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 {
		panic("buffer capped with smaller than 64 bytes is not supported")
	}

	// Buffers below this is not reused.
	minBufferSize = 1 << 10

	// defaultBufferSize is the default buffer allocation size.
	defaultBufferSize = 4 << 10

	// maxBufferSize is the maximum buffer size.
	// Buffers larger than this is not reused.
	maxBufferSize = 96 << 10

	// This is the assumed size of bigger buffers and allocation size.
	biggerBufMin = 32 << 10

	// This is the maximum size of bigger buffers.
	biggerBufMax = maxBufferSize

// Updates are sent on a regular basis and the caller *must* consume them.
func (er erasureObjects) nsScanner(ctx context.Context, buckets []BucketInfo, wantCycle uint32, updates chan<- dataUsageCache, healScanMode madmin.HealScanMode) error {
	if len(buckets) == 0 {
		return nil
	}

	// Collect disks we can use.
	disks, healing := er.getOnlineDisksWithHealing(false)
	if len(disks) == 0 {

	// 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)

	desc *prometheus.Desc
}

// Describe sends the super-set of all possible descriptors of metrics
func (c *minioCollector) Describe(ch chan<- *prometheus.Desc) {
	ch <- c.desc
}

// Collect is called by the Prometheus registry when collecting metrics.
func (c *minioCollector) Collect(ch chan<- prometheus.Metric) {
	// Expose MinIO's version information
	minioVersionInfo.WithLabelValues(Version, CommitID).Set(1.0)

	// Use buffered channel to take care of burst sends or slow w.Write()
	mergeCh := make(chan []byte, globalAPIConfig.getRequestsPoolCapacity()*len(globalEndpoints.Hostnames()))
	localCh := make(chan event.Event, globalAPIConfig.getRequestsPoolCapacity())

	// Convert local messages to JSON and send to mergeCh
	go func() {

	defer n.Unlock()
	n.RX = 0
	n.RXSample = 0
	n.lastToConnect = time.Time{}
	n.firstToDisconnect = time.Time{}
}

// Reader to read random data.
type netperfReader struct {
	n   uint64
	eof chan struct{}
	buf []byte
}

func (m *netperfReader) Read(b []byte) (int, error) {
	select {
	case <-m.eof:
		return 0, io.EOF
	default:
	}
	n := copy(b, m.buf)
	atomic.AddUint64(&m.n, uint64(n))

	es := &expiryState{
		ctx:    ctx,
		objAPI: objAPI,
	}
	workers := make([]chan expiryOp, 0, n)
	es.workers.Store(&workers)
	es.ResizeWorkers(n)
	return es
}

func (es *expiryState) getWorkerCh(h uint64) chan<- expiryOp {
	w := es.workers.Load()
	if w == nil || len(*w) == 0 {
		return nil
	}
	workers := *w

	name := newTgt.Name()

	currentBuff, ok := logChBuffers[name]
	if !ok {
		logChBuffers[name] = make(chan interface{}, requiredCap)
		currentCap = requiredCap
	} else {
		currentCap = cap(currentBuff)
		requiredCap += len(currentBuff)
	}

	if requiredCap > currentCap {
		logChBuffers[name] = make(chan interface{}, requiredCap)

		if len(currentBuff) > 0 {
		drain:
			for {
				select {

	// All responses *must* be read by the caller until either an error is returned or the channel is closed.
	// Canceling the context will cause the context cancellation error to be returned.
	responses <-chan Response
	cancel    context.CancelCauseFunc

	// Requests sent to the server.
	// If the handler is defined with 0 incoming capacity this will be nil.
	// Channel *must* be closed to signal the end of the stream.