mirror of https://github.com/k3s-io/k3s
73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
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package clockwork
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import (
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"time"
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)
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// Ticker provides an interface which can be used instead of directly
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// using the ticker within the time module. The real-time ticker t
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// provides ticks through t.C which becomes now t.Chan() to make
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// this channel requirement definable in this interface.
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type Ticker interface {
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Chan() <-chan time.Time
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Stop()
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}
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type realTicker struct{ *time.Ticker }
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func (rt *realTicker) Chan() <-chan time.Time {
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return rt.C
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}
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type fakeTicker struct {
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c chan time.Time
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stop chan bool
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clock FakeClock
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period time.Duration
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}
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func (ft *fakeTicker) Chan() <-chan time.Time {
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return ft.c
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}
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func (ft *fakeTicker) Stop() {
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ft.stop <- true
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}
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// runTickThread initializes a background goroutine to send the tick time to the ticker channel
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// after every period. Tick events are discarded if the underlying ticker channel does not have
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// enough capacity.
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func (ft *fakeTicker) runTickThread() {
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nextTick := ft.clock.Now().Add(ft.period)
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next := ft.clock.After(ft.period)
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go func() {
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for {
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select {
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case <-ft.stop:
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return
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case <-next:
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// We send the time that the tick was supposed to occur at.
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tick := nextTick
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// Before sending the tick, we'll compute the next tick time and star the clock.After call.
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now := ft.clock.Now()
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// First, figure out how many periods there have been between "now" and the time we were
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// supposed to have trigged, then advance over all of those.
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skipTicks := (now.Sub(tick) + ft.period - 1) / ft.period
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nextTick = nextTick.Add(skipTicks * ft.period)
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// Now, keep advancing until we are past now. This should happen at most once.
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for !nextTick.After(now) {
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nextTick = nextTick.Add(ft.period)
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}
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// Figure out how long between now and the next scheduled tick, then wait that long.
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remaining := nextTick.Sub(now)
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next = ft.clock.After(remaining)
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// Finally, we can actually send the tick.
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select {
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case ft.c <- tick:
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default:
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}
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}
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}
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}()
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}
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