and the timeout occurred in the same epoll, make sure only one
        // is ever processed, the other is discarded.
        pi->m_processed = true;

        // Given a valid fd always remove it from epoll so the next poll can blindly EPOLL_CTL_ADD.
        if (pi->m_fd != -1)
        {
            m_io_notifier.unwatch(*pi);
        }

        // Since this event triggered, remove its corresponding timeout if it has one.
        if (pi->m_timer_pos.has_value())
        {
            remove_timer_token(pi->m_timer_pos.value());
        }

        pi->m_poll_status = status;

        while (pi->m_awaiting_coroutine == nullptr)
        {
            std::atomic_thread_fence(std::memory_order::acquire);
        }

        m_handles_to_resume.emplace_back(pi->m_awaiting_coroutine);
    }
}

auto scheduler::process_timeout_execute() -> void
{
    std::vector<detail::poll_info*> poll_infos{};
    auto                            now = clock::now();

    {
        std::scoped_lock lk{m_timed_events_mutex};
        while (!m_timed_events.empty())
        {
            auto first    = m_timed_events.begin();
            auto [tp, pi] = *first;

            if (tp <= now)
            {
                m_timed_events.erase(first);
                poll_infos.emplace_back(pi);
            }
            else
            {
                break;
            }
        }
    }

    for (auto pi : poll_infos)
    {
        if (!pi->m_processed)
        {
            // Its possible the event and the timeout occurred in the same epoll, make sure only one
            // is ever processed, the other is discarded.
            pi->m_processed = true;

            // Since this timed out, remove its corresponding event if it has one.
            if (pi->m_fd != -1)
            {
                m_io_notifier.unwatch(*pi);
            }

            while (pi->m_awaiting_coroutine == nullptr)
            {
                std::atomic_thread_fence(std::memory_order::acquire);
            }

            m_handles_to_resume.emplace_back(pi->m_awaiting_coroutine);
            pi->m_poll_status = coro::poll_status::timeout;
        }
    }

    // Update the time to the next smallest time point, re-take the current now time
    // since updating and resuming tasks could shift the time.
    update_timeout(clock::now());
}

auto scheduler::add_timer_token(time_point tp, detail::poll_info& pi) -> timed_events::iterator
{
    std::scoped_lock lk{m_timed_events_mutex};
    auto             pos = m_timed_events.emplace(tp, &pi);

    // If this item was inserted as the smallest time point, update the timeout.
    if (pos == m_timed_events.begin())
    {
        update_timeout(clock::now());
    }

    return pos;
}

auto scheduler::remove_timer_token(timed_events::iterator pos) -> void
{
    {
        std::scoped_lock lk{m_timed_events_mutex};
        auto             is_first = (m_timed_events.begin() == pos);

        m_timed_events.erase(pos);

        // If this was the first item, update the timeout.  It would be acceptable to just let it
        // also fire the timeout as the event loop will ignore it since nothing will have timed
        // out but it feels like the right thing to do to update it to the correct timeout value.
        if (is_first)
        {
            update_timeout(clock::now());
        }
    }
}

auto scheduler::update_timeout(time_point now) -> void
{
    if (!m_timed_events.empty())
    {
        auto& [tp, pi] = *m_timed_events.begin();

        auto amount = tp - now;

        if (!m_io_notifier.watch_timer(m_timer, amount))
        {
            std::cerr << "Failed to set timerfd errorno=[" << std::string{strerror(errno)} << "].";
        }
    }
    else
    {
        m_io_notifier.unwatch_timer(m_timer);
    }
}

