Channels, Timeouts, and Tickers

The time package has some interesting functionality to use in combination with channels. It contains a struct time.Ticker, which is an object that repeatedly sends a time value on a contained channel C at a specified time interval:

type Ticker struct {
  C <-chan Time // the channel on which the ticks are delivered.
  // contains filtered or unexported fields
  ...
}

A Ticker can be very useful when, during the execution of goroutines, something (logging a status, a printout, a calculation, and so on) has to be done periodically at a certain time interval. It is stopped with Stop(); use this in a defer statement. All this fits nicely in a select statement:

ticker := time.NewTicker(updateInterval)
defer ticker.Stop()
...
select {
  case u:= <- ch1:
    ...
  case v:= <- ch2:
    ...
  case <- ticker.C:

   logState(status) // e.g. call some logging function logState

  default: // no value ready to be received
    ...
}

The time.Tick() function with signature func Tick(d Duration) <-chan Time is useful when you only need access to the return channel and don’t need to shut it down. It sends out the time on the return channel with periodicity d, which is a number of nanoseconds. It is handy to use when ...