WithCleanupThresholdCount defines the count of deletions that triggers shrinking of the map.

WithCleanupThresholdRatio defines the ratio between the amount of deleted keys and the current map's size before shrinking is triggered.

WithMaxTopicSubscriptionsPerClient defines the max amount of subscriptions per client before the client is seen as malicious and gets dropped.

Events contains all the events that are triggered by the SubscriptionManager.

SubscriptionManager keeps track of subscribed topics of clients.