diff options
Diffstat (limited to 'libgo/go/time/sleep.go')
| -rw-r--r-- | libgo/go/time/sleep.go | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/libgo/go/time/sleep.go b/libgo/go/time/sleep.go index e7a2ee2..73114f5 100644 --- a/libgo/go/time/sleep.go +++ b/libgo/go/time/sleep.go @@ -24,7 +24,7 @@ type runtimeTimer struct { // when is a helper function for setting the 'when' field of a runtimeTimer. // It returns what the time will be, in nanoseconds, Duration d in the future. -// If d is negative, it is ignored. If the returned value would be less than +// If d is negative, it is ignored. If the returned value would be less than // zero because of an overflow, MaxInt64 is returned. func when(d Duration) int64 { if d <= 0 { @@ -54,6 +54,14 @@ type Timer struct { // expired or been stopped. // Stop does not close the channel, to prevent a read from the channel succeeding // incorrectly. +// +// To prevent the timer firing after a call to Stop, +// check the return value and drain the channel. For example: +// if !t.Stop() { +// <-t.C +// } +// This cannot be done concurrent to other receives from the Timer's +// channel. func (t *Timer) Stop() bool { if t.r.f == nil { panic("time: Stop called on uninitialized Timer") @@ -80,6 +88,20 @@ func NewTimer(d Duration) *Timer { // Reset changes the timer to expire after duration d. // It returns true if the timer had been active, false if the timer had // expired or been stopped. +// +// To reuse an active timer, always call its Stop method first and—if it had +// expired—drain the value from its channel. For example: +// if !t.Stop() { +// <-t.C +// } +// t.Reset(d) +// This should not be done concurrent to other receives from the Timer's +// channel. +// +// Note that it is not possible to use Reset's return value correctly, as there +// is a race condition between draining the channel and the new timer expiring. +// Reset should always be used in concert with Stop, as described above. +// The return value exists to preserve compatibility with existing programs. func (t *Timer) Reset(d Duration) bool { if t.r.f == nil { panic("time: Reset called on uninitialized Timer") @@ -106,6 +128,9 @@ func sendTime(c interface{}, seq uintptr) { // After waits for the duration to elapse and then sends the current time // on the returned channel. // It is equivalent to NewTimer(d).C. +// The underlying Timer is not recovered by the garbage collector +// until the timer fires. If efficiency is a concern, use NewTimer +// instead and call Timer.Stop if the timer is no longer needed. func After(d Duration) <-chan Time { return NewTimer(d).C } |