type Cache[T any] struct {
	// updateFn must return an updated value.
	// If an error is returned the cached value is not set.
	// Only one caller will call this function at any time, others will be blocking.
	// The returned value can no longer be modified once returned.
	// Should be set before calling Get().
	updateFn func(ctx context.Context) (T, error)

	// ttl for a cached value.
	ttl time.Duration

	opts Opts

	types          uint64
	numSubscribers int32
	maxSubscribers int32

	// not atomics:
	subs []*Sub[T]
	sync.RWMutex
}

// Publish message to the subscribers.
// Note that publish is always non-blocking send so that we don't block on slow receivers.
// Hence receivers should use buffered channel so as not to miss the published events.
func (ps *PubSub[T, M]) Publish(item T) {
	ps.RLock()
	defer ps.RUnlock()

    }
    CyclicBarrier barrier =
        new CyclicBarrier(
            6 // for the setter threads
                + 50 // for the listeners
                + 50 // for the blocking get threads,
                + 1); // for the main thread
    ExecutorService executor = newFixedThreadPool(barrier.getParties());
    AtomicReference<AbstractFuture<String>> currentFuture = Atomics.newReference();

 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost
 *     a race in fast follow-up.
 *
 *  4. If there's no existing connection, make a list of routes (which may require blocking DNS
 *     lookups) and attempt new connections to them. When failures occur, retries iterate the
 *     list of available routes.
 *

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Queue;

/**
 * A non-blocking queue which automatically evicts elements from the head of the queue when
 * attempting to add new elements onto the queue and it is full. This queue orders elements FIFO

   *
   * <p>Currently, this method is invoked while holding a lock. If an implementation of this method
   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and
   * implementing {@code stopping}. Note, however, that {@code stopping} does not run at exactly the

  // TODO: Test getQueueLength().
  // TODO: Test hasQueuedThreads().
  // TODO: Test getWaitQueueLength(Guard).
  // TODO: Test automatic signaling before leave, waitFor, and reentrant enterWhen.
  // TODO: Test blocking to re-enter monitor after being signaled.
  // TODO: Test interrupts with both interruptible and uninterruptible monitor.
  // TODO: Test multiple waiters: If guard is still satisfied, signal next waiter.

    Define it as a *path operation function* (or dependency) parameter.

    If you are using a regular `def` function, you can use the `upload_file.file`
    attribute to access the raw standard Python file (blocking, not async), useful and
    needed for non-async code.

    Read more about it in the
    [FastAPI docs for Request Files](https://fastapi.tiangolo.com/tutorial/request-files/).

    ## Example

    ```python

            final int flags = oldFlags | ServerMessageBlock2.SMB2_FLAGS_SIGNED;
            SMBUtil.writeInt4(flags, data, offset + 16);

            // Create new Mac instance for thread safety without blocking other operations
            Mac mac;
            try {
                mac = createMacInstance();
            } catch (GeneralSecurityException e) {

     *   available.
     * 3. We expect the client's get() to throw an InterruptedException.
     * 4. We expect the client thread's interrupt state to be false.
     * 5. The client thread again makes a blocking call to get().
     * 6. Now the result becomes available.
     * 7. We expect get() to return this result.
     * 8. We expect the test thread's interrupt state to be false.
     */