for i := 0; i < n; i++ {
					if i < n/2 {
						tab.Enqueue(&u[0])
					} else {
						tab.Enqueue(&u[SemTableSize])
					}
				}
				for i := 0; i < n; i++ {
					var ok bool
					if i < n/2 {
						ok = tab.Dequeue(&u[0])
					} else {
						ok = tab.Dequeue(&u[SemTableSize])
					}
					if !ok {
						b.Fatal("failed to dequeue")
					}
				}
			}
		})

	arrival := []*request{{}, {}, {}, {}, {}, {}}

	list := newRequestFIFO()
	for i := range arrival {
		list.Enqueue(arrival[i])
	}

	dequeued := make([]*request, 0)
	for list.Length() > 0 {
		req, _ := list.Dequeue()
		dequeued = append(dequeued, req)
	}

	verifyOrder(t, arrival, dequeued)
}

func TestFIFOWithEnqueueDequeueSomeRequestsRemainInQueue(t *testing.T) {
	list := newRequestFIFO()

		t.Parallel()
		p := NewPushQueue()
		defer p.ShutDown()
		p.Enqueue(proxies[0], &model.PushRequest{})
		p.Enqueue(proxies[1], &model.PushRequest{})

		ExpectDequeue(t, p, proxies[0])
		ExpectDequeue(t, p, proxies[1])
	})

	t.Run("remove too many", func(t *testing.T) {
		t.Parallel()
		p := NewPushQueue()
		defer p.ShutDown()

		p.Enqueue(proxies[0], &model.PushRequest{})

		ExpectDequeue(t, p, proxies[0])

//
// This is implemented as a doubly-linked list queue of poolDequeues
// where each dequeue is double the size of the previous one. Once a
// dequeue fills up, this allocates a new one and only ever pushes to
// the latest dequeue. Pops happen from the other end of the list and
// once a dequeue is exhausted, it gets removed from the list.
type poolChain struct {

// is not safe for concurrent use by multiple goroutines.
type fifo interface {
	// Enqueue enqueues the specified request into the list and
	// returns a removeFromFIFOFunc function that can be used to remove the
	// request from the list
	Enqueue(*request) removeFromFIFOFunc

	// Dequeue pulls out the oldest request from the list.
	Dequeue() (*request, bool)

import "testing"

func TestQueue(t *testing.T) {
	// Zero valued queue should have 0 length and capacity.
	var q queue
	if n := q.len; n != 0 {
		t.Fatalf("empty queue has len %d; want 0", n)
	}
	if n := q.cap(); n != 0 {
		t.Fatalf("empty queue has cap %d; want 0", n)
	}

	// As we add elements, len should grow.
	N := 32
	for i := 0; i < N; i++ {
		q.enqueue(i)
		if n := q.len; n != i+1 {

	for len(p.queue) == 0 && !p.shuttingDown {
		p.cond.Wait()
	}

	if len(p.queue) == 0 {
		// We must be shutting down.
		return nil, nil, true
	}

	con = p.queue[0]
	// The underlying array will still exist, despite the slice changing, so the object may not GC without this
	// See https://github.com/grpc/grpc-go/issues/4758
	p.queue[0] = nil
	p.queue = p.queue[1:]

	q.head = 0
}

func (q *queue) enqueue(e any) {
	if q.len+1 > q.cap() {
		q.grow()
	}
	i := (q.head + q.len) % q.cap()
	q.elems[i] = e
	q.len++
}

func (q *queue) dequeue() (any, bool) {
	if q.len == 0 {
		return nil, false
	}
	e := q.elems[q.head]
	q.elems[q.head] = nil
	q.head = (q.head + 1) % q.cap()
	q.len--
	return e, true
}

func (q *queue) peek() (any, bool) {
	if q.len == 0 {

			d := make(chan bool)
			a = append(a, d)
			go func() {
				for j := 0; j < messages; j++ {
					// queue ourselves on the global channel
					select {
					case <-c:
					case <-d:
					}
				}
			}()
		}
		for i := 0; i < messages; i++ {
			// wake each goroutine up, forcing it to dequeue and then enqueue
			// on the global channel.
			for _, d := range a {
				d <- true
			}
		}
	})

			if s.parent.next != s {
				panic("semaRoot queue")
			}
			root.rotateLeft(s.parent)
		}
	}
}

// dequeue searches for and finds the first goroutine
// in semaRoot blocked on addr.
// If the sudog was being profiled, dequeue returns the time
// at which it was woken up as now. Otherwise now is 0.
// If there are additional entries in the wait list, dequeue
// returns tailtime set to the last entry's acquiretime.