sluice/dispatcher

A dispatcher decides which subscriber of a producer stage receives which events. Set the dispatcher of a source or a gate with the dispatcher builder function of the stage. The default is demand.

Types

Dispatcher

opaque </>

A dispatcher for a producer stage. Each start of a stage receives a new, empty instance.

pub opaque type Dispatcher(event)

Values

broadcast

</>

pub fn broadcast() -> Dispatcher(event)

Each event goes to each subscriber. The flow moves at the speed of the slowest subscriber. A subscriber can set a filter on its subscription with sluice.selector. It then receives only the events that the filter keeps. A new subscriber stops the flow until it asks.

demand

</>

pub fn demand() -> Dispatcher(event)

The default dispatcher. Events go to the subscriber with the largest open demand. Thus, with time, the load becomes equal across the subscribers. Each event goes to exactly one subscriber.

partition

</>

pub fn partition(
  count count: Int,
  by by: fn(event) -> Int,
) -> Dispatcher(event)

The by function gives each event a partition from 0 to count - 1, and each event goes to the subscriber of its partition. Each partition accepts a maximum of one subscriber. A subscriber selects its partition with sluice.partition. Events for a partition without open demand wait in a queue for that partition. Thus a slow partition does not stop the other partitions.

count: The quantity of partitions.
by: The function that gives one event its partition, from 0 to count - 1.