mclock

Documentation

Overview

Package mclock is a wrapper for a monotonic clock source

Index

• type AbsTime
  • func Now() AbsTime
  • func (t AbsTime) Add(d time.Duration) AbsTime
  • func (t AbsTime) Sub(t2 AbsTime) time.Duration
• type Alarm
  • func NewAlarm(clock Clock) *Alarm
  • func (e *Alarm) C() <-chan struct{}
  • func (e *Alarm) Schedule(time AbsTime)
  • func (e *Alarm) Stop()
• type ChanTimer
• type Clock
• type Simulated
  • func (s *Simulated) ActiveTimers() int
  • func (s *Simulated) After(d time.Duration) <-chan AbsTime
  • func (s *Simulated) AfterFunc(d time.Duration, fn func()) Timer
  • func (s *Simulated) NewTimer(d time.Duration) ChanTimer
  • func (s *Simulated) Now() AbsTime
  • func (s *Simulated) Run(d time.Duration)
  • func (s *Simulated) Sleep(d time.Duration)
  • func (s *Simulated) WaitForTimers(n int)
• type System
  • func (c System) After(d time.Duration) <-chan AbsTime
  • func (c System) AfterFunc(d time.Duration, f func()) Timer
  • func (c System) NewTimer(d time.Duration) ChanTimer
  • func (c System) Now() AbsTime
  • func (c System) Sleep(d time.Duration)
• type Timer

Types

type AbsTime

type AbsTime int64

AbsTime represents absolute monotonic time.

func Now

func Now() AbsTime

Now returns the current absolute monotonic time.

func (AbsTime) Add

func (t AbsTime) Add(d time.Duration) AbsTime

Add returns t + d as absolute time.

func (AbsTime) Sub

func (t AbsTime) Sub(t2 AbsTime) time.Duration

Sub returns t - t2 as a duration.

type Alarm

type Alarm struct {
	// contains filtered or unexported fields
}

Alarm sends timed notifications on a channel. This is very similar to a regular timer, but is easier to use in code that needs to re-schedule the same timer over and over.

When scheduling an Alarm, the channel returned by C() will receive a value no later than the scheduled time. An Alarm can be reused after it has fired and can also be canceled by calling Stop.

func NewAlarm

func NewAlarm(clock Clock) *Alarm

NewAlarm creates an Alarm.

func (*Alarm) C

func (e *Alarm) C() <-chan struct{}

C returns the alarm notification channel. This channel remains identical for the entire lifetime of the alarm, and is never closed.

func (*Alarm) Schedule

func (e *Alarm) Schedule(time AbsTime)

Schedule sets the alarm to fire no later than the given time. If the alarm was already scheduled but has not fired yet, it may fire earlier than the newly-scheduled time.

func (*Alarm) Stop

func (e *Alarm) Stop()

Stop cancels the alarm and drains the channel. This method is not safe for concurrent use.

type ChanTimer

type ChanTimer interface {
	Timer

	// The channel returned by C receives a value when the timer expires.
	C() <-chan AbsTime
	// Reset reschedules the timer with a new timeout.
	// It should be invoked only on stopped or expired timers with drained channels.
	Reset(time.Duration)
}

ChanTimer is a cancellable event created by NewTimer.

type Clock

type Clock interface {
	Now() AbsTime
	Sleep(time.Duration)
	NewTimer(time.Duration) ChanTimer
	After(time.Duration) <-chan AbsTime
	AfterFunc(d time.Duration, f func()) Timer
}

The Clock interface makes it possible to replace the monotonic system clock with a simulated clock.

type Simulated

type Simulated struct {
	// contains filtered or unexported fields
}

Simulated implements a virtual Clock for reproducible time-sensitive tests. It simulates a scheduler on a virtual timescale where actual processing takes zero time.

The virtual clock doesn't advance on its own, call Run to advance it and execute timers. Since there is no way to influence the Go scheduler, testing timeout behaviour involving goroutines needs special care. A good way to test such timeouts is as follows: First perform the action that is supposed to time out. Ensure that the timer you want to test is created. Then run the clock until after the timeout. Finally observe the effect of the timeout using a channel or semaphore.

func (*Simulated) ActiveTimers

func (s *Simulated) ActiveTimers() int

ActiveTimers returns the number of timers that haven't fired.

func (*Simulated) After

func (s *Simulated) After(d time.Duration) <-chan AbsTime

After returns a channel which receives the current time after the clock has advanced by d.

func (*Simulated) AfterFunc

func (s *Simulated) AfterFunc(d time.Duration, fn func()) Timer

AfterFunc runs fn after the clock has advanced by d. Unlike with the system clock, fn runs on the goroutine that calls Run.

func (*Simulated) NewTimer

func (s *Simulated) NewTimer(d time.Duration) ChanTimer

NewTimer creates a timer which fires when the clock has advanced by d.

func (*Simulated) Now

func (s *Simulated) Now() AbsTime

Now returns the current virtual time.

func (*Simulated) Run

func (s *Simulated) Run(d time.Duration)

Run moves the clock by the given duration, executing all timers before that duration.

func (*Simulated) Sleep

func (s *Simulated) Sleep(d time.Duration)

Sleep blocks until the clock has advanced by d.

func (*Simulated) WaitForTimers

func (s *Simulated) WaitForTimers(n int)

WaitForTimers waits until the clock has at least n scheduled timers.

type System

type System struct{}

System implements Clock using the system clock.

func (System) After

func (c System) After(d time.Duration) <-chan AbsTime

After returns a channel which receives the current time after d has elapsed.

func (System) AfterFunc

func (c System) AfterFunc(d time.Duration, f func()) Timer

AfterFunc runs f on a new goroutine after the duration has elapsed.

func (System) NewTimer

func (c System) NewTimer(d time.Duration) ChanTimer

NewTimer creates a timer which can be rescheduled.

func (System) Now

func (c System) Now() AbsTime

Now returns the current monotonic time.

func (System) Sleep

func (c System) Sleep(d time.Duration)

Sleep blocks for the given duration.

type Timer

type Timer interface {
	// Stop cancels the timer. It returns false if the timer has already
	// expired or been stopped.
	Stop() bool
}

Timer is a cancellable event created by AfterFunc.