Refactoring the access to the Jenkins services through a caching DAO layer

MiniCache is not thread-safe (derp) so smashing a Concurrent::Hash into it
should solve that problem

RUBY AMIRITE

.gitignore

@@ -50,3 +50,4 @@ build-iPhoneSimulator/
 # unless supporting rvm < 1.11.0 or doing something fancy, ignore this:
 .rvmrc
 vendor/
+*.html

Gemfile

@@ -1,7 +1,10 @@
 source 'https://rubygems.org'
 
+gem 'concurrent-ruby'
+gem 'faraday'
+gem 'faraday_middleware'
 gem 'haml'
-gem 'httparty'
+gem 'mini_cache'
 gem 'puma'
 gem 'sentry-raven'
 gem 'sentry-api'

Gemfile.lock

@@ -1,9 +1,12 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    concurrent-ruby (1.0.5)
     diff-lcs (1.3)
     faraday (0.13.1)
       multipart-post (>= 1.2, < 3)
+    faraday_middleware (0.12.2)
+      faraday (>= 0.7.4, < 1.0)
     haml (5.0.2)
       temple (>= 0.8.0)
       tilt
@@ -14,6 +17,7 @@ GEM
     httparty (0.15.6)
       multi_xml (>= 0.5.2)
     mimemagic (0.3.2)
+    mini_cache (1.1.0)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
     mustermann (1.0.1)
@@ -50,8 +54,11 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  concurrent-ruby
+  faraday
+  faraday_middleware
   haml
-  httparty
+  mini_cache
   puma
   rspec
   sentry-api

Jenkinsfile

@@ -12,6 +12,9 @@ pipeline {
             steps {
                 sh 'make check'
             }
+            always {
+                archiveArtifacts 'rspec.html'
+            }
         }
         stage('Build container') {
             