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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
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{})
arg interface{}
}
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 stopped.
func (t *Timer) Stop() (ok bool) {
return stopTimer(&t.r)
}
// NewTimer creates a new Timer that will send
// the current time on its channel after at least ns nanoseconds.
func NewTimer(d Duration) *Timer {
c := make(chan Time, 1)
t := &Timer{
C: c,
r: runtimeTimer{
when: nano() + int64(d),
f: sendTime,
arg: c,
},
}
startTimer(&t.r)
return t
}
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(ns).C.
func After(d Duration) <-chan Time {
return NewTimer(d).C
}
// AfterFunc waits at least ns nanoseconds before calling f
// in its own goroutine. It returns a Timer that can
// be used to cancel the call using its Stop method.
func AfterFunc(ns int64, f func()) *Timer {
t := &Timer{
r: runtimeTimer{
when: nano() + ns,
f: goFunc,
arg: f,
},
}
startTimer(&t.r)
return t
}
func goFunc(now int64, arg interface{}) {
go arg.(func())()
}
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