// even if updating the value errors out.
	// Returns the last good value AND the error.
	ReturnLastGood bool

	// If NoWait is set, Get() will return the last good value,
	// if TTL has expired but 2x TTL has not yet passed,
	// but will fetch a new value in the background.
	NoWait bool
}

// Cache contains a synchronized value that is considered valid
// for a specific amount of time.

package clause

const (
	LockingStrengthUpdate    = "UPDATE"
	LockingStrengthShare     = "SHARE"
	LockingOptionsSkipLocked = "SKIP LOCKED"
	LockingOptionsNoWait     = "NOWAIT"
)

type Locking struct {
	Strength string
	Table    Table
	Options  string
}

// Name where clause name
func (locking Locking) Name() string {
	return "FOR"
}

// Build build where clause
func (locking Locking) Build(builder Builder) {

		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Locking{Strength: clause.LockingStrengthUpdate, Options: clause.LockingOptionsNoWait}},
			"SELECT * FROM `users` FOR UPDATE NOWAIT", nil,
		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Locking{Strength: clause.LockingStrengthUpdate, Options: clause.LockingOptionsSkipLocked}},
			"SELECT * FROM `users` FOR UPDATE SKIP LOCKED", nil,

var bucketStorageCache = cachevalue.New[DataUsageInfo]()

// Init initialize bucket quota.
func (sys *BucketQuotaSys) Init(objAPI ObjectLayer) {
	bucketStorageCache.InitOnce(10*time.Second,
		cachevalue.Opts{ReturnLastGood: true, NoWait: true},
		func(ctx context.Context) (DataUsageInfo, error) {
			if objAPI == nil {
				return DataUsageInfo{}, errServerNotInitialized
			}
			ctx, done := context.WithTimeout(ctx, 2*time.Second)
			defer done()

		return map[string]uint64{}, nil
	}

	cache := dataUsageCache{}

	prefixUsageCache.InitOnce(30*time.Second,
		// No need to fail upon Update() error, fallback to old value.
		cachevalue.Opts{ReturnLastGood: true, NoWait: true},
		func(ctx context.Context) (map[string]uint64, error) {
			m := make(map[string]uint64)
			for _, pool := range z.serverPools {
				for _, er := range pool.sets {
					// Load bucket usage prefixes

	sysCPUSystem    = "system"
	sysCPUUser      = "user"
)

var (
	sysCPUAvgIdleMD   = NewGaugeMD(sysCPUAvgIdle, "Average CPU idle time")
	sysCPUAvgIOWaitMD = NewGaugeMD(sysCPUAvgIOWait, "Average CPU IOWait time")
	sysCPULoadMD      = NewGaugeMD(sysCPULoad, "CPU load average 1min")
	sysCPULoadPercMD  = NewGaugeMD(sysCPULoadPerc, "CPU load average 1min (percentage)")
	sysCPUNiceMD      = NewGaugeMD(sysCPUNice, "CPU nice time")