} // namespace coro

1	#include "coro/scheduler.hpp"
2	#include "coro/detail/task_self_deleting.hpp"
3
4	#include <atomic>
5	#include <cstring>
6	#include <iostream>
7	#include <optional>
8	#include <sys/socket.h>
9	#include <sys/types.h>
10	#include <unistd.h>
11
12	using namespace std::chrono_literals;
13
14	namespace coro
15	{
16
17	namespace detail
18	{
19	static auto
NEW 20	make_spawned_joinable_wait_task(std::unique_ptr<coro::task_group<coro::scheduler>> group_ptr) -> coro::task<void>	×
21	{
22	co_await *group_ptr;
23	co_return;
24	}	×
25
26	} // namespace detail
27
28	scheduler::scheduler(options&& opts, private_constructor)	89✔
29	: m_opts(opts),	89✔
30	m_io_notifier(),	89✔
31	m_timer(static_cast<const void*>(&m_timer_object), m_io_notifier)	178✔
32	{
33	if (!m_io_notifier.watch(m_shutdown_pipe.read_fd(), coro::poll_op::read, const_cast<void*>(m_shutdown_ptr), true))	89✔
34	{
35	throw std::runtime_error("Failed to register m_shutdown_pipe.read_fd() for read events.");	×
36	}
37
38	if (!m_io_notifier.watch(m_schedule_pipe.read_fd(), coro::poll_op::read, const_cast<void*>(m_schedule_ptr), true))	89✔
39	{
40	throw std::runtime_error("Failed to register m_schedule.pipe.read_rd() for read events.");	×
41	}
42
43	m_recent_events.reserve(m_max_events);	89✔
44
45	if (m_opts.execution_strategy == execution_strategy_t::process_tasks_on_thread_pool)	89✔
46	{
47	m_thread_pool = thread_pool::make_unique(std::move(m_opts.pool));	46✔
48	}
49	}	89✔
50
51	auto scheduler::make_unique(options opts) -> std::unique_ptr<scheduler>	89✔
52	{
53	auto s = std::make_unique<scheduler>(std::move(opts), private_constructor{});	89✔
54
55	// Spawn the dedicated event loop thread once the scheduler is fully constructed
56	// so it has a full object to work with.
57	if (s->m_opts.thread_strategy == thread_strategy_t::spawn)	89✔
58	{
59	s->m_io_thread = std::thread([s = s.get()]() { s->process_events_dedicated_thread(); });	174✔
60	}
61	// else manual mode, the user must call process_events.
62
63	return s;	89✔
64	}	×
65
66	scheduler::~scheduler()	178✔
67	{
68	shutdown();	89✔
69
70	if (m_io_thread.joinable())	89✔
71	{
72	m_io_thread.join();	×
73	}
74
75	m_shutdown_pipe.close();	89✔
76	m_schedule_pipe.close();	89✔
77	}	178✔
78
79	auto scheduler::process_events(std::chrono::milliseconds timeout) -> std::size_t	4✔
80	{
81	process_events_manual(timeout);	4✔
82	return size();	4✔
83	}
84
85	auto scheduler::spawn_detached(coro::task<void>&& task) -> bool	200,319✔
86	{
87	m_size.fetch_add(1, std::memory_order::release);	200,319✔
88	auto wrapper_task = detail::make_task_self_deleting(std::move(task));	200,319✔
89	wrapper_task.promise().user_final_suspend([this]() -> void { m_size.fetch_sub(1, std::memory_order::release); });	400,636✔
90	return resume(wrapper_task.handle());	200,319✔
91	}
92
NEW 93	auto scheduler::spawn_joinable(coro::task<void>&& task) -> coro::task<void>	×
94	{
NEW 95	auto group_ptr = std::make_unique<coro::task_group<coro::scheduler>>(this, std::move(task));	×
96	return detail::make_spawned_joinable_wait_task(std::move(group_ptr));	×
97	}	×
98
99	auto scheduler::schedule_at(time_point time) -> coro::task<void>	3✔
100	{
101	return yield_until(time);	3✔
102	}
103
104	auto scheduler::yield_until(time_point time) -> coro::task<void>	4✔
105	{
106	auto now = clock::now();
107
108	// If the requested time is in the past (or now!) bail out!
109	if (time <= now)
