This allows the dynamic creation of an Outlet for a GraphStage which is connected to a Source that is available for materialization (e.g. using the subFusingMaterializer). Completion, cancellation and failure of the parent operator is automatically delegated to instances of SubSourceOutlet to avoid resource leaks.
Even so it is good practice to use the timeout method to cancel this Outlet in case the corresponding Source is not materialized within a given time limit, see e.g. ActorMaterializerSettings.
To be thread safe this method must only be called from either the constructor of the graph operator during materialization or one of the methods invoked by the graph operator machinery, such as onPush and onPull.
Returns true if this output port is closed, but caution THIS WORKS DIFFERENTLY THAN THE NORMAL isClosed(out). Due to possibly asynchronous shutdown it may not return true immediately after complete() or fail() have returned.
Returns true if this output port is closed, but caution THIS WORKS DIFFERENTLY THAN THE NORMAL isClosed(out). Due to possibly asynchronous shutdown it may not return true immediately after complete() or fail() have returned.