NNet::TPollerBase Class Reference

Base class for pollers managing asynchronous I/O events and timers. More...

#include <poller.hpp>

Inheritance diagram for NNet::TPollerBase:

Public Member Functions
	TPollerBase ()=default
	Default constructor.
	TPollerBase (const TPollerBase &)=delete
	Copying is disabled.
TPollerBase &	operator= (const TPollerBase &)=delete
unsigned	AddTimer (TTime deadline, THandle h)
	Schedules a timer.
bool	RemoveTimer (unsigned timerId, TTime deadline)
	Removes or cancels a timer.
void	AddRead (int fd, THandle h)
	Registers a read event on a file descriptor.
void	AddWrite (int fd, THandle h)
	Registers a write event on a file descriptor.
void	AddRemoteHup (int fd, THandle h)
	Registers a remote hang-up (RHUP) event.
void	RemoveEvent (int fd)
	Removes registered events for a specific file descriptor.
void	RemoveEvent (THandle)
	Removes events associated with a given coroutine handle.
auto	Sleep (TTime until)
	Suspends execution until the specified time.
template<typename Rep , typename Period >
auto	Sleep (std::chrono::duration< Rep, Period > duration)
	Overload of Sleep() accepting a duration.
auto	Yield ()
	Yields execution to the next event loop iteration.
void	Wakeup (TEvent &&change)
	Wakes up a coroutine waiting on an event.
void	WakeupReadyHandles ()
	Wakes up all coroutines waiting on ready events.
void	SetMaxDuration (std::chrono::milliseconds maxDuration)
	Sets the maximum polling duration.
auto	TimersSize () const
	Returns the number of scheduled timers.

Protected Member Functions
timespec	GetTimeout () const
	Computes the poll timeout based on scheduled timers.
void	Reset ()
	Clears the lists of ready events and pending changes.
void	ProcessTimers ()
	Processes scheduled timers.

Static Protected Member Functions
static constexpr timespec	GetMaxDuration (std::chrono::milliseconds duration)
	Computes a timespec from a duration.

Protected Attributes
int	MaxFd_ = 0
	Highest file descriptor in use.
std::vector< TEvent >	Changes_
	Pending changes (registered events).
std::vector< TEvent >	ReadyEvents_
	Events ready to wake up their coroutines.
unsigned	TimerId_ = 0
	Counter for generating unique timer IDs.
std::priority_queue< TTimer >	Timers_
	Priority queue for scheduled timers.
TTime	LastTimersProcessTime_
	Last time timers were processed.
unsigned	LastFiredTimer_ = (unsigned)(-1)
	ID of the last fired timer.
std::chrono::milliseconds	MaxDuration_ = std::chrono::milliseconds(100)
	Maximum poll duration.
timespec	MaxDurationTs_ = GetMaxDuration(MaxDuration_)
	Max duration represented as timespec.

Detailed Description

Base class for pollers managing asynchronous I/O events and timers.

TPollerBase provides the common interface and functionality for pollers that drive asynchronous operations. It allows scheduling timers, registering I/O events (read, write, remote hang-up) on file descriptors, and waking up waiting coroutines. It also offers convenience methods such as Sleep() (and its overload accepting a std::chrono::duration) and Yield().

The class maintains internal collections for pending changes (events), ready events, and timers. It also keeps track of the maximum file descriptor, which is used in system-level polling calls.

Key methods include:

• AddTimer() to schedule a timer.
• RemoveTimer() to cancel a timer.
• AddRead(), AddWrite(), AddRemoteHup() to register I/O events.
• RemoveEvent() to deregister events.
• Sleep() and Yield() to suspend execution until a specified time or until the next polling round.
• Wakeup() and WakeupReadyHandles() to resume waiting coroutines when events occur.

The class also provides helper methods for computing timeout values (via GetTimeout()).

The detailed comment inside Wakeup() describes how a waiting coroutine is resumed and how new event registrations are matched.

Member Function Documentation

AddRead()

void NNet::TPollerBase::AddRead ( int  fd, THandle  h  )

inline

Registers a read event on a file descriptor.

Parameters

fd	The file descriptor.
h	The coroutine handle to resume when data is available.

AddRemoteHup()

void NNet::TPollerBase::AddRemoteHup ( int  fd, THandle  h  )

inline

Registers a remote hang-up (RHUP) event.

Parameters

fd	The file descriptor.
h	The coroutine handle to resume when the remote end closes the connection.

AddTimer()

unsigned NNet::TPollerBase::AddTimer ( TTime  deadline, THandle  h  )

inline

Schedules a timer.

Inserts a timer event with the given deadline and coroutine handle into the internal timer queue.

