pharos/event_bus

The alert event bus.

A thin, restart-resilient wrapper around an eparch/event_manager configured with a registered name. The wrapper holds the Name, not a Pid or Manager value, so handles stay valid across supervisor restarts: when the underlying gen_event process is restarted under the same registered name, every previously-issued EventBus handle keeps working transparently.

Most callers should not interact with EventBus directly: it is constructed by the pharos supervisor and exposed indirectly via pharos.subscribe / pharos.unsubscribe.

Types

EventBus

opaque </>

Restart-resilient handle to a running alert event bus.

pub opaque type EventBus

HandlerId

opaque </>

Opaque reference to a registered handler. Returned by add_handler/2; pass to remove_handler/2 to unsubscribe. The bus only registers fire-and-forget handlers, so the request/reply type parameters are both Nil.

pub opaque type HandlerId

Values

add_handler

</>

pub fn add_handler(
  bus: EventBus,
  handler: fn(alert.AlertEvent) -> Nil,
) -> Result(HandlerId, event_manager.AddError(Nil, Nil))

from_name

</>

pub fn from_name(
  name: process.Name(alert.AlertEvent),
) -> EventBus

Wrap a registered name as an EventBus. The name must already (or eventually) be registered to a running gen_event manager process; the wrapper resolves it lazily on every API call.

notify

</>

pub fn notify(bus: EventBus, event: alert.AlertEvent) -> Nil

Broadcast event to every registered handler. Non-blocking.

remove_handler

</>

pub fn remove_handler(
  bus: EventBus,
  id: HandlerId,
) -> Result(Nil, event_manager.RemoveError(Nil, Nil))

Unregister a previously added handler.

start_link

</>

pub fn start_link(
  name: process.Name(alert.AlertEvent),
) -> Result(#(process.Pid, EventBus), event_manager.StartError)

Start a fresh event bus registered under name.

Used by the supervisor’s bus child. The returned Pid is the bus’s process id (suitable for actor.Started); the bus is also registered under name so other processes can reach it after a restart.