input        chan *queueItem  // input for workers
	queue        chan *queueItem  // output from workers in order
	err          error            // global error state, only touched by Reader.Read
	bufferPool   sync.Pool        // pool of []byte objects for input
	csvDstPool   sync.Pool        // pool of [][]string used for output

	"github.com/minio/minio/internal/logger"
	"github.com/minio/minio/internal/mcontext"
)

type apiConfig struct {
	mu sync.RWMutex

	requestsDeadline time.Duration
	requestsPool     chan struct{}
	clusterDeadline  time.Duration
	listQuorum       string
	corsAllowOrigins []string
	// total drives per erasure set across pools.
	totalDriveCount       int
	replicationPriority   string

	saver := z.serverPools[o.pool].sets[o.set]

	// Disconnect from call above, but cancel on exit.
	listCtx, cancel := context.WithCancel(GlobalContext)
	saveCh := make(chan metaCacheEntry, metacacheBlockSize)
	inCh := make(chan metaCacheEntry, metacacheBlockSize)
	outCh := make(chan metaCacheEntry, o.Limit)

	filteredResults := o.gatherResults(ctx, outCh)

	mc := o.newMetacache()

	opts      madmin.HealOpts
	// Healing response will be sent here
	respCh chan healResult
}

// healResult represents a healing result with a possible error
type healResult struct {
	result madmin.HealResultItem
	err    error
}

// healRoutine receives heal tasks, to heal buckets, objects and format.json
type healRoutine struct {
	tasks   chan healTask
	workers int
}

func activeListeners() int {

	mrfMU      sync.Mutex
	resyncer   *replicationResyncer

	// workers:
	workers    []chan ReplicationWorkerOperation
	lrgworkers []chan ReplicationWorkerOperation

	// mrf:
	mrfWorkerKillCh chan struct{}
	mrfReplicaCh    chan ReplicationWorkerOperation
	mrfSaveCh       chan MRFReplicateEntry
	mrfStopCh       chan struct{}
	mrfWorkerSize   int
}

	if handler == nil {
		return nil, ErrUnknownHandler
	}

	var requests chan []byte
	var responses chan Response
	if handler.InCapacity > 0 {
		requests = make(chan []byte, handler.InCapacity)
	}
	if handler.OutCapacity > 0 {
		responses = make(chan Response, handler.OutCapacity)
	} else {
		responses = make(chan Response, 1)
	}

	cl, err := c.newMuxClient(ctx)
	if err != nil {

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)