err := srv.listener.Close()
	srv.listenerMutex.Unlock()
	if err != nil {
		return err
	}

	pollIntervalBase := time.Millisecond
	nextPollInterval := func() time.Duration {
		// Add 10% jitter.
		interval := pollIntervalBase + time.Duration(rand.Intn(int(pollIntervalBase/10)))
		// Double and clamp for next time.
		pollIntervalBase *= 2
		if pollIntervalBase > shutdownPollIntervalMax {

	bucketResults := make(chan dataUsageEntryInfo, len(disks))

	// Start async collector/saver.
	// This goroutine owns the cache.
	var saverWg sync.WaitGroup
	saverWg.Add(1)
	go func() {
		// Add jitter to the update time so multiple sets don't sync up.
		updateTime := 30*time.Second + time.Duration(float64(10*time.Second)*rand.Float64())
		t := time.NewTicker(updateTime)
		defer t.Stop()
		defer saverWg.Done()

package pubsub

import (
	"math"
	"math/bits"
)

// Mask allows filtering by a bitset mask.
type Mask uint64

const (
	// MaskAll is the mask for all entries.
	MaskAll Mask = math.MaxUint64
)

// MaskFromMaskable extracts mask from an interface.
func MaskFromMaskable(m Maskable) Mask {
	return Mask(m.Mask())
}

// Contains returns whether *all* flags in other is present in t.
func (t Mask) Contains(other Mask) bool {