V0.1.1

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  rubocop:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+      - run: bundle exec rubocop
+
+  rspec:
+    runs-on: ubuntu-latest
+    services:
+      redis:
+        image: redis:7
+        ports:
+          - 6379:6379
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+      - run: bundle exec rspec --tag ~system
+        env:
+          RACK_ENV: test

.rspec

@@ -0,0 +1 @@
+--require spec_helper

.rubocop.yml

@@ -1,11 +1,21 @@
 AllCops:
   NewCops: enable
+  Exclude:
+    - '.gems/**/*'
+    - '.direnv/**/*'
+    - 'vendor/**/*'
+    - '.bundle/**/*'
+
 
 Style/Documentation:
   Enabled: false
 
 Metrics/MethodLength:
   Enabled: false
 
+Metrics/BlockLength:
+  Exclude:
+    - 'spec/**/*'
+
 Lint/UnusedMethodArgument:
   Enabled: false

Gemfile

@@ -7,11 +7,15 @@ ruby '4.0.3'
 gem 'activerecord'
 gem 'pg'
 gem 'puma'
+gem 'rake'
 gem 'redis'
 gem 'sinatra'
+gem 'sinatra-activerecord'
 
-group :development do
-  gem 'rubocop'
+group :development, :test do
+  gem 'rack-test'
+  gem 'rspec'
   gem 'ruby-lsp'
   gem 'solargraph'
+  gem 'standard', '>= 1.35.1'
 end

Gemfile.lock

@@ -50,7 +50,7 @@ GEM
     observer (0.1.2)
     open3 (0.2.1)
     ostruct (0.6.3)
-    parallel (2.1.0)
+    parallel (1.28.0)
     parser (3.3.11.1)
       ast (~> 2.4.1)
       racc
@@ -68,7 +68,10 @@ GEM
     rack-session (2.1.2)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
+    rack-test (2.2.0)
+      rack (>= 1.3)
     rainbow (3.1.1)
+    rake (13.4.2)
     rbs (4.0.2)
       logger
       prism (>= 1.6.0)
@@ -81,11 +84,24 @@ GEM
     reverse_markdown (3.0.2)
       nokogiri
     rexml (3.4.4)
-    rubocop (1.86.2)
+    rspec (3.13.2)
+      rspec-core (~> 3.13.0)
+      rspec-expectations (~> 3.13.0)
+      rspec-mocks (~> 3.13.0)
+    rspec-core (3.13.6)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-mocks (3.13.8)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-support (3.13.7)
+    rubocop (1.84.2)
       json (~> 2.3)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.1.0)
-      parallel (>= 1.10)
+      parallel (~> 1.10)
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 2.9.3, < 3.0)
@@ -95,6 +111,10 @@ GEM
     rubocop-ast (1.49.1)
       parser (>= 3.3.7.2)
       prism (~> 1.7)
+    rubocop-performance (1.26.1)
+      lint_roller (~> 1.1)
+      rubocop (>= 1.75.0, < 2.0)
+      rubocop-ast (>= 1.47.1, < 2.0)
     ruby-lsp (0.26.9)
       language_server-protocol (~> 3.17.0)
       prism (>= 1.2, < 2.0)
@@ -108,6 +128,9 @@ GEM
       rack-protection (= 4.2.1)
       rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
+    sinatra-activerecord (2.0.28)
+      activerecord (>= 4.1)
+      sinatra (>= 1.0)
     solargraph (0.59.0)
       ast (~> 2.4.3)
       backport (~> 1.2)
@@ -131,6 +154,18 @@ GEM
       yard (~> 0.9, >= 0.9.24)
       yard-activesupport-concern (~> 0.0)
       yard-solargraph (~> 0.1)
+    standard (1.54.0)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.84.0)
+      standard-custom (~> 1.0.0)
+      standard-performance (~> 1.8)
+    standard-custom (1.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.50)
+    standard-performance (1.9.0)
+      lint_roller (~> 1.1)
+      rubocop-performance (~> 1.26.0)
     thor (1.5.0)
     tilt (2.7.0)
     timeout (0.6.1)
@@ -154,11 +189,15 @@ DEPENDENCIES
   activerecord
   pg
   puma
+  rack-test
+  rake
   redis
-  rubocop
+  rspec
   ruby-lsp
   sinatra
+  sinatra-activerecord
   solargraph
+  standard (>= 1.35.1)
 
