1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 // Sleep pauses the current goroutine for at least the duration d.
8 // A negative or zero duration causes Sleep to return immediately.
11 // runtimeNano returns the current value of the runtime clock in nanoseconds.
12 func runtimeNano() int64
14 // Interface to timers implemented in package runtime.
15 // Must be in sync with ../runtime/runtime.h:/^struct.Timer$
16 type runtimeTimer
struct {
20 f
func(interface{}, uintptr) // NOTE: must not be closure
25 // when is a helper function for setting the 'when' field of a runtimeTimer.
26 // It returns what the time will be, in nanoseconds, Duration d in the future.
27 // If d is negative, it is ignored. If the returned value would be less than
28 // zero because of an overflow, MaxInt64 is returned.
29 func when(d Duration
) int64 {
33 t
:= runtimeNano() + int64(d
)
35 t
= 1<<63 - 1 // math.MaxInt64
40 func startTimer(*runtimeTimer
)
41 func stopTimer(*runtimeTimer
) bool
43 // The Timer type represents a single event.
44 // When the Timer expires, the current time will be sent on C,
45 // unless the Timer was created by AfterFunc.
46 // A Timer must be created with NewTimer or AfterFunc.
52 // Stop prevents the Timer from firing.
53 // It returns true if the call stops the timer, false if the timer has already
54 // expired or been stopped.
55 // Stop does not close the channel, to prevent a read from the channel succeeding
57 func (t
*Timer
) Stop() bool {
59 panic("time: Stop called on uninitialized Timer")
61 return stopTimer(&t
.r
)
64 // NewTimer creates a new Timer that will send
65 // the current time on its channel after at least duration d.
66 func NewTimer(d Duration
) *Timer
{
67 c
:= make(chan Time
, 1)
80 // Reset changes the timer to expire after duration d.
81 // It returns true if the timer had been active, false if the timer had
82 // expired or been stopped.
83 func (t
*Timer
) Reset(d Duration
) bool {
85 panic("time: Reset called on uninitialized Timer")
88 active
:= stopTimer(&t
.r
)
94 func sendTime(c
interface{}, seq
uintptr) {
95 // Non-blocking send of time on c.
96 // Used in NewTimer, it cannot block anyway (buffer).
97 // Used in NewTicker, dropping sends on the floor is
98 // the desired behavior when the reader gets behind,
99 // because the sends are periodic.
101 case c
.(chan Time
) <- Now():
106 // After waits for the duration to elapse and then sends the current time
107 // on the returned channel.
108 // It is equivalent to NewTimer(d).C.
109 func After(d Duration
) <-chan Time
{
113 // AfterFunc waits for the duration to elapse and then calls f
114 // in its own goroutine. It returns a Timer that can
115 // be used to cancel the call using its Stop method.
116 func AfterFunc(d Duration
, f
func()) *Timer
{
128 func goFunc(arg
interface{}, seq
uintptr) {