Atomic high-resolution timer with selectable clock source and unit. 更多...

#include <elapsed_timer.h>

vlink::ElapsedTimer 的协作图:

Public 类型
enum	Method : uint8_t { kCpuTimestamp = 0 , kCpuActiveTime = 1 }
	Clock source selector. 更多...

enum	Accuracy : uint8_t { kMilli = 0 , kMicro = 1 , kNano = 2 }
	Precision selector for stored and returned time values. 更多...

Public 成员函数
	ElapsedTimer () noexcept
	Constructs a timer with default method (`kCpuTimestamp`) and accuracy (`kMilli`). 更多...

	ElapsedTimer (Method method) noexcept
	Constructs a timer with the given clock source and default millisecond accuracy. 更多...

	ElapsedTimer (Accuracy accuracy) noexcept
	Constructs a timer with the default clock source and the given accuracy. 更多...

	ElapsedTimer (Method method, Accuracy accuracy) noexcept
	Constructs a timer with the given clock source and accuracy. 更多...

	ElapsedTimer (const ElapsedTimer &target) noexcept
	Copy constructor; copies the snapshot value and configuration. 更多...

	ElapsedTimer (ElapsedTimer &&target) noexcept
	Move constructor; equivalent to copy for this snapshot-valued type. 更多...

	~ElapsedTimer () noexcept
	Destructor. 更多...

ElapsedTimer &	operator= (const ElapsedTimer &target) noexcept
	Copy assignment; copies the snapshot value and configuration. 更多...

ElapsedTimer &	operator= (ElapsedTimer &&) noexcept
	Move assignment; equivalent to copy assignment for this snapshot-valued type. 更多...

Method	get_method () const noexcept
	Returns the clock source this timer was configured with. 更多...

Accuracy	get_accuracy () const noexcept
	Returns the precision this timer was configured with. 更多...

void	start () noexcept
	Records the current time as the start reference if the timer is inactive. 更多...

void	stop () noexcept
	Marks the timer inactive by writing `-1` into the start reference. 更多...

int64_t	restart () noexcept
	Atomically reads the elapsed time and starts a new measurement from now. 更多...

bool	is_active () const noexcept
	Reports whether the timer is currently measuring. 更多...

int64_t	get () const noexcept
	Returns the elapsed time since `start` without altering state. 更多...

静态 Public 成员函数
static uint64_t	get_sys_timestamp (Accuracy accuracy=kMilli, bool high_resolution=true) noexcept
	Returns the current wall-clock timestamp. 更多...

static uint64_t	get_cpu_timestamp (Accuracy accuracy=kMilli, bool high_resolution=true) noexcept
	Returns the current monotonic CPU timestamp. 更多...

static uint64_t	get_cpu_active_time (Accuracy accuracy=kMilli) noexcept
	Returns the cumulative CPU time consumed by the current process. 更多...

详细描述

Atomic high-resolution timer with selectable clock source and unit.

Records the elapsed time between start and get / restart. Marked final. Copy and move constructors copy the snapshot value (not exclusive ownership), allowing trivial propagation through wrapper structures.

成员枚举类型说明

◆ Accuracy

enum vlink::ElapsedTimer::Accuracy : uint8_t

Precision selector for stored and returned time values.

枚举值
kMilli	Millisecond precision.
kMicro	Microsecond precision.
kNano	Nanosecond precision.

◆ Method

enum vlink::ElapsedTimer::Method : uint8_t

Clock source selector.

枚举值
kCpuTimestamp	Monotonic wall clock (`steady_clock` for instance timing).
kCpuActiveTime	Process CPU time (user + kernel via `getrusage` / `GetProcessTimes`).

构造及析构函数说明

◆ ElapsedTimer() [1/6]

vlink::ElapsedTimer::ElapsedTimer ( )

noexcept

Constructs a timer with default method (kCpuTimestamp) and accuracy (kMilli).

The timer is inactive on construction; call start to begin measuring.

◆ ElapsedTimer() [2/6]

vlink::ElapsedTimer::ElapsedTimer ( Method method )

explicitnoexcept

Constructs a timer with the given clock source and default millisecond accuracy.

参数

method Clock source.

◆ ElapsedTimer() [3/6]

vlink::ElapsedTimer::ElapsedTimer ( Accuracy accuracy )

explicitnoexcept

Constructs a timer with the default clock source and the given accuracy.

参数

accuracy Precision of returned values.

◆ ElapsedTimer() [4/6]

vlink::ElapsedTimer::ElapsedTimer	(	Method	method,
		Accuracy	accuracy
	)

explicitnoexcept

Constructs a timer with the given clock source and accuracy.

参数

method	Clock source.
accuracy	Precision of returned values.

◆ ElapsedTimer() [5/6]

vlink::ElapsedTimer::ElapsedTimer ( const ElapsedTimer & target )

noexcept

Copy constructor; copies the snapshot value and configuration.

参数

target Source timer.

