// dataUsageCacheV2 contains a cache of data usage entries version 2.
type dataUsageCacheV2 struct {
	Info  dataUsageCacheInfo
	Cache map[string]dataUsageEntryV2
}

// dataUsageCacheV3 contains a cache of data usage entries version 3.
type dataUsageCacheV3 struct {
	Info  dataUsageCacheInfo
	Cache map[string]dataUsageEntryV3
}

// dataUsageCacheV4 contains a cache of data usage entries version 4.

					return
				default:
				}

				// Load cache for bucket
				cacheName := pathJoin(bucket.Name, dataUsageCacheName)
				cache := dataUsageCache{}
				scannerLogIf(ctx, cache.load(ctx, er, cacheName))
				if cache.Info.Name == "" {
					cache.Info.Name = bucket.Name
				}
				cache.Info.SkipHealing = healing
				cache.Info.NextCycle = wantCycle
				if cache.Info.Name != bucket.Name {

}

// worthKeeping indicates if the cache by itself is worth keeping.
func (m *metacache) worthKeeping() bool {
	if m == nil {
		return false
	}
	cache := m
	switch {
	case !cache.finished() && time.Since(cache.lastUpdate) > metacacheMaxRunningAge:
		// Not finished and update for metacacheMaxRunningAge, discard it.
		return false
	case cache.finished() && time.Since(cache.lastHandout) > 5*metacacheMaxClientWait:

	EnvKESServerCA         = "MINIO_KMS_KES_CAPATH"         // Path to file/directory containing CA certificates to verify the KES server certificate
	EnvKESKeyCacheInterval = "MINIO_KMS_KEY_CACHE_INTERVAL" // Period between polls of the KES KMS Master Key cache, to prevent it from being unused and purged

	// Create indicates that the lister should not attempt to load an existing cache.
	Create bool

	// Include pure directories.
	IncludeDirectories bool

	// Transient is set if the cache is transient due to an error or being a reserved bucket.
	// This means the cache metadata will not be persisted on disk.
	// A transient result will never be returned from the cache so knowing the list id is required.
	Transient bool

	processIOReadBytesMD              = NewCounterMD(processIOReadBytes, "Total bytes read by the process from the underlying storage system, /proc/[pid]/io read_bytes")
	processIOWCharBytesMD             = NewCounterMD(processIOWCharBytes, "Total bytes written by the process to the underlying storage system including page cache, /proc/[pid]/io wchar")

	DiskID string
}

// supported FS for Nlink optimization in readdir.
const (
	xfs  = "XFS"
	ext4 = "EXT4"
)

// WalkDir will traverse a directory and return all entries found.
// On success a sorted meta cache stream will be returned.
// Metadata has data stripped, if any.
func (s *xlStorage) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
	legacyFS := !(s.fsType == xfs || s.fsType == ext4)

	s.RLock()

	// returns 'nil' once healing is complete or if the disk
	// has never been replaced.
	Healing() *healingTracker
	DiskInfo(ctx context.Context, opts DiskInfoOptions) (info DiskInfo, err error)
	NSScanner(ctx context.Context, cache dataUsageCache, updates chan<- dataUsageEntry, scanMode madmin.HealScanMode, shouldSleep func() bool) (dataUsageCache, error)

	// Volume operations.
	MakeVol(ctx context.Context, volume string) (err error)

	return c, nil
}

// Request KES keep an up-to-date copy of the KMS master key to allow minio to start up even if KMS is down. The
// cached key may still be evicted if the period of this function is longer than that of KES .cache.expiry.unused
func (c *kesClient) refreshKMSMasterKeyCache(logger Logger) {
	ctx := context.Background()

	defaultCacheDuration := 10 * time.Second

		}
		erasureSet, ok := poolInfo[d.SetIndex]
		if !ok {
			erasureSet.ID = d.SetIndex
			cache := dataUsageCache{}
			if err := cache.load(ctx, z.serverPools[d.PoolIndex].sets[d.SetIndex], dataUsageCacheName); err == nil {
				dataUsageInfo := cache.dui(dataUsageRoot, nil)
				erasureSet.ObjectsCount = dataUsageInfo.ObjectsTotalCount
				erasureSet.VersionsCount = dataUsageInfo.VersionsTotalCount