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80 lines
2.0 KiB
Go
80 lines
2.0 KiB
Go
// Package timer is a Go timer implementation with a fixed Reset behavior.
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package timer
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import (
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"time"
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)
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// The Timer type represents a single event. When the Timer expires,
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// the current time will be sent on C, unless the Timer was created by AfterFunc.
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// A Timer must be created with NewTimer. NewStoppedTimer or AfterFunc.
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type Timer struct {
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C <-chan time.Time
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i int // heap index.
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when int64 // Timer wakes up at when.
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// f is called in a locked context on timeout. This function must not block
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// and must behave well-defined.
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f func(t *time.Time)
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// reset is called in a locked context. This function must not block
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// and must behave well-defined.
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reset func()
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}
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// NewTimer creates a new Timer that will send the current time on its
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// channel after at least duration d.
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func NewTimer(d time.Duration) *Timer {
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t := NewStoppedTimer()
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addTimer(t, d)
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return t
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}
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// NewStoppedTimer creates a new stopped Timer.
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func NewStoppedTimer() *Timer {
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c := make(chan time.Time, 1)
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t := &Timer{
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C: c,
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f: func(t *time.Time) {
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// Don't block.
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select {
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case c <- *t:
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default:
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}
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},
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reset: func() {
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// Empty the channel if filled.
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select {
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case <-c:
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default:
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}
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},
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}
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return t
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}
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// Stop prevents the Timer from firing.
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// It returns true if the call stops the timer,
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// false if the timer has already expired or been stopped.
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// Stop does not close the channel, to prevent a read from
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// the channel succeeding incorrectly.
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func (t *Timer) Stop() (wasActive bool) {
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if t.f == nil {
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panic("timer: Stop called on uninitialized Timer")
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}
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return delTimer(t)
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}
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// Reset changes the timer to expire after duration d.
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// It returns true if the timer had been active,
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// false if the timer had expired or been stopped.
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// The channel t.C is cleared and calling t.Reset() behaves as creating a
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// new Timer.
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func (t *Timer) Reset(d time.Duration) bool {
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if t.f == nil {
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panic("timer: Reset called on uninitialized Timer")
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}
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return resetTimer(t, d)
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}
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