110	{
111	co_await schedule();
112	}
113	else
114	{
115	m_size.fetch_add(1, std::memory_order::release);
116
117	auto amount = std::chrono::duration_cast<std::chrono::milliseconds>(time - now);
118
119	detail::poll_info pi{};
120	add_timer_token(now + amount, pi);
121	co_await pi;
122
123	m_size.fetch_sub(1, std::memory_order::release);
124	}
125	co_return;
126	}	8✔
127
128	auto scheduler::poll(	600,062✔
129	fd_t fd, coro::poll_op op, std::chrono::milliseconds timeout, std::optional<poll_stop_token> cancel_trigger)
130	-> coro::task<poll_status>
131	{
132	// Because the size will drop when this coroutine suspends every poll needs to undo the subtraction
133	// on the number of active tasks in the scheduler. When this task is resumed by the event loop.
134	m_size.fetch_add(1, std::memory_order::release);
135
136	// Setup two events, a timeout event and the actual poll for op event.
137	// Whichever triggers first will delete the other to guarantee only one wins.
138	// The resume token will be set by the scheduler to what the event turned out to be.
139
140	bool timeout_requested = (timeout > 0ms);
141
142	auto pi = detail::poll_info{fd, op, cancel_trigger};
143
144	if (timeout_requested)
145	{
146	pi.m_timer_pos = add_timer_token(clock::now() + timeout, pi);
147	}
148
149	if (!m_io_notifier.watch(pi))
150	{
151	std::cerr << "Failed to add " << fd << " to watch list\n";
152	}
153
154	// The event loop will 'clean-up' whichever event didn't win since the coroutine is scheduled
155	// onto the thread poll its possible the other type of event could trigger while its waiting
156	// to execute again, thus restarting the coroutine twice, that would be quite bad.
157	auto result = co_await pi;
158	m_size.fetch_sub(1, std::memory_order::release);
159	co_return result;
160	}	1,199,383✔
161
162	auto scheduler::resume(std::coroutine_handle<> handle) -> bool	200,379✔
163	{
164	if (handle == nullptr \|\| handle.done())	200,379✔
165	{
166	return false;	×
167	}
168
169	if (m_shutdown_requested.load(std::memory_order::acquire))	200,379✔
170	{
171	return false;	×
172	}
173
174	if (m_opts.execution_strategy == execution_strategy_t::process_tasks_inline)	200,379✔
175	{
176	m_size.fetch_add(1, std::memory_order::release);	102✔
177	{
178	std::scoped_lock lk{m_scheduled_tasks_mutex};	102✔
179	m_scheduled_tasks.emplace_back(handle);	102✔
180	}	102✔
181
182	bool expected{false};	102✔
183	if (m_schedule_pipe_triggered.compare_exchange_strong(	102✔
184	expected, true, std::memory_order::release, std::memory_order::relaxed))
185	{
186	const int value = 1;	102✔
187	ssize_t written = ::write(m_schedule_pipe.write_fd(), reinterpret_cast<const void*>(&value), sizeof(value));	102✔
188	if (written != sizeof(value))	102✔
189	{
NEW 190	std::cerr << "libcoro::scheduler::resume() failed to write to schedule pipe, bytes written=" << written << "\n";	×
191	}
192	}
193
194	return true;	102✔
195	}
196	else
197	{
198	return m_thread_pool->resume(handle);	200,277✔
199	}
200	}
201
202	auto scheduler::shutdown() noexcept -> void	133✔
203	{
204	// Only allow shutdown to occur once.
205	if (m_shutdown_requested.exchange(true, std::memory_order::acq_rel) == false)	133✔
206	{
207	// Signal the event loop to stop asap.
208	const int value{1};	89✔
209	ssize_t written = ::write(m_shutdown_pipe.write_fd(), reinterpret_cast<const void*>(&value), sizeof(value));	89✔
