metrics

import { onCLS, onINP, onLCP, onFCP, onTTFB, type Metric } from 'web-vitals';

export interface VitalPayload {
  id: string;
  name: Metric['name'];
  value: number;

import { Registry, Histogram, Counter, collectDefaultMetrics } from 'prom-client';

export const register = new Registry();

collectDefaultMetrics({ register });

class CheckoutService
  def initialize(cart:, user:)
    @cart = cart
    @user = user
  end

-- Enable pg_stat_statements extension
CREATE EXTENSION IF NOT EXISTS pg_stat_statements;

-- postgresql.conf:
-- shared_preload_libraries = 'pg_stat_statements'
-- pg_stat_statements.track = all

package observability

import (
  "expvar"
  "net/http"
)

class ExternalApiClient
  def fetch_user_data(user_id)
    ActiveSupport::Notifications.instrument(
      'api.external_service',
      service: 'user_service',
      operation: 'fetch_user',

package com.example.demo.service;

import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Timer;
import org.springframework.stereotype.Service;

package metrics

import (
  "net/http"
  "strconv"
  "time"

use std::collections::HashMap;
use std::sync::{Arc, Mutex, PoisonError};

#[derive(Default)]
struct Metrics {
    per_endpoint: HashMap<String, u64>,

-- Connection statistics
SELECT
  count(*) AS total_connections,
  count(*) FILTER (WHERE state = 'active') AS active,
  count(*) FILTER (WHERE state = 'idle') AS idle,
  count(*) FILTER (WHERE state = 'idle in transaction') AS idle_in_tx,

class DeliveryObserver
  def self.delivered_email(message)
    new(message).record
  end

  def initialize(message)

package main

import (
	"log"
	"net/http"
	"time"