libgo/go/time/sleep.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 (
   8         "os"
   9         "syscall"
  10 )
  11
  12 // Sleep pauses the current goroutine for at least ns nanoseconds.
  13 // Higher resolution sleeping may be provided by syscall.Nanosleep
  14 // on some operating systems.
  15 func Sleep(ns int64) os.Error {
  16         _, err := sleep(Nanoseconds(), ns)
  17         return err
  18 }
  19
  20 // After waits at least ns nanoseconds before sending the current time
  21 // on the returned channel.
  22 func After(ns int64) <-chan int64 {
  23         t := Nanoseconds()
  24         ch := make(chan int64, 1)
  25         go func() {
  26                 t, _ = sleep(t, ns)
  27                 ch <- t
  28         }()
  29         return ch
  30 }
  31
  32 // sleep takes the current time and a duration,
  33 // pauses for at least ns nanoseconds, and
  34 // returns the current time and an error.
  35 func sleep(t, ns int64) (int64, os.Error) {
  36         // TODO(cw): use monotonic-time once it's available
  37         end := t + ns
  38         for t < end {
  39                 errno := syscall.Sleep(end - t)
  40                 if errno != 0 && errno != syscall.EINTR {
  41                         return 0, os.NewSyscallError("sleep", errno)
  42                 }
  43                 t = Nanoseconds()
  44         }
  45         return t, nil
  46 }