vlink::DeadlineTimer Class Reference

Cache-line aligned atomic deadline counter with millisecond / microsecond / nanosecond precision. More...

#include <deadline_timer.h>

Collaboration diagram for vlink::DeadlineTimer:

Public Types
using	Accuracy = ElapsedTimer::Accuracy
	Precision unit alias inherited from ElapsedTimer::Accuracy. More...

Public Member Functions
	DeadlineTimer () noexcept
	Constructs an invalid timer with no deadline set. More...
	DeadlineTimer (int64_t interval, Accuracy accuracy=ElapsedTimer::kMilli) noexcept
	Constructs a timer that expires interval units in the future. More...
	DeadlineTimer (const DeadlineTimer &other) noexcept
	Copy constructor; copies the stored deadline and accuracy. More...
	DeadlineTimer (DeadlineTimer &&other) noexcept
	Move constructor; equivalent to copy because the timer holds only POD state. More...
	~DeadlineTimer () noexcept
	Destructor. More...
DeadlineTimer &	operator= (const DeadlineTimer &other) noexcept
	Copy assignment; replaces the stored deadline and accuracy. More...
DeadlineTimer &	operator= (DeadlineTimer &&other) noexcept
	Move assignment; equivalent to copy assignment for this POD-state type. More...
void	set_deadline (int64_t interval) noexcept
	Sets the deadline interval units after the current monotonic timestamp. More...
void	set_deadline_abs (uint64_t abs_deadline) noexcept
	Sets an absolute deadline timestamp directly. More...
void	reset () noexcept
	Resets the timer to the invalid state. More...
uint64_t	deadline () const noexcept
	Returns the stored absolute deadline timestamp. More...
int64_t	remaining_time () const noexcept
	Returns the time remaining until the deadline. More...
bool	has_expired () const noexcept
	Reports whether the current time has passed the stored deadline. More...
bool	is_valid () const noexcept
	Reports whether a deadline has been set. More...
Accuracy	get_accuracy () const noexcept
	Returns the precision configured for this timer. More...

Detailed Description

Cache-line aligned atomic deadline counter with millisecond / microsecond / nanosecond precision.

Reuses ElapsedTimer::Accuracy for time precision. Reads and writes go through a single std::atomic<uint64_t> aligned to 64 bytes to avoid false sharing when several timers share a structure. An invalid (unset) timer stores 0 and never reports expiry.

Member Typedef Documentation

Accuracy

using vlink::DeadlineTimer::Accuracy = ElapsedTimer::Accuracy

Precision unit alias inherited from ElapsedTimer::Accuracy.

Constructor & Destructor Documentation

DeadlineTimer() [1/4]

vlink::DeadlineTimer::DeadlineTimer ( )

noexcept

Constructs an invalid timer with no deadline set.

is_valid returns false and has_expired returns false until set_deadline or set_deadline_abs is called.

DeadlineTimer() [2/4]

vlink::DeadlineTimer::DeadlineTimer ( int64_t  interval, Accuracy  accuracy = ElapsedTimer::kMilli  )

explicitnoexcept

Constructs a timer that expires interval units in the future.

The absolute deadline is computed as the current monotonic timestamp plus interval. A non-positive interval leaves the timer invalid.

Parameters

interval	Duration until expiry in accuracy units.
accuracy	Precision of stored timestamps. Default: ElapsedTimer::kMilli.

DeadlineTimer() [3/4]

vlink::DeadlineTimer::DeadlineTimer ( const DeadlineTimer &  other )

noexcept

Copy constructor; copies the stored deadline and accuracy.

Parameters

other

Source timer.

DeadlineTimer() [4/4]

vlink::DeadlineTimer::DeadlineTimer ( DeadlineTimer &&  other )

noexcept

Move constructor; equivalent to copy because the timer holds only POD state.

Parameters

other

Source timer.

~DeadlineTimer()

vlink::DeadlineTimer::~DeadlineTimer ( )

noexcept

Destructor.

Member Function Documentation

deadline()

uint64_t vlink::DeadlineTimer::deadline ( ) const

noexcept

Returns the stored absolute deadline timestamp.

Returns

Deadline value in the configured accuracy unit. 0 indicates an invalid timer.

get_accuracy()

Accuracy vlink::DeadlineTimer::get_accuracy ( ) const

noexcept

Returns the precision configured for this timer.

Returns

Accuracy unit chosen at construction.

has_expired()

bool vlink::DeadlineTimer::has_expired ( ) const

noexcept

Reports whether the current time has passed the stored deadline.

Returns

true when expired; always false for invalid timers.

is_valid()

bool vlink::DeadlineTimer::is_valid ( ) const

noexcept

Reports whether a deadline has been set.

Returns

true when deadline() is non-zero.

operator=() [1/2]

DeadlineTimer& vlink::DeadlineTimer::operator= ( const DeadlineTimer &  other )

noexcept

Copy assignment; replaces the stored deadline and accuracy.

Parameters

other

Source timer.

Returns

Reference to *this.

operator=() [2/2]

DeadlineTimer& vlink::DeadlineTimer::operator= ( DeadlineTimer &&  other )

noexcept

Move assignment; equivalent to copy assignment for this POD-state type.

Parameters

other

Source timer.

Returns

Reference to *this.

remaining_time()

int64_t vlink::DeadlineTimer::remaining_time ( ) const

noexcept

Returns the time remaining until the deadline.

Computed as (deadline - current_cpu_timestamp); clamped to 0 once the deadline has been reached or when the timer is invalid.

Returns

Remaining time in the configured accuracy unit; 0 when invalid or expired.

reset()

void vlink::DeadlineTimer::reset ( )

noexcept

Resets the timer to the invalid state.

After reset, is_valid returns false and has_expired returns false.

set_deadline()

void vlink::DeadlineTimer::set_deadline ( int64_t  interval )

noexcept

Sets the deadline interval units after the current monotonic timestamp.

A non-positive interval clears the timer (equivalent to reset).

Parameters

interval

Duration until expiry in the configured accuracy unit.

set_deadline_abs()

void vlink::DeadlineTimer::set_deadline_abs ( uint64_t  abs_deadline )

noexcept

Sets an absolute deadline timestamp directly.

abs_deadline must be expressed in the same unit and time base as the configured accuracy; obtain it via ElapsedTimer::get_cpu_timestamp(accuracy).

Parameters

abs_deadline

Absolute monotonic deadline.

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

• include/vlink/base/deadline_timer.h