EventBus

EventBus<Event, Policy> is the generic publish/subscribe queue used throughout Flox. It coordinates fan-out of events to multiple listeners with minimal overhead.

Definition

template <typename Event, typename Policy>
class EventBus {
public:
  using Listener = typename ListenerType<Event>::type;
  using Queue = SPSCQueue<typename Policy::QueueItem, 4096>;

  void subscribe(std::shared_ptr<Listener> listener);
  void start();
  void stop();

  void publish(Event ev);
  Queue* getQueue(SubscriberId id);
  uint64_t currentTickId() const;
};

Policies

• AsyncPolicy – dispatch without waiting. Each event is queued for every subscriber.
• SyncPolicy – uses a TickBarrier so the publisher waits until all subscribers finish processing.

Subscriber Modes

• PUSH – bus spawns a worker thread and pushes events to the listener.
• PULL – listener calls getQueue() and processes events manually.

Notes

• Every published event receives an incrementing tick sequence number.
• Specialized buses (BookUpdateBus, TradeBus, CandleBus, OrderExecutionBus) are typedefs of EventBus with concrete event types.