backoff: add a LogLongerThan configuration.
Some programs use frequent short-duration backoffs even under non-error
conditions. They can set this to avoid logging short backoffs when
things are operating normally, but still get messages when longer
backoffs kick in.
type Backoff struct {
n int
+ // Name is the name of this backoff timer, for logging purposes.
Name string
+ // NewTimer is the function that acts like time.NewTimer().
+ // You can override this in unit tests.
NewTimer func(d time.Duration) *time.Timer
+ // LogLongerThan sets the minimum time of a single backoff interval
+ // before we mention it in the log.
+ LogLongerThan time.Duration
}
func (b *Backoff) BackOff(ctx context.Context, err error) {
@@ -31,14 +37,15 @@ func (b *Backoff) BackOff(ctx context.Context, err error) {
// Randomize the delay between 0.5-1.5 x msec, in order
// to prevent accidental "thundering herd" problems.
msec = rand.Intn(msec) + msec/2
- if msec >= 2000 {
+ dur := time.Duration(msec) * time.Millisecond
+ if dur >= b.LogLongerThan {
log.Printf("%s: backoff: %d msec\n", b.Name, msec)
}
newTimer := b.NewTimer
if newTimer == nil {
newTimer = time.NewTimer
}
- t := newTimer(time.Duration(msec) * time.Millisecond)
+ t := newTimer(dur)
select {
case <-ctx.Done():
t.Stop()
