time: add After
Permits one to easily put a timeout in a select:
select {
case <-ch:
// foo
case <-time.After(1e6):
// bar
}
R=r, rog, rsc, sameer1, PeterGo, iant, nigeltao_gnome
CC=golang-dev
https://golang.org/cl/2321043
diff --git a/src/pkg/time/sleep.go b/src/pkg/time/sleep.go
index 5de5374..702ced1 100644
--- a/src/pkg/time/sleep.go
+++ b/src/pkg/time/sleep.go
@@ -9,18 +9,38 @@
"syscall"
)
-// Sleep pauses the current goroutine for at least ns nanoseconds. Higher resolution
-// sleeping may be provided by syscall.Nanosleep on some operating systems.
+// Sleep pauses the current goroutine for at least ns nanoseconds.
+// Higher resolution sleeping may be provided by syscall.Nanosleep
+// on some operating systems.
func Sleep(ns int64) os.Error {
- // TODO(cw): use monotonic-time once it's available
+ _, err := sleep(Nanoseconds(), ns)
+ return err
+}
+
+// After waits at least ns nanoseconds before sending the current time
+// on the returned channel.
+func After(ns int64) <-chan int64 {
t := Nanoseconds()
+ ch := make(chan int64, 1)
+ go func() {
+ t, _ = sleep(t, ns)
+ ch <- t
+ }()
+ return ch
+}
+
+// sleep takes the current time and a duration,
+// pauses for at least ns nanoseconds, and
+// returns the current time and an error.
+func sleep(t, ns int64) (int64, os.Error) {
+ // TODO(cw): use monotonic-time once it's available
end := t + ns
for t < end {
errno := syscall.Sleep(end - t)
if errno != 0 && errno != syscall.EINTR {
- return os.NewSyscallError("sleep", errno)
+ return 0, os.NewSyscallError("sleep", errno)
}
t = Nanoseconds()
}
- return nil
+ return t, nil
}
diff --git a/src/pkg/time/sleep_test.go b/src/pkg/time/sleep_test.go
index 7ec6c49..4934a38 100644
--- a/src/pkg/time/sleep_test.go
+++ b/src/pkg/time/sleep_test.go
@@ -24,3 +24,15 @@
t.Fatalf("Sleep(%d) slept for only %d ns", delay, duration)
}
}
+
+func TestAfter(t *testing.T) {
+ const delay = int64(100e6)
+ start := Nanoseconds()
+ end := <-After(delay)
+ if duration := Nanoseconds() - start; duration < delay {
+ t.Fatalf("After(%d) slept for only %d ns", delay, duration)
+ }
+ if min := start + delay; end < min {
+ t.Fatalf("After(%d) expect >= %d, got %d", delay, min, end)
+ }
+}
