Use __builtin_memmove for trivially copyable types
[official-gcc.git] / libgo / go / time / tick.go
blob3d693206a532189305cecd7565b712d644319d65
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.
5 package time
7 import "errors"
9 // A Ticker holds a channel that delivers `ticks' of a clock
10 // at intervals.
11 type Ticker struct {
12 C <-chan Time // The channel on which the ticks are delivered.
13 r runtimeTimer
16 // NewTicker returns a new Ticker containing a channel that will send the
17 // time with a period specified by the duration argument.
18 // It adjusts the intervals or drops ticks to make up for slow receivers.
19 // The duration d must be greater than zero; if not, NewTicker will panic.
20 // Stop the ticker to release associated resources.
21 func NewTicker(d Duration) *Ticker {
22 if d <= 0 {
23 panic(errors.New("non-positive interval for NewTicker"))
25 // Give the channel a 1-element time buffer.
26 // If the client falls behind while reading, we drop ticks
27 // on the floor until the client catches up.
28 c := make(chan Time, 1)
29 t := &Ticker{
30 C: c,
31 r: runtimeTimer{
32 when: when(d),
33 period: int64(d),
34 f: sendTime,
35 arg: c,
38 startTimer(&t.r)
39 return t
42 // Stop turns off a ticker. After Stop, no more ticks will be sent.
43 // Stop does not close the channel, to prevent a read from the channel succeeding
44 // incorrectly.
45 func (t *Ticker) Stop() {
46 stopTimer(&t.r)
49 // Tick is a convenience wrapper for NewTicker providing access to the ticking
50 // channel only. While Tick is useful for clients that have no need to shut down
51 // the Ticker, be aware that without a way to shut it down the underlying
52 // Ticker cannot be recovered by the garbage collector; it "leaks".
53 // Unlike NewTicker, Tick will return nil if d <= 0.
54 func Tick(d Duration) <-chan Time {
55 if d <= 0 {
56 return nil
58 return NewTicker(d).C