◆ ElapsedTimer() [6/6]

vlink::ElapsedTimer::ElapsedTimer ( ElapsedTimer && target )

noexcept

Move constructor; equivalent to copy for this snapshot-valued type.

参数

target Source timer.

◆ ~ElapsedTimer()

vlink::ElapsedTimer::~ElapsedTimer ( )

noexcept

Destructor.

成员函数说明

◆ get()

int64_t vlink::ElapsedTimer::get ( ) const

noexcept

Returns the elapsed time since start without altering state.

返回: Elapsed value in the configured unit, or -1 when inactive.

◆ get_accuracy()

Accuracy vlink::ElapsedTimer::get_accuracy ( ) const

noexcept

Returns the precision this timer was configured with.

返回: Configured precision.

◆ get_cpu_active_time()

static uint64_t vlink::ElapsedTimer::get_cpu_active_time ( Accuracy accuracy = kMilli )

staticnoexcept

Returns the cumulative CPU time consumed by the current process.

On POSIX uses getrusage(RUSAGE_SELF); on Windows uses GetProcessTimes. The value is cumulative; subtract two samples to obtain a delta.

参数

accuracy Desired precision. Default: kMilli.

返回: Process CPU time in the requested unit.

◆ get_cpu_timestamp()

static uint64_t vlink::ElapsedTimer::get_cpu_timestamp	(	Accuracy	accuracy = `kMilli`,
		bool	high_resolution = `true`
	)

staticnoexcept

Returns the current monotonic CPU timestamp.

On Linux uses CLOCK_MONOTONIC_RAW (immune to NTP) when high_resolution is true; otherwise uses std::chrono::steady_clock. Windows always uses steady_clock.

参数

accuracy	Desired precision. Default: `kMilli`.
high_resolution	Linux-only switch for `clock_gettime`. Default: `true`.

返回: Monotonic timestamp in the requested unit.

◆ get_method()

Method vlink::ElapsedTimer::get_method ( ) const

noexcept

Returns the clock source this timer was configured with.

返回: Configured clock source.

◆ get_sys_timestamp()

static uint64_t vlink::ElapsedTimer::get_sys_timestamp	(	Accuracy	accuracy = `kMilli`,
		bool	high_resolution = `true`
	)

staticnoexcept

Returns the current wall-clock timestamp.

On Linux uses clock_gettime with CLOCK_REALTIME when high_resolution is true, falling back to std::chrono::system_clock otherwise. On Windows always uses std::chrono::system_clock.

参数

accuracy	Desired precision. Default: `kMilli`.
high_resolution	Linux-only switch for `clock_gettime`. Default: `true`.

返回: Wall-clock timestamp in the requested unit.

◆ is_active()

bool vlink::ElapsedTimer::is_active ( ) const

noexcept

Reports whether the timer is currently measuring.

返回: true when start has produced a non-sentinel reference.

◆ operator=() [1/2]

ElapsedTimer& vlink::ElapsedTimer::operator= ( const ElapsedTimer & target )

noexcept

Copy assignment; copies the snapshot value and configuration.

参数

target Source timer.

返回: Reference to *this.

◆ operator=() [2/2]

ElapsedTimer& vlink::ElapsedTimer::operator= ( ElapsedTimer && )

noexcept

Move assignment; equivalent to copy assignment for this snapshot-valued type.

返回: Reference to *this.

◆ restart()

int64_t vlink::ElapsedTimer::restart ( )

noexcept

Atomically reads the elapsed time and starts a new measurement from now.

Performs a single atomic exchange. When the timer was already active the returned value is the elapsed time since the last start; when it was inactive the return is negative (the raw sentinel) and the timer is left active starting from this call.

返回: Elapsed time in the configured unit, or a negative value if the timer was inactive.

◆ start()

void vlink::ElapsedTimer::start ( )

noexcept

Records the current time as the start reference if the timer is inactive.

Uses a compare-and-swap on the internal atomic so concurrent calls compete and only one wins. Already-active timers are unchanged; call stop first to rearm.

◆ stop()

void vlink::ElapsedTimer::stop ( )

noexcept

Marks the timer inactive by writing -1 into the start reference.

After stop the timer reports is_active() == false and get() returns -1.

该类的文档由以下文件生成:

include/vlink/base/elapsed_timer.h

Public 类型

Public 成员函数

静态 Public 成员函数

详细描述

成员枚举类型说明

◆ Accuracy

◆ Method

构造及析构函数说明

◆ ElapsedTimer() [1/6]

◆ ElapsedTimer() [2/6]

◆ ElapsedTimer() [3/6]

◆ ElapsedTimer() [4/6]

◆ ElapsedTimer() [5/6]

◆ ElapsedTimer() [6/6]

◆ ~ElapsedTimer()

成员函数说明

◆ get()

◆ get_accuracy()

◆ get_cpu_active_time()

◆ get_cpu_timestamp()

◆ get_method()

◆ get_sys_timestamp()

◆ is_active()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ restart()

◆ start()

◆ stop()