 CHECKSUMS
   activemodel (8.1.3) sha256=90c05cbe4cef3649b8f79f13016191ea94c4525ce4a5c0fb7ef909c4b91c8219
@@ -188,7 +227,7 @@ CHECKSUMS
   observer (0.1.2) sha256=d8a3107131ba661138d748e7be3dbafc0d82e732fffba9fccb3d7829880950ac
   open3 (0.2.1) sha256=8e2d7d2113526351201438c1aa35c8139f0141c9e8913baa007c898973bf3952
   ostruct (0.6.3) sha256=95a2ed4a4bd1d190784e666b47b2d3f078e4a9efda2fccf18f84ddc6538ed912
-  parallel (2.1.0) sha256=b35258865c2e31134c5ecb708beaaf6772adf9d5efae28e93e99260877b09356
+  parallel (1.28.0) sha256=33e6de1484baf2524792d178b0913fc8eb94c628d6cfe45599ad4458c638c970
   parser (3.3.11.1) sha256=d17ace7aabe3e72c3cc94043714be27cc6f852f104d81aa284c2281aecc65d54
   pg (1.6.3) sha256=1388d0563e13d2758c1089e35e973a3249e955c659592d10e5b77c468f628a99
   pg (1.6.3-x86_64-linux) sha256=5d9e188c8f7a0295d162b7b88a768d8452a899977d44f3274d1946d67920ae8d
@@ -198,20 +237,32 @@ CHECKSUMS
   rack (3.2.6) sha256=5ed78e1f73b2e25679bec7d45ee2d4483cc4146eb1be0264fc4d94cb5ef212c2
   rack-protection (4.2.1) sha256=cf6e2842df8c55f5e4d1a4be015e603e19e9bc3a7178bae58949ccbb58558bac
   rack-session (2.1.2) sha256=595434f8c0c3473ae7d7ac56ecda6cc6dfd9d37c0b2b5255330aa1576967ffe8
+  rack-test (2.2.0) sha256=005a36692c306ac0b4a9350355ee080fd09ddef1148a5f8b2ac636c720f5c463
   rainbow (3.1.1) sha256=039491aa3a89f42efa1d6dec2fc4e62ede96eb6acd95e52f1ad581182b79bc6a
+  rake (13.4.2) sha256=cb825b2bd5f1f8e91ca37bddb4b9aaf345551b4731da62949be002fa89283701
   rbs (4.0.2) sha256=af75671e66cd03434cc546622741ebf83f6197ec4328375805306330bf78ef25
   redis (5.4.1) sha256=b5e675b57ad22b15c9bcc765d5ac26f60b675408af916d31527af9bd5a81faae
   redis-client (0.29.0) sha256=0c65bf1f8f6dca22063ddb085c0bb2054feef6f03a84869f4161b18a9a15bea3
   regexp_parser (2.12.0) sha256=35a916a1d63190ab5c9009457136ae5f3c0c7512d60291d0d1378ba18ce08ebb
   reverse_markdown (3.0.2) sha256=818ebb92ce39dbb1a291690dd1ec9a6d62530d4725296b17e9c8f668f9a5b8af
   rexml (3.4.4) sha256=19e0a2c3425dfbf2d4fc1189747bdb2f849b6c5e74180401b15734bc97b5d142
-  rubocop (1.86.2) sha256=bb2e97f635eda42c448f2588f4a6ff78f221b8bdfdf65b1e9b07fbd57521b45d
+  rspec (3.13.2) sha256=206284a08ad798e61f86d7ca3e376718d52c0bc944626b2349266f239f820587
+  rspec-core (3.13.6) sha256=a8823c6411667b60a8bca135364351dda34cd55e44ff94c4be4633b37d828b2d
+  rspec-expectations (3.13.5) sha256=33a4d3a1d95060aea4c94e9f237030a8f9eae5615e9bd85718fe3a09e4b58836
+  rspec-mocks (3.13.8) sha256=086ad3d3d17533f4237643de0b5c42f04b66348c28bf6b9c2d3f4a3b01af1d47
+  rspec-support (3.13.7) sha256=0640e5570872aafefd79867901deeeeb40b0c9875a36b983d85f54fb7381c47c
+  rubocop (1.84.2) sha256=5692cea54168f3dc8cb79a6fe95c5424b7ea893c707ad7a4307b0585e88dbf5f
   rubocop-ast (1.49.1) sha256=4412f3ee70f6fe4546cc489548e0f6fcf76cafcfa80fa03af67098ffed755035
+  rubocop-performance (1.26.1) sha256=cd19b936ff196df85829d264b522fd4f98b6c89ad271fa52744a8c11b8f71834
   ruby-lsp (0.26.9) sha256=33a01c001c00a76b4e821efc04ed7572983430f31ca5d6f3e343d0b6ccab4129
   ruby-progressbar (1.13.0) sha256=80fc9c47a9b640d6834e0dc7b3c94c9df37f08cb072b7761e4a71e22cff29b33
   securerandom (0.4.1) sha256=cc5193d414a4341b6e225f0cb4446aceca8e50d5e1888743fac16987638ea0b1
   sinatra (4.2.1) sha256=b7aeb9b11d046b552972ade834f1f9be98b185fa8444480688e3627625377080
+  sinatra-activerecord (2.0.28) sha256=99f352c2dfa244d02b4f877efbe00135360b758390b8bb7bc2d4d91171c93811
   solargraph (0.59.0) sha256=229845d4ce99b6259e3d7fd9c8238f9cd74c3056e59a4a16fb1525d6a790dad3
+  standard (1.54.0) sha256=7a4b08f83d9893083c8f03bc486f0feeb6a84d48233b40829c03ef4767ea0100
+  standard-custom (1.0.2) sha256=424adc84179a074f1a2a309bb9cf7cd6bfdb2b6541f20c6bf9436c0ba22a652b
+  standard-performance (1.9.0) sha256=49483d31be448292951d80e5e67cdcb576c2502103c7b40aec6f1b6e9c88e3f2
   thor (1.5.0) sha256=e3a9e55fe857e44859ce104a84675ab6e8cd59c650a49106a05f55f136425e73
   tilt (2.7.0) sha256=0d5b9ba69f6a36490c64b0eee9f6e9aad517e20dcc848800a06eb116f08c6ab3
   timeout (0.6.1) sha256=78f57368a7e7bbadec56971f78a3f5ecbcfb59b7fcbb0a3ed6ddc08a5094accb