210	if (written != sizeof(value))	89✔
211	{
NEW 212	std::cerr << "libcoro::scheduler::shutdown() failed to write to shutdown pipe, bytes written=" << written << "\n";	×
213	}
214
215	if (m_io_thread.joinable())	89✔
216	{
217	m_io_thread.join();	87✔
218	}
219
220	if (m_thread_pool != nullptr)	89✔
221	{
222	m_thread_pool->shutdown();	46✔
223	}
224	}
225	}	133✔
226
227	auto scheduler::yield_for_internal(std::chrono::nanoseconds amount) -> coro::task<void>	5,000,170✔
228	{
229	if (amount <= 0ms)
230	{
231	co_await schedule();
232	}
233	else
234	{
235	// Yield/timeout tasks are considered live in the scheduler and must be accounted for. Note
236	// that if the user gives an invalid amount and schedule() is directly called it will account
237	// for the scheduled task there.
238	m_size.fetch_add(1, std::memory_order::release);
239
240	// Yielding does not require setting the timer position on the poll info since
241	// it doesn't have a corresponding 'event' that can trigger, it always waits for
242	// the timeout to occur before resuming.
243
244	detail::poll_info pi{};
245	add_timer_token(clock::now() + amount, pi);
246	co_await pi;
247
248	m_size.fetch_sub(1, std::memory_order::release);
249	}
250	co_return;
251	}	10,000,340✔
252
253	auto scheduler::process_events_manual(std::chrono::milliseconds timeout) -> void	4✔
254	{
255	bool expected{false};	4✔
256	if (m_io_processing.compare_exchange_strong(expected, true, std::memory_order::release, std::memory_order::relaxed))	4✔
257	{
258	process_events_execute(timeout);	4✔
259	m_io_processing.exchange(false, std::memory_order::release);	4✔
260	}
261	}	4✔
262
263	auto scheduler::process_events_dedicated_thread() -> void	87✔
264	{
265	if (m_opts.on_io_thread_start_functor != nullptr)	87✔
266	{
267	m_opts.on_io_thread_start_functor();	×
268	}
269
270	m_io_processing.exchange(true, std::memory_order::release);	87✔
271	// Execute tasks until stopped or there are no more tasks to complete.
272	while (!m_shutdown_requested.load(std::memory_order::acquire) \|\| size() > 0)	979,454✔
273	{
274	process_events_execute(m_default_timeout);	979,358✔
275	}
276	m_io_processing.exchange(false, std::memory_order::release);	81✔
277
278	if (m_opts.on_io_thread_stop_functor != nullptr)	87✔
279	{
280	m_opts.on_io_thread_stop_functor();	×
281	}
282	}	87✔
283
284	auto scheduler::process_events_execute(std::chrono::milliseconds timeout) -> void	979,352✔
285	{
286	// Clear the recent events without decreasing the allocated capacity to reduce allocations
287	m_recent_events.clear();	979,352✔
288	m_io_notifier.next_events(m_recent_events, timeout);	979,344✔
289
290	for (auto& [handle_ptr, poll_status] : m_recent_events)	2,415,429✔
291	{
292	if (handle_ptr == m_timer_ptr)	1,436,168✔
293	{
294	// Process all events that have timed out.
295	process_timeout_execute();	834,938✔
296	}
297	else if (handle_ptr == m_schedule_ptr)	601,230✔
298	{
299	// Process scheduled coroutines.
300	process_scheduled_execute_inline();	130✔
301	}
302	else if (handle_ptr == m_shutdown_ptr) [[unlikely]]	601,100✔
303	{
304	// Nothing to do, just needed to wake-up and smell the flowers
305	}
306	else
307	{
308	// Individual poll task wake-up.
309	process_event_execute(static_cast<detail::poll_info*>(handle_ptr), poll_status);	601,015✔
310	}
311	}
312
313	// Its important to not resume any handles until the full set is accounted for. If a timeout
