# Simple mixin
module Loggable
  def log(message)
    puts "[#{Time.now}] #{self.class.name}: #{message}"
  end
end

# BAD: N+1 query problem
@users = User.all
@users.each do |user|
  puts user.posts.count  # Fires query for each user!
end

class Timer
  def self.measure
    start_time = Time.now
    yield if block_given?
    end_time = Time.now
    end_time - start_time

class UserNotificationJob < ApplicationJob
  queue_as :default

  # Retry up to 5 times with exponential backoff
  retry_on StandardError, wait: :exponentially_longer, attempts: 5

require 'rails_helper'

RSpec.describe User, type: :model do
  subject(:user) { build(:user) }

  describe 'validations' do

class UserRegistrationService
  class Result
    attr_reader :user, :errors

    def initialize(success:, user: nil, errors: [])
      @success = success

class DynamicFinder
  def initialize(records)
    @records = records
  end

  def method_missing(method_name, *args, &block)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: user-service
  labels:
    app: user-service

package com.example.demo.service;

import io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker;
import io.github.resilience4j.ratelimiter.annotation.RateLimiter;
import io.github.resilience4j.retry.annotation.Retry;
import io.github.resilience4j.bulkhead.annotation.Bulkhead;

package com.example.demo.aspect;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.slf4j.Logger;

package com.example.demo.multitenancy;

public class TenantContext {
    private static final ThreadLocal<String> CURRENT_TENANT = new ThreadLocal<>();

    public static void setTenantId(String tenantId) {

package com.example.demo.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.context.annotation.Bean;