Reactor lifecycle

Every reactor goes through a certain set of stages during its lifetime, which are jointly called a reactor lifecycle. When the reactor enters a specific stage, it emits a lifecycle event. These lifecycle events are dispatched on a special daemon event stream called sysEvents. Every reactor is created with this special event stream.

The reactor lifecycle can be summarized as follows:

• After calling the spawn method, the reactor is scheduled for execution. Its constructor is started asynchronously, and immediately after that, a ReactorStarted event is dispatched.

• Then, whenever the reactor gets execution time, the ReactorScheduled event gets dispatched. After that, events get dispatched on normal event streams.

• When the scheduling system decides to pre-empt the reactor, the ReactorPreempted event is dispatched. This scheduling cycle can be repeated any number of times.

• Eventually, the reactor terminates, either by normal execution or exceptionally. If a user code exception terminates...