314	// and an event for the same handle happen in the same epoll_wait() call then inline processing
315	// will destruct the poll_info object before the second event is handled. This is also possible
316	// with thread pool processing, but probably has an extremely low chance of occuring due to
317	// the thread switch required. If m_max_events == 1 this would be unnecessary.
318
319	if (!m_handles_to_resume.empty())	979,110✔
320	{
321	if (m_opts.execution_strategy == execution_strategy_t::process_tasks_inline)	979,257✔
322	{
323	for (auto& handle : m_handles_to_resume)	1,019✔
324	{
325	handle.resume();	756✔
326	}
327	}
328	else
329	{
330	m_thread_pool->resume(m_handles_to_resume);	978,997✔
331	}
332
333	m_handles_to_resume.clear();	979,261✔
334	}
335	}	979,348✔
336
337	auto scheduler::process_scheduled_execute_inline() -> void	130✔
338	{
339	std::vector<std::coroutine_handle<>> tasks{};	130✔
340	{
341	// Acquire the entire list, and then reset it.
342	std::scoped_lock lk{m_scheduled_tasks_mutex};	130✔
343	tasks.swap(m_scheduled_tasks);	130✔
344
345	// Clear the notification by reading until the pipe is cleared.
346	while (true)
347	{
348	constexpr std::size_t READ_COUNT{4};	130✔
349	constexpr ssize_t READ_COUNT_BYTES = READ_COUNT * sizeof(int);	130✔
350	std::array<int, READ_COUNT> control{};	130✔
351	const ssize_t result =
352	::read(m_schedule_pipe.read_fd(), reinterpret_cast<void*>(control.data()), READ_COUNT_BYTES);	130✔
353	if (result == READ_COUNT_BYTES)	130✔
354	{
355	continue;	×
356	}
357
358	// If we got nothing, or we got a partial read break the loop since the pipe is empty.
359	if (result >= 0)	130✔
360	{
361	break;	130✔
362	}
363
364	// pipe is set to O_NONBLOCK so ignore empty blocking reads.
365	if (errno == EAGAIN)	×
366	{
367	break;	×
368	}
369
370	// Not much we can do here, we're in a very bad state, lets report to stderr.
371	std::cerr << "::read(m_schedule_pipe.read_fd()) error[" << errno << "] " << ::strerror(errno) << " fd=["	×
372	<< m_schedule_pipe.read_fd() << "]" << std::endl;	×
373	break;	×
374	}	×
375
376	// Clear the in memory flag to reduce eventfd_* calls on scheduling.
377	m_schedule_pipe_triggered.exchange(false, std::memory_order::release);	130✔
378	}	130✔
379
380	// This set of handles can be safely resumed now since they do not have a corresponding timeout event.
381	for (auto& task : tasks)	365✔
382	{
383	task.resume();	237✔
384	}
385	m_size.fetch_sub(tasks.size(), std::memory_order::release);	129✔
386	}	129✔
387
388	auto scheduler::process_event_execute(detail::poll_info* pi, poll_status status) -> void	600,936✔
389	{
390	if (!pi->m_processed)	600,936✔
391	{
392	std::atomic_thread_fence(std::memory_order::acquire);
393	// Its possible the event and the timeout occurred in the same epoll, make sure only one
394	// is ever processed, the other is discarded.
395	pi->m_processed = true;	601,002✔
396
397	// Given a valid fd always remove it from epoll so the next poll can blindly EPOLL_CTL_ADD.
398	if (pi->m_fd != -1)	601,002✔
399	{
400	m_io_notifier.unwatch(*pi);	601,460✔
401	}
402
403	// Since this event triggered, remove its corresponding timeout if it has one.
404	if (pi->m_timer_pos.has_value())	600,886✔
405	{
406	remove_timer_token(pi->m_timer_pos.value());	100,606✔
407	}
408
409	pi->m_poll_status = status;	601,192✔
410
411	while (pi->m_awaiting_coroutine == nullptr)	73,736,686✔
412	{
