...
Run Format

Source file src/pkg/time/tick.go

     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.
     4	
     5	package time
     6	
     7	import "errors"
     8	
     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
    14	}
    15	
    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"))
    24		}
    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,
    36			},
    37		}
    38		startTimer(&t.r)
    39		return t
    40	}
    41	
    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)
    47	}
    48	
    49	// Tick is a convenience wrapper for NewTicker providing access to the ticking
    50	// channel only.  Useful for clients that have no need to shut down the ticker.
    51	func Tick(d Duration) <-chan Time {
    52		if d <= 0 {
    53			return nil
    54		}
    55		return NewTicker(d).C
    56	}
    57	

View as plain text