add-custom-metrics-to-your-application

description: Use Effect's Metric module to define and update custom metrics for business and performance monitoring. globs: "**/*.ts" alwaysApply: true

Add Custom Metrics to Your Application

Rule: Use Effect's Metric module to define and update custom metrics for business and performance monitoring.

Example

import { Effect, Metric } from "effect";

// Define a counter metric for processed jobs
const jobsProcessed = Metric.counter("jobs_processed");

// Increment the counter when a job is processed
const processJob = Effect.gen(function* () {
  // ... process the job
  yield* Effect.log("Job processed");
  yield* Metric.increment(jobsProcessed);
});

// Define a gauge for current active users
const activeUsers = Metric.gauge("active_users");

// Update the gauge when users sign in or out
const userSignedIn = Metric.set(activeUsers, 1); // Set to 1 (simplified example)
const userSignedOut = Metric.set(activeUsers, 0); // Set to 0 (simplified example)

// Define a histogram for request durations
const requestDuration = Metric.histogram("request_duration", [
  0.1, 0.5, 1, 2, 5,
] as any); // boundaries in seconds

// Record a request duration
const recordDuration = (duration: number) =>
  Metric.update(requestDuration, duration);

Explanation:

• Metric.counter tracks counts of events.
• Metric.gauge tracks a value that can go up or down (e.g., active users).
• Metric.histogram tracks distributions (e.g., request durations).
• Effect.updateMetric updates the metric in your workflow.

Explanation:
Metrics provide quantitative insight into your application's behavior and performance.
By instrumenting your code with metrics, you can monitor key events, detect anomalies, and drive business decisions.