Parameters

deadline	The time at which the timer should fire.
h	The handle of the coroutine to resume when the timer expires.

Returns

A unique timer ID.

AddWrite()

void NNet::TPollerBase::AddWrite ( int  fd, THandle  h  )

inline

Registers a write event on a file descriptor.

Parameters

fd	The file descriptor.
h	The coroutine handle to resume when ready for writing.

GetMaxDuration()

static constexpr timespec NNet::TPollerBase::GetMaxDuration ( std::chrono::milliseconds  duration )

inlinestaticconstexprprotected

Computes a timespec from a duration.

Parameters

duration

The maximum duration in milliseconds.

Returns

A timespec representing the duration.

GetTimeout()

timespec NNet::TPollerBase::GetTimeout ( ) const

inlineprotected

Computes the poll timeout based on scheduled timers.

Returns

A timespec representing the timeout.

ProcessTimers()

void NNet::TPollerBase::ProcessTimers ( )

inlineprotected

Processes scheduled timers.

Resumes waiting coroutines for timers that have expired. The method tracks whether a timer was fired by comparing its ID to LastFiredTimer_.

RemoveEvent() [1/2]

void NNet::TPollerBase::RemoveEvent ( int  fd )

inline

Removes registered events for a specific file descriptor.

This method signals that events for a descriptor should be deregistered.

Parameters

fd	The file descriptor.

RemoveEvent() [2/2]

void NNet::TPollerBase::RemoveEvent ( THandle  )

inline

Removes events associated with a given coroutine handle.

This overload will be called by destructors of unfinished futures. Unimplemented.

Parameters

h	The coroutine handle.

RemoveTimer()

bool NNet::TPollerBase::RemoveTimer ( unsigned  timerId, TTime  deadline  )

inline

Removes or cancels a timer.

Checks if the specified timer (by its ID) has fired based on the deadline; if not, inserts an empty timer to force removal.

Parameters

timerId	The timer ID to remove.
deadline	The associated deadline.

Returns

True if the timer had already fired; false otherwise.

SetMaxDuration()

void NNet::TPollerBase::SetMaxDuration ( std::chrono::milliseconds  maxDuration )

inline

Sets the maximum polling duration.

Parameters

maxDuration

The maximum duration for a poll cycle.

Sleep() [1/2]

template<typename Rep , typename Period >

auto NNet::TPollerBase::Sleep ( std::chrono::duration< Rep, Period >  duration )

inline

Overload of Sleep() accepting a duration.

Template Parameters

Rep	The representation type.
Period	The period type.

Parameters

duration

The duration to sleep.

Returns

An awaitable sleep object.

Sleep() [2/2]

auto NNet::TPollerBase::Sleep ( TTime  until )

inline

Suspends execution until the specified time.

Returns an awaitable object that registers a timer and suspends the current coroutine until the deadline.

Parameters

until

The time until which to sleep.

Returns

An awaitable sleep object.

Wakeup()

void NNet::TPollerBase::Wakeup ( TEvent &&  change )

inline

Wakes up a coroutine waiting on an event.

This method resumes the coroutine associated with the given TEvent (change), then checks whether that coroutine has added a new wait for the same file descriptor.

Parameters

change

The event change containing the file descriptor and coroutine handle.

Wakes up the coroutine associated with the given TEvent change, then checks whether that coroutine has added a new wait on the same file descriptor (Fd). We first store the current size of the Changes_ vector and call change.Handle.resume().

If after resuming, the coroutine does NOT add (or match) a wait entry for change.Fd, we assume that this descriptor is not in use yet and remove it from the poller by resetting change.Handle and appending change to Changes_.

In most cases, Changes_ grows by exactly one entry after resuming a coroutine (it suspends again on a descriptor), but there are scenarios where it can grow by more than one. For example, one coroutine might launch another coroutine without waiting; that second coroutine suspends on ReadSome/WriteSome, returns control to the first coroutine, which then also suspends on ReadSome/WriteSome. In that chain of calls, multiple new waits can be added before returning here, so Changes_ can increase by 2 (or potentially more) in a single wake-up cycle.

WakeupReadyHandles()

void NNet::TPollerBase::WakeupReadyHandles ( )

inline

Wakes up all coroutines waiting on ready events.

Iterates over the list of ready events and calls Wakeup() on each.

Yield()

auto NNet::TPollerBase::Yield ( )

inline

Yields execution to the next event loop iteration.

Equivalent to calling Sleep() with a default zero time.

Returns

An awaitable object for yielding execution.

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The documentation for this class was generated from the following file:

• coroio/poller.hpp