*
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.
 *   <li>for nested locking, the cost increases with the depth of the nesting:
 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()
 *         <li>4 levels: average of 99ns per lock()/unlock()

			defer close(lk2ch)
			nsLk.lock(ctx, "volume", "path", "source", "opsID", false, 1*time.Millisecond)
		}()
		time.Sleep(1 * time.Millisecond) // wait for goroutine to advance; ref=2

		// Unlock the 1st lock; ref=1 after this line
		nsLk.unlock("volume", "path", false)

		// Taking another lockMapMutex here allows queuing up additional lockers. This should
		// not be required but makes reproduction much easier.
		nsLk.lockMapMutex.Lock()

	t.lastDayMu.Lock()
	defer t.lastDayMu.Unlock()

	if _, ok := t.lastDayStats[tier]; !ok {
		t.lastDayStats[tier] = &lastDayTierStats{}
	}
	t.lastDayStats[tier].addStats(ts)
}

func (t *transitionState) getDailyAllTierStats() DailyAllTierStats {
	t.lastDayMu.RLock()
	defer t.lastDayMu.RUnlock()

	res := make(DailyAllTierStats, len(t.lastDayStats))

	} else {
		m.send(message{Op: OpDisconnectClientMux, MuxID: m.ID})
	}
	// Unlock, since we are calling deleteMux, which will call close - which will lock recvMu.
	if locked {
		m.recvMu.Unlock()
		defer m.recvMu.Lock()
	}
	m.parent.deleteMux(true, m.ID)
}

func (m *muxServer) send(msg message) {
	m.sendMu.Lock()
	defer m.sendMu.Unlock()
	msg.MuxID = m.ID
	msg.Seq = m.SendSeq
	m.SendSeq++
	if debugPrint {

	mu sync.Mutex
}

func (d *disconnectReader) Read(p []byte) (n int, err error) {
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.r != nil {
		return d.r.Read(p)
	}
	return 0, errors.New("reader closed")
}

func (d *disconnectReader) Close() error {
	d.mu.Lock()
	d.r = nil
	d.mu.Unlock()
	return nil
}

	if srv.listener == nil {
		srv.listenerMutex.Unlock()
		return http.ErrServerClosed
	}
	srv.listenerMutex.Unlock()

	if atomic.AddUint32(&srv.inShutdown, 1) > 1 {
		// shutdown in progress
		return http.ErrServerClosed
	}

	// Close underneath HTTP listener.
	srv.listenerMutex.Lock()
	err := srv.listener.Close()
	srv.listenerMutex.Unlock()
	if err != nil {
		return err
	}

 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.
 *   <li>for nested locking, the cost increases with the depth of the nesting:
 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()
 *         <li>4 levels: average of 99ns per lock()/unlock()

// IsClosed - Check if the rlocked file is already closed.
func (r *RLockedFile) IsClosed() bool {
	r.mutex.Lock()
	defer r.mutex.Unlock()
	return r.refs == 0
}

// IncLockRef - is used by called to indicate lock refs.
func (r *RLockedFile) IncLockRef() {
	r.mutex.Lock()
	r.refs++
	r.mutex.Unlock()
}

// Close - this closer implements a special closer
// closes the underlying fd only when the refs
// reach zero.

  }

  @Override
  public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
    return delegate().tryLock(time, unit);
  }

  @Override
  public void unlock() {
    delegate().unlock();
  }

  @Override
  public Condition newCondition() {
    return delegate().newCondition();
  }

	if err = rlk.Close(); err != os.ErrInvalid {
		t.Fatal(err)
	}

	_, err = newRLockedFile(nil)
	if err != os.ErrInvalid {
		t.Fatal("Unexpected error", err)
	}
}

// Tests lock and unlock semantics.
func TestLockAndUnlock(t *testing.T) {
	f, err := os.CreateTemp(t.TempDir(), "lock")
	if err != nil {
		t.Fatal(err)
	}
	f.Close()
	defer func() {
		err = os.Remove(f.Name())