// EventNotifier - notifies external systems about events in MinIO.
type EventNotifier struct {
	sync.RWMutex
	targetList     *event.TargetList
	bucketRulesMap map[string]event.RulesMap
}

// NewEventNotifier - creates new event notification object.
func NewEventNotifier(ctx context.Context) *EventNotifier {
	// targetList/bucketRulesMap/bucketRemoteTargetRulesMap are populated by NotificationSys.InitBucketTargets()
	return &EventNotifier{

	// If a mux id is specified that mux is pinged.
	// Clients send ping requests.
	OpPing

	// OpPong is a OpPing response returned by the server.
	OpPong

	// OpConnectMux will connect a new mux with optional payload.
	OpConnectMux

	// OpMuxConnectError is an  error while connecting a mux.
	OpMuxConnectError

	// OpDisconnectClientMux instructs a client to disconnect a mux
	OpDisconnectClientMux

//     affects read from source, block, file, dedup, and object storage backup targets for a specific Veeam Job. When customers
//     create a new backup job and select the object storage or a SOBR as a backup target with this setting, the job default
//     setting will be set to this value. This setting will be only applied to newly created jobs (manual changes with Active Full

		return
	}
	m.recvMu.Lock()
	defer m.recvMu.Unlock()
	if m.outBlock == nil {
		// Closed
		return
	}
	select {
	case m.outBlock <- struct{}{}:
	default:
		gridLogIf(m.ctx, errors.New("output unblocked overflow"))
	}
}

func (m *muxServer) ping(seq uint32) pongMsg {
	if !m.checkSeq(seq) {
		msg := fmt.Sprintf("receive sequence number mismatch. want %d, got %d", m.RecvSeq, seq)

	}
	if len(extKey) != 32 { // safety check
		logger.CriticalIf(context.Background(), errors.New("crypto: invalid key length"))
	}
	var nonce [32]byte
	if _, err := io.ReadFull(random, nonce[:]); err != nil {
		logger.CriticalIf(context.Background(), errOutOfEntropy)
	}

	const Context = "object-encryption-key generation"
	mac := hmac.New(sha256.New, extKey)
	mac.Write([]byte(Context))
	mac.Write(nonce[:])
	mac.Sum(key[:0])
	return key

	v := strings.SplitN(s, ":", 2)
	if len(v) != 2 {
		return nil, errors.New("kms: invalid secret key format")
	}

	keyID, b64Key := v[0], v[1]
	key, err := base64.StdEncoding.DecodeString(b64Key)
	if err != nil {
		return nil, err
	}
	return NewBuiltin(keyID, key)
}

// NewBuiltin returns a single-key KMS that derives new DEKs from the
// given key.
func NewBuiltin(keyID string, key []byte) (*KMS, error) {

// BytePoolCap implements a leaky pool of []byte in the form of a bounded channel.
type BytePoolCap struct {
	c    chan []byte
	w    int
	wcap int
}

// NewBytePoolCap creates a new BytePool bounded to the given maxSize, with new
// byte arrays sized based on width.
func NewBytePoolCap(maxSize uint64, width int, capwidth int) (bp *BytePoolCap) {
	if capwidth > 0 && capwidth < 64 {

	"github.com/smallnest/ringbuffer"
)

func main() {
	rb := ringbuffer.New(1024)

	// write
	rb.Write([]byte("abcd"))
	fmt.Println(rb.Length())
	fmt.Println(rb.Free())

	// read
	buf := make([]byte, 4)
	rb.Read(buf)
	fmt.Println(string(buf))
}
```

It is possible to use an existing buffer with by replacing `New` with `NewBuffer`.


# Blocking vs Non-blocking

	for {
		stream, err := sr.NextStream()
		if err != nil {
			if err == io.EOF {
				if extracted {
					return nil
				}
				return errors.New("no data found on stream")
			}
			if errors.Is(err, estream.ErrNoKey) {
				if stream.Name == "inspect.zip" {
					return errors.New("incorrect private key")
				}
				if err := stream.Skip(); err != nil {
					return fmt.Errorf("stream skip: %w", err)
				}
				continue
			}

	}

	return rulesCopy
}

// Union - returns union with given rules as new rules.
func (rules Rules) Union(rules2 Rules) Rules {
	nrules := rules.Clone()

	for pattern, targetIDSet := range rules2 {
		nrules[pattern] = nrules[pattern].Union(targetIDSet)
	}

	return nrules
}

// Difference - returns difference with given rules as new rules.
func (rules Rules) Difference(rules2 Rules) Rules {
	nrules := make(Rules)