Metrics

nBridge can collect live traffic metrics in-process — no external agent, no network calls.

Enable

import { createBridge } from "nbridge";

const bridge = createBridge({
  metrics: {
    enabled: true,
    updateInterval: 1000,  // recompute + notify listeners every second
    detailedTiming: false, // per-message timing detail
  },
});

All three fields are required when you pass a metrics config. Defaults when omitted entirely: disabled.

Reading

const metrics = bridge.getMetrics();
// null when metrics are disabled, otherwise:
// {
//   messagesSent: 240,
//   messagesReceived: 236,
//   messagesFailed: 1,
//   timeouts: 3,
//   averageResponseTime: 42.7,     // ms, over correlated request/response pairs
//   successRate: 0.983,
//   messagesPerSecond: 3.2,
//   peakMessagesPerSecond: 18,
//   bytesSent: 51_200,             // wire size, after compression
//   bytesReceived: 48_930,
// }

Subscribing

const unsubscribe = bridge.onMetricsUpdate((metrics) => {
  statusBar.update(`${metrics.messagesPerSecond.toFixed(1)} msg/s`);
});

// later
unsubscribe();

Listeners fire every updateInterval milliseconds.

In React, useBridgeMetrics wraps this subscription in a hook.

What counts

• Sent / received are recorded at the adapter boundary, so bytesSent / bytesReceived reflect the actual wire size (post-compression, including batch envelopes).
• Timeouts increment whenever a pending response's deadline passes.
• Failed increments when the outgoing pipeline throws (adapter failure, middleware error).

DevTools

When DevTools are enabled alongside metrics, the panel's Metrics tab renders these numbers live — usually all you need during development.