413	std::atomic_thread_fence(std::memory_order::acquire);
414	}
415
416	m_handles_to_resume.emplace_back(pi->m_awaiting_coroutine);	601,093✔
417	}
418	}	600,698✔
419
420	auto scheduler::process_timeout_execute() -> void	834,938✔
421	{
422	std::vector<detail::poll_info*> poll_infos{};	834,938✔
423	auto now = clock::now();	834,938✔
424
425	{
426	std::scoped_lock lk{m_timed_events_mutex};	834,938✔
427	while (!m_timed_events.empty())	5,835,122✔
428	{
429	auto first = m_timed_events.begin();	5,835,071✔
430	auto [tp, pi] = *first;	5,835,071✔
431
432	if (tp <= now)	5,835,071✔
433	{
434	m_timed_events.erase(first);	5,000,184✔
435	poll_infos.emplace_back(pi);	5,000,184✔
436	}
437	else
438	{
439	break;	834,887✔
440	}
441	}
442	}	834,938✔
443
444	for (auto pi : poll_infos)	5,835,122✔
445	{
446	if (!pi->m_processed)	5,000,184✔
447	{
448	// Its possible the event and the timeout occurred in the same epoll, make sure only one
449	// is ever processed, the other is discarded.
450	pi->m_processed = true;	5,000,184✔
451
452	// Since this timed out, remove its corresponding event if it has one.
453	if (pi->m_fd != -1)	5,000,184✔
454	{
455	m_io_notifier.unwatch(*pi);	13✔
456	}
457
458	while (pi->m_awaiting_coroutine == nullptr)	5,000,184✔
459	{
460	std::atomic_thread_fence(std::memory_order::acquire);
461	}
462
463	m_handles_to_resume.emplace_back(pi->m_awaiting_coroutine);	5,000,184✔
464	pi->m_poll_status = coro::poll_status::timeout;	5,000,184✔
465	}
466	}
467
468	// Update the time to the next smallest time point, re-take the current now time
469	// since updating and resuming tasks could shift the time.
470	update_timeout(clock::now());	834,938✔
471	}	834,938✔
472
473	auto scheduler::add_timer_token(time_point tp, detail::poll_info& pi) -> timed_events::iterator	5,100,540✔
474	{
475	std::scoped_lock lk{m_timed_events_mutex};	5,100,540✔
476	auto pos = m_timed_events.emplace(tp, &pi);	5,100,790✔
477
478	// If this item was inserted as the smallest time point, update the timeout.
479	if (pos == m_timed_events.begin())	5,100,790✔
480	{
481	update_timeout(clock::now());	717✔
482	}
483
484	return pos;	5,100,790✔
485	}	5,100,790✔
486
487	auto scheduler::remove_timer_token(timed_events::iterator pos) -> void	100,606✔
488	{
489	{
490	std::scoped_lock lk{m_timed_events_mutex};	100,606✔
491	auto is_first = (m_timed_events.begin() == pos);	100,606✔
492
493	m_timed_events.erase(pos);	100,605✔
494
495	// If this was the first item, update the timeout. It would be acceptable to just let it
496	// also fire the timeout as the event loop will ignore it since nothing will have timed
497	// out but it feels like the right thing to do to update it to the correct timeout value.
498	if (is_first)	100,607✔
499	{
500	update_timeout(clock::now());	39,157✔
501	}
502	}	100,607✔
503	}	100,607✔
504
505	auto scheduler::update_timeout(time_point now) -> void	874,812✔
506	{
507	if (!m_timed_events.empty())	874,812✔
508	{
509	auto& [tp, pi] = *m_timed_events.begin();	874,235✔
510
511	auto amount = tp - now;	874,235✔
512
513	if (!m_io_notifier.watch_timer(m_timer, amount))	874,234✔
514	{
515	std::cerr << "Failed to set timerfd errorno=[" << std::string{strerror(errno)} << "].";	×
516	}
517	}
518	else
519	{
520	m_io_notifier.unwatch_timer(m_timer);	577✔
521	}
522	}	874,812✔
523
524	} // namespace coro

jbaldwin / libcoro / 21315795177

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