eventlist

An eventlist is a data structure used to store events scheduled for future processing. In discrete-event simulation, it functions as a priority queue ordered by event time, ensuring that the earliest event is retrieved first. In event-driven systems, it may serve as a queue of pending tasks or timers that the system will handle in due course.

Core features include insertion of new events with associated time or priority, retrieval of the next event, and optional removal of events. Depending on implementation, additional operations such as peeking at the next event, finding or canceling an event, and iterating through scheduled events are supported.

Common implementations are priority queues (min-heaps) which give O(log n) insertion and removal, and sorted linked lists which allow O(1) access to the first element but O(n) insertion. The choice depends on workload characteristics.

Typical event records contain at least a time stamp, an event type or identifier, and an optional payload or handler/callback to be invoked when the event is processed.

Use cases include discrete-event simulations (manufacturing, networks, traffic), user interface and operating system event loops, game and real-time systems, and workflow scheduling.

While the term "eventlist" is used in some libraries and papers, it is often synonymous with a priority queue or event queue. In practice, keeping the list ordered by time facilitates determinism in simulations and timely handling of timed tasks.