// `.TnitOnce`.
func New[T any]() *Cache[T] {
	return &Cache[T]{}
}

// NewFromFunc allocates a new cached value instance and initializes it with an
// update function, making it ready for use.
func NewFromFunc[T any](ttl time.Duration, opts Opts, update func() (T, error)) *Cache[T] {
	return &Cache[T]{
		ttl:      ttl,
		updateFn: update,
		opts:     opts,
	}
}

	"istio.io/istio/pkg/maps"
	"istio.io/istio/pkg/zdsapi"
)

var ErrPodNotFound = errors.New("netns not provided, but is needed as pod is not in cache")

type PodNetnsCache interface {
	ReadCurrentPodSnapshot() map[string]WorkloadInfo
}

// Hold a cache of node local pods with their netns
// if we don't know the netns, the pod will still be here with a nil netns.
type podNetnsCache struct {

	workers *ActiveWorkerStat
	// queue stats cache
	qCache queueCache

	pCache proxyStatsCache
	// mrf backlog stats
	mrfStats ReplicationMRFStats
	// for bucket replication, continue to use existing cache
	Cache             map[string]*BucketReplicationStats
	mostRecentStats   BucketStatsMap
	registry          metrics.Registry
	sync.RWMutex                 // mutex for Cache
	mostRecentStatsMu sync.Mutex // mutex for mostRecentStats

	Sleep   time.Duration `json:"sleep"`
	IOCount int           `json:"iocount"`

	DriveWorkers int `json:"drive_workers"`

	// Cached value from Bitrot field
	cache struct {
		// -1: bitrot enabled, 0: bitrot disabled, > 0: bitrot cycle
		bitrotCycle time.Duration
	}
}

// BitrotScanCycle returns the configured cycle for the scanner healing
// -1 for not enabled
//

// it returns true if there is no tags in the underlying Filter.
func (f Filter) TestTags(userTags string) bool {
	if f.cachedTags == nil {
		cache := make(map[string]string)
		for _, t := range append(f.And.Tags, f.Tag) {
			if !t.IsEmpty() {
				cache[t.Key] = t.Value
			}
		}
		f.cachedTags = cache
	}

	// This filter does not have any tags, always return true
	if len(f.cachedTags) == 0 {
		return true
	}

	"sigs.k8s.io/controller-runtime/pkg/client/interceptor"
	"sigs.k8s.io/controller-runtime/pkg/envtest"

	"istio.io/istio/istioctl/pkg/cli"
	"istio.io/istio/operator/pkg/apis/istio/v1alpha1"
	"istio.io/istio/operator/pkg/cache"
	"istio.io/istio/operator/pkg/helmreconciler"
	"istio.io/istio/operator/pkg/manifest"
	"istio.io/istio/operator/pkg/name"
	"istio.io/istio/operator/pkg/object"
	"istio.io/istio/operator/pkg/util/clog"

		if len(dui.BucketsUsage) > 0 {
			internalLogOnceIf(GlobalContext, fmt.Errorf("unable to retrieve usage information for bucket: %s, relying on older value cached in-memory: err(%v)", bucket, err), "bucket-usage-cache-"+bucket)
		} else {
			internalLogOnceIf(GlobalContext, errors.New("unable to retrieve usage information for bucket: %s, no reliable usage value available - quota will not be enforced"), "bucket-usage-empty-"+bucket)
		}
	}

		memFree:           "Free memory on the node",
		memShared:         "Shared memory on the node",
		memBuffers:        "Buffers memory on the node",
		memCache:          "Cache memory on the node",
		memAvailable:      "Available memory on the node",
		readsPerSec:       "Reads per second on a drive",
		writesPerSec:      "Writes per second on a drive",

	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = src.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return *(*string)(unsafe.Pointer(&b))
}

}

// LookupConfig - lookup api config and override with valid environment settings if any.
func LookupConfig(kvs config.KVS) (cfg Config, err error) {
	deprecatedKeys := []string{
		apiReadyDeadline,
		"extend_list_cache_life",
		apiReplicationWorkers,
		apiReplicationFailedWorkers,
		"expiry_workers",
	}

	disableODirect := env.Get(EnvAPIDisableODirect, kvs.Get(apiDisableODirect)) == config.EnableOn