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Copy pathio_service.hpp
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316 lines (245 loc) · 8.51 KB
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///////////////////////////////////////////////////////////////////////////////
// Copyright (c) Lewis Baker
// Licenced under MIT license. See LICENSE.txt for details.
///////////////////////////////////////////////////////////////////////////////
#ifndef CPPCORO_IO_SERVICE_HPP_INCLUDED
#define CPPCORO_IO_SERVICE_HPP_INCLUDED
#include <cppcoro/config.hpp>
#include <cppcoro/cancellation_token.hpp>
#include <cppcoro/cancellation_registration.hpp>
#if CPPCORO_OS_WINNT
# include <cppcoro/detail/win32.hpp>
#endif
#include <optional>
#include <chrono>
#include <cstdint>
#include <atomic>
#include <utility>
#include <experimental/coroutine>
namespace cppcoro
{
class io_service
{
public:
class schedule_operation;
class timed_schedule_operation;
/// Initialises the io_service.
///
/// Does not set a concurrency hint. All threads that enter the
/// event loop will actively process events.
io_service();
/// Initialise the io_service with a concurrency hint.
///
/// \param concurrencyHint
/// Specifies the target maximum number of I/O threads to be
/// actively processing events.
/// Note that the number of active threads may temporarily go
/// above this number.
io_service(std::uint32_t concurrencyHint);
~io_service();
io_service(io_service&& other) = delete;
io_service(const io_service& other) = delete;
io_service& operator=(io_service&& other) = delete;
io_service& operator=(const io_service& other) = delete;
/// Returns an operation that when awaited suspends the awaiting
/// coroutine and reschedules it for resumption on an I/O thread
/// associated with this io_service.
[[nodiscard]]
schedule_operation schedule() noexcept;
/// Returns an operation that when awaited will suspend the
/// awaiting coroutine for the specified delay. Once the delay
/// has elapsed, the coroutine will resume execution on an
/// I/O thread associated with this io_service.
///
/// \param delay
/// The amount of time to delay scheduling resumption of the coroutine
/// on an I/O thread. There is no guarantee that the coroutine will
/// be resumed exactly after this delay.
///
/// \param cancellationToken [optional]
/// A cancellation token that can be used to communicate a request to
/// cancel the delayed schedule operation and schedule it for resumption
/// immediately.
/// The co_await operation will throw cppcoro::operation_cancelled if
/// cancellation was requested before the coroutine could be resumed.
template<typename REP, typename PERIOD>
[[nodiscard]]
timed_schedule_operation schedule_after(
const std::chrono::duration<REP, PERIOD>& delay,
cancellation_token cancellationToken = {}) noexcept;
/// Process events until the io_service is stopped.
///
/// \return
/// The number of events processed during this call.
std::uint64_t process_events();
/// Process events until either the io_service is stopped or
/// there are no more pending events in the queue.
///
/// \return
/// The number of events processed during this call.
std::uint64_t process_pending_events();
/// Block until either one event is processed or the io_service is stopped.
///
/// \return
/// The number of events processed during this call.
/// This will either be 0 or 1.
std::uint64_t process_one_event();
/// Process one event if there are any events pending, otherwise if there
/// are no events pending or the io_service is stopped then return immediately.
///
/// \return
/// The number of events processed during this call.
/// This will either be 0 or 1.
std::uint64_t process_one_pending_event();
/// Shut down the io_service.
///
/// This will cause any threads currently in a call to one of the process_xxx() methods
/// to return from that call once they finish processing the current event.
///
/// This call does not wait until all threads have exited the event loop so you
/// must use other synchronisation mechanisms to wait for those threads.
void stop() noexcept;
/// Reset an io_service to prepare it for resuming processing of events.
///
/// Call this after a call to stop() to allow calls to process_xxx() methods
/// to process events.
