}

// EncryptMultiPart encrypts an io.Reader which must be the body of
// multi-part PUT request. It derives an unique encryption key from
// the partID and the object key.
func EncryptMultiPart(r io.Reader, partID int, key ObjectKey) io.Reader {
	partKey := key.DerivePartKey(uint32(partID))
	return EncryptSinglePart(r, ObjectKey(partKey))
}

// DecryptSinglePart decrypts an io.Writer which must an object

	// within the hour since l.UpdatedAt
	if since < 1 {
		return
	}

	idx, lastIdx := t.Hour(), l.UpdatedAt.Hour()

	l.UpdatedAt = t // update to the latest time index

	if since >= 24 {
		l.Bins = [24]tierStats{}
		return
	}

	for lastIdx != idx {
		lastIdx = (lastIdx + 1) % 24
		l.Bins[lastIdx] = tierStats{}
	}
}

func (l *lastDayTierStats) clone() lastDayTierStats {

	m.Set(driveWaitingIO, float64(disk.Metrics.TotalWaiting), labels...)

	// Append the api label for the drive API latencies.
	labels = append(labels, "api", "")
	lastIdx := len(labels) - 1
	for apiName, latency := range disk.Metrics.LastMinute {
		labels[lastIdx] = "storage." + apiName
		m.Set(driveAPILatencyMicros, float64(latency.Avg().Microseconds()),
			labels...)
	}
}

	}
}

var derivePartKeyTest = []struct {
	PartID  uint32
	PartKey string
}{
	{PartID: 0, PartKey: "aa7855e13839dd767cd5da7c1ff5036540c9264b7a803029315e55375287b4af"},
	{PartID: 1, PartKey: "a3e7181c6eed030fd52f79537c56c4d07da92e56d374ff1dd2043350785b37d8"},
	{PartID: 10000, PartKey: "f86e65c396ed52d204ee44bd1a0bbd86eb8b01b7354e67a3b3ae0e34dd5bd115"},
}