A plugin method to detect when an event was flushed

[mattlennon3]

Summary

I'm trying to make a plugin which will update my store with the number events which are actually sent to Segment, ideally the count of successful uploads.

This plugin will be ran in our pre-release environment as part of an automation test suite, so we can ensure Segment events are being uploaded successfully before we release to production.

Here's the best I have come up with for now:

export class EventCounter extends Plugin {
  type = PluginType.after;

  execute(e: SegmentEvent) {

    // if (production), return e; else:

    useStore.setState(state => {
      return {
        ...state,
        e2eSegmentEventCount: state.e2eSegmentEventCount + 1,
      };
    });
    return e;
  }
}

This does work at the moment, but it's just counting processed events, not ones that have actually been sent.

Proposed Solution

Perhaps some kind of onFlushed event:

export class EventCounter extends Plugin {
  type = PluginType.after;

  // New event here:
  onFlushSuccess(e: SegmentEvent) {

    // if (production), return e; else:

    useStore.setState(state => {
      return {
        ...state,
        e2eSegmentEventCount: state.e2eSegmentEventCount + 1,
      };
    });
    return e;
  }
}

// Could even have:
// onFlushFailed

Once the event has passed through this plugin, it can be cleared from memory.

Thanks

[sunitaprajapati89]

@mattlennon3 : Thanks for sharing your approach.
Rather than adding custom lifecycle methods like onFlushSuccess to the plugin, I’d recommend taking inspiration from the CountFlushPolicy implementation. Segment's flush policies are designed to respond to event delivery thresholds, and CountFlushPolicy already tracks when a flush should occur based on the number of events.
You can use this as a reference to build your own mechanism that:

• Monitors flush behavior
• Triggers a callback when a flush is initiated or completed
• Updates your store accordingly

Let me know if you have further queries.