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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package time
// Sleep pauses the current goroutine for at least the duration d.
// A negative or zero duration causes Sleep to return immediately.
func Sleep(d Duration)
func nano() int64 {
sec, nsec := now()
return sec*1e9 + int64(nsec)
}
// Interface to timers implemented in package runtime.
// Must be in sync with ../runtime/runtime.h:/^struct.Timer$
type runtimeTimer struct {
i int32
when int64
period int64
f func(int64, interface{}) // NOTE: must not be closure
arg interface{}
}
// when is a helper function for setting the 'when' field of a runtimeTimer.
// It returns what the time will be, in nanoseconds, Duration d in the future.
// If d is negative, it is ignored. If the returned value would be less than
// zero because of an overflow, MaxInt64 is returned.
func when(d Duration) int64 {
if d <= 0 {
return nano()
}
t := nano() + int64(d)
if t < 0 {
t = 1<<63 - 1 // math.MaxInt64
}
return t
}
func startTimer(*runtimeTimer)
func stopTimer(*runtimeTimer) bool
// The Timer type represents a single event.
// When the Timer expires, the current time will be sent on C,
// unless the Timer was created by AfterFunc.
type Timer struct {
C <-chan Time
r runtimeTimer
}
// Stop prevents the Timer from firing.
// It returns true if the call stops the timer, false if the timer has already
// expired or been stopped.
// Stop does not close the channel, to prevent a read from the channel succeeding
// incorrectly.
func (t *Timer) Stop() bool {
return stopTimer(&t.r)
}
// NewTimer creates a new Timer that will send
// the current time on its channel after at least duration d.
func NewTimer(d Duration) *Timer {
c := make(chan Time, 1)
t := &Timer{
C: c,
r: runtimeTimer{
when: when(d),
f: sendTime,
arg: c,
},
}
startTimer(&t.r)
return t
}
// Reset changes the timer to expire after duration d.
// It returns true if the timer had been active, false if the timer had
// expired or been stopped.
func (t *Timer) Reset(d Duration) bool {
w := when(d)
active := stopTimer(&t.r)
t.r.when = w
startTimer(&t.r)
return active
}
func sendTime(now int64, c interface{}) {
// Non-blocking send of time on c.
// Used in NewTimer, it cannot block anyway (buffer).
// Used in NewTicker, dropping sends on the floor is
// the desired behavior when the reader gets behind,
// because the sends are periodic.
select {
case c.(chan Time) <- Unix(0, now):
default:
}
}
// After waits for the duration to elapse and then sends the current time
// on the returned channel.
// It is equivalent to NewTimer(d).C.
func After(d Duration) <-chan Time {
return NewTimer(d).C
}
// AfterFunc waits for the duration to elapse and then calls f
// in its own goroutine. It returns a Timer that can
// be used to cancel the call using its Stop method.
func AfterFunc(d Duration, f func()) *Timer {
t := &Timer{
r: runtimeTimer{
when: when(d),
f: goFunc,
arg: f,
},
}
startTimer(&t.r)
return t
}
func goFunc(now int64, arg interface{}) {
go arg.(func())()
}
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