// It returns true if the timer had been active, false if the timer had
// expired or been stopped.
//
-// Reset should be invoked only on stopped or expired timers with drained channels.
+// For a Timer created with NewTimer, Reset should be invoked only on
+// stopped or expired timers with drained channels.
+//
// If a program has already received a value from t.C, the timer is known
// to have expired and the channel drained, so t.Reset can be used directly.
// If a program has not yet received a value from t.C, however,
// is a race condition between draining the channel and the new timer expiring.
// Reset should always be invoked on stopped or expired channels, as described above.
// The return value exists to preserve compatibility with existing programs.
+//
+// For a Timer created with AfterFunc(d, f), Reset either reschedules
+// when f will run, in which case Reset returns true, or schedules f
+// to run again, in which case it returns false.
+// When Reset returns false, Reset neither waits for the prior f to
+// complete before returning nor does it guarantee that the subsequent
+// goroutine running f does not run concurrently with the prior
+// one. If the caller needs to know whether the prior execution of
+// f is completed, it must coordinate with f explicitly.
func (t *Timer) Reset(d Duration) bool {
if t.r.f == nil {
panic("time: Reset called on uninitialized Timer")