feat: support dispatching the runtime events

[nyannyacha]

What kind of change does this PR introduce?

Feature, Enhancement

Description

This PR adds support for event dispatching for the user worker lifecycle.

Type of events supported

• load
  • It is triggered when the script is loaded and all TLA (Top level await) are resolved
• beforeunload
  • It is triggered when the resource limit reaches a certain threshold (default value 90%).
  • It is recorded in detail.reason property as to which resource limiter triggered this event.

The threshold for the beforeunload event can be set through the CLI, and the list of flags is as follows:

• dispatch-beforeunload-wall-clock-ratio (max: 99, default value: 90)
• dispatch-beforeunload-cpu-ratio (max: 99, default value: 90)
• dispatch-beforeunload-memory-ratio (max: 99, default value: 90)

The unload event

This event is not triggered at the moment because the trigger point is ambiguous.

Currently, when the resource reaches the limit, the worker is forcibly terminated by the supervisor, so there is no margin to trigger the unload event. To trigger this event, it is necessary to first clarify the point at which it will be triggered.

Sample (beforeunload)

addEventListener("beforeunload", (ev) => {
    console.log(ev);
});

export default {
    fetch() {
        return new Response("meow");
    }
}

Output

// console.log(ev);
CustomEvent {
  bubbles: false,
  cancelable: true,
  composed: false,
  currentTarget: Window {},
  defaultPrevented: false,
  eventPhase: 2,
  srcElement: null,
  target: Window {},
  returnValue: true,
  timeStamp: 0,
  type: "beforeunload",
  detail: { reason: "wall_clock" }
}

[github-actions]

🎉 This PR is included in version 1.63.0 🎉

The release is available on GitHub release

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