///
/// After calling stop() you must ensure that all threads have returned from
/// calls to process_xxx() methods before calling reset().
void reset();
bool is_stop_requested() const noexcept;
void notify_work_started() noexcept;
void notify_work_finished() noexcept;
#if CPPCORO_OS_WINNT
detail::win32::handle_t native_iocp_handle() noexcept;
#endif
private:
class timer_thread_state;
class timer_queue;
friend class schedule_operation;
friend class timed_schedule_operation;
void schedule_impl(schedule_operation* operation) noexcept;
void try_reschedule_overflow_operations() noexcept;
bool try_enter_event_loop() noexcept;
void exit_event_loop() noexcept;
bool try_process_one_event(bool waitForEvent);
void post_wake_up_event() noexcept;
timer_thread_state* ensure_timer_thread_started();
static constexpr std::uint32_t stop_requested_flag = 1;
static constexpr std::uint32_t active_thread_count_increment = 2;
// Bit 0: stop_requested_flag
// Bit 1-31: count of active threads currently running the event loop
std::atomic<std::uint32_t> m_threadState;
std::atomic<std::uint32_t> m_workCount;
#if CPPCORO_OS_WINNT
detail::win32::safe_handle m_iocpHandle;
#endif
// Head of a linked-list of schedule operations that are
// ready to run but that failed to be queued to the I/O
// completion port (eg. due to low memory).
std::atomic<schedule_operation*> m_scheduleOperations;
std::atomic<timer_thread_state*> m_timerState;
};
class io_service::schedule_operation
{
public:
schedule_operation(io_service& service) noexcept
: m_service(service)
{}
bool await_ready() const noexcept { return false; }
void await_suspend(std::experimental::coroutine_handle<> awaiter) noexcept;
void await_resume() const noexcept {}
private:
friend class io_service;
friend class io_service::timed_schedule_operation;
io_service& m_service;
std::experimental::coroutine_handle<> m_awaiter;
schedule_operation* m_next;
};
class io_service::timed_schedule_operation
{
public:
timed_schedule_operation(
io_service& service,
std::chrono::high_resolution_clock::time_point resumeTime,
cppcoro::cancellation_token cancellationToken) noexcept;
timed_schedule_operation(timed_schedule_operation&& other) noexcept;
~timed_schedule_operation();
timed_schedule_operation& operator=(timed_schedule_operation&& other) = delete;
timed_schedule_operation(const timed_schedule_operation& other) = delete;
timed_schedule_operation& operator=(const timed_schedule_operation& other) = delete;
bool await_ready() const noexcept;
void await_suspend(std::experimental::coroutine_handle<> awaiter);
void await_resume();
private:
friend class io_service::timer_queue;
friend class io_service::timer_thread_state;
io_service::schedule_operation m_scheduleOperation;
std::chrono::high_resolution_clock::time_point m_resumeTime;
cppcoro::cancellation_token m_cancellationToken;
std::optional<cppcoro::cancellation_registration> m_cancellationRegistration;
timed_schedule_operation* m_next;
std::atomic<std::uint32_t> m_refCount;
};
class io_work_scope
{
public:
explicit io_work_scope(io_service& service) noexcept
: m_service(&service)
{
service.notify_work_started();
}
io_work_scope(const io_work_scope& other) noexcept
: m_service(other.m_service)
{
if (m_service != nullptr)
{
m_service->notify_work_started();
}
}
io_work_scope(io_work_scope&& other) noexcept
: m_service(other.m_service)
{
other.m_service = nullptr;
}
~io_work_scope()
{
if (m_service != nullptr)
{
m_service->notify_work_finished();
}
}
void swap(io_work_scope& other) noexcept
{
std::swap(m_service, other.m_service);
}
io_work_scope& operator=(io_work_scope other) noexcept
{
swap(other);
return *this;
}
io_service& service() noexcept
{
return *m_service;
}
private:
io_service* m_service;
};
inline void swap(io_work_scope& a, io_work_scope& b)
{
a.swap(b);
}
}
template<typename REP, typename RATIO>
cppcoro::io_service::timed_schedule_operation
cppcoro::io_service::schedule_after(
const std::chrono::duration<REP, RATIO>& duration,
cppcoro::cancellation_token cancellationToken) noexcept
{
return timed_schedule_operation{
*this,
std::chrono::high_resolution_clock::now() + duration,
std::move(cancellationToken)
};
}
#endif
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