Subscription¶

A Subscription represents a one-to-one lifecycle of a Subscriber subscribing to a Publisher.

It can only be used by a single Subscriber.

It is used to both signal desire for data and cancel demand (and allow resource cleanup).

interface ref Subscription

Public Functions¶

No events will be sent by a Publisher until demand is signaled via this method.

It can be called however often and whenever needed—but the outstanding cumulative demand must never exceed U64.max_value.

An outstanding cumulative demand of U64.max_value may be treated by the Publisher as "effectively unbounded".

Whatever has been requested can be sent by the Publisher so only signal demand for what can be safely handled.

A Publisher can send less than is requested if the stream ends but then must emit either Subscriber.on_error or Subscriber.on_complete.

fun ref request(
  n: U64 val)
: None val

Request the Publisher to stop sending data and clean up resources.

Data may still be sent to meet previously signalled demand after calling cancel as this request is asynchronous.

fun ref cancel()
: None val