const (
	// minBufferSize is the minimum buffer size.
	// 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

package cmd

import (
	"context"
)

const (
	memTotal     = "total"
	memUsed      = "used"
	memFree      = "free"
	memBuffers   = "buffers"
	memCache     = "cache"
	memUsedPerc  = "used_perc"
	memShared    = "shared"
	memAvailable = "available"
)

var (
	memTotalMD     = NewGaugeMD(memTotal, "Total memory on the node")

	go func() {
		for {
			rb.Read(buf)
		}
	}()

	for b.Loop() {
		rb.Write(data)
	}
}

func BenchmarkRingBuffer_AsyncReadBlocking(b *testing.B) {
	const sz = 512
	const buffers = 10
	rb := New(sz * buffers)
	rb.SetBlocking(true)
	data := []byte(strings.Repeat("a", sz))
	buf := make([]byte, sz)

	go func() {
		for {
			rb.Read(buf)
		}
	}()

	for b.Loop() {
		rb.Write(data)
	}

	if uint64(len(bp.c)) != size {
		t.Fatalf("bytepool size invalid: got %v want %v", len(bp.c), size)
	}

	// lets drain the buf channel first before we validate invalid buffers.
	for range size {
		bp.Get() // discard
	}

	// Try putting some invalid buffers into pool
	bp.Put(make([]byte, bp.w, bp.wcap-1)) // wrong capacity is rejected (less)
	bp.Put(make([]byte, bp.w, bp.wcap+1)) // wrong capacity is rejected (more)

			if p.buf[bufIdx] == nil {
				// Reading first time on this disk, hence the buffer needs to be allocated.
				// Subsequent reads will reuse this buffer.
				p.buf[bufIdx] = make([]byte, p.shardSize)
			}
			// For the last shard, the shardsize might be less than previous shard sizes.
			// Hence the following statement ensures that the buffer size is reset to the right size.
			p.buf[bufIdx] = p.buf[bufIdx][:p.shardSize]

			// with dead end because tcp-keepalive is not fired when there is data in the socket buffer.
			//    https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/
			// This is a sensitive configuration, it is better to set it to high values, > 60 secs since it can
			// affect clients reading data with a very slow pace  (disappropriate with socket buffer sizes)
			if opts.UserTimeout > 0 {

		n2, e2 := io.ReadFull(r2, b2)
		if n1 != n2 {
			return false, fmt.Sprintf("Read %d != %d bytes from the readers", n1, n2)
		}
		if !bytes.Equal(b1[:n1], b2[:n2]) {
			return false, fmt.Sprintf("After reading %d equal buffers (32Kib each), we got the following two strings:\n%v\n%v\n",
				i, b1, b2)
		}
		// Check if stream has ended
		if (e1 == io.ErrUnexpectedEOF && e2 == io.ErrUnexpectedEOF) || (e1 == io.EOF && e2 == io.EOF) {
			break

		memUsedPerc:       "Used memory percentage on the node",
		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",

| `minio_node_mem_available_max` | Available memory on the node (max).       |
| `minio_node_mem_buffers`       | Buffers memory on the node.               |
| `minio_node_mem_buffers_avg`   | Buffers memory on the node (avg).         |
| `minio_node_mem_buffers_max`   | Buffers memory on the node (max).         |
| `minio_node_mem_cache`         | Cache memory on the node.                 |

	b.n = 0
	return nil
}

// Available returns how many bytes are unused in the buffer.
func (b *Writer) Available() int { return len(b.buf) - b.n }

// AvailableBuffer returns an empty buffer with b.Available() capacity.
// This buffer is intended to be appended to and
// passed to an immediately succeeding [Writer.Write] call.
// The buffer is only valid until the next write operation on b.
func (b *Writer) AvailableBuffer() []byte {