README.md

@@ -11,6 +11,7 @@ Ruby developers who want to go beyond CRUD and learn how to handle high traffic,
 | Problem | Description | Difficulty |
 |---------|-------------|------------|
 | [Cache Stampede](lib/ruby_at_scale/cache_stampede/) | Prevent 1000 concurrent requests from hammering your DB when cache expires | Medium |
+| [Rate Limiter](lib/ruby_at_scale/rate_limiter/) | Atomic sliding window rate limiting under high concurrency | Medium |
 
 ## How it works
 
@@ -23,7 +24,13 @@ Ruby developers who want to go beyond CRUD and learn how to handle high traffic,
 
 ```bash
 bundle install
-bin/setup
+```
+
+Update `config/database.yml` with your PostgreSQL credentials, then:
+
+```bash
+rake db:create
+rake db:migrate
 ```
 
 ## Run
@@ -35,8 +42,12 @@ bin/server
 ## Test
 
 ```bash
-# Cache Stampede
-test/ruby_at_scale/cache_stampede_test
+# Unit/Integration specs
+rspec --tag ~system
+
+# System tests (interactive, requires running PostgreSQL and Redis)
+spec/system/bin/cache_stampede_test
+spec/system/bin/rate_limiter_test
 ```
 
 ## Dependencies

Rakefile

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+ENV['RACK_ENV'] ||= 'production'
+
+require_relative 'lib/ruby_at_scale'
+require 'sinatra/activerecord/rake'

config.ru

@@ -2,15 +2,5 @@
 
 require_relative 'lib/ruby_at_scale'
 
-get '/report' do
-  content_type :json
-
-  result = RubyAtScale::CacheStampede.cache.fetch('expensive_report', ttl: 60) do
-    RubyAtScale::CacheStampede.redis.incr('stampede:query_count')
-    RubyAtScale::CacheStampede.expensive_query
-  end
-
-  { pid: Process.pid, result_size: result.to_s.length }.to_json
-end
-
-run Sinatra::Application
+map('/report')  { run RubyAtScale::Controllers::ReportsController }
+map('/limited') { run RubyAtScale::Controllers::RateLimitController }

config/database.yml

@@ -1,6 +1,13 @@
-development:
+test:
   adapter: postgresql
   host: localhost
-  database: ruby_at_scale
-  username: <%= ENV.fetch('PGUSER', 'postgres') %>
-  password: <%= ENV.fetch('PGPASSWORD', '') %>
+  database: ruby_at_scale_test
+  username: postgres
+  password:
+
+production:
+  adapter: postgresql
+  host: localhost
+  database: ruby_at_scale_production
+  username: postgres
+  password:

config/puma.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+environment ENV.fetch('RACK_ENV', 'production')
+
 workers 4
 threads_count = 5
 threads threads_count, threads_count

config/routes.rb

@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+map('/report')  { run RubyAtScale::Controllers::ReportsController }
+map('/limited') { run RubyAtScale::Controllers::RateLimitController }

db/migrate/20260520000001_create_events.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class CreateEvents < ActiveRecord::Migration[7.1]
+  def change
+    create_table :events do |t|
+      t.string :event_type
+      t.decimal :amount, precision: 10, scale: 2
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+# This file is auto-generated from the current state of the database. Instead
+# of editing this file, please use the migrations feature of Active Record to
+# incrementally modify your database, and then regenerate this schema definition.
+#
+# This file is the source Rails uses to define your schema when running `bin/rails
+# db:schema:load`. When creating a new database, `bin/rails db:schema:load` tends to
+# be faster and is potentially less error prone than running all of your
+# migrations from scratch. Old migrations may fail to apply correctly if those
+# migrations use external dependencies or application code.
+#
+# It's strongly recommended that you check this file into your version control system.
+
+ActiveRecord::Schema[8.1].define(version: 20_260_520_000_001) do
+  # These are extensions that must be enabled in order to support this database
+  enable_extension 'pg_catalog.plpgsql'
+
+  create_table 'events', force: :cascade do |t|
+    t.decimal 'amount', precision: 10, scale: 2
+    t.datetime 'created_at', null: false
+    t.string 'event_type'
+    t.datetime 'updated_at', null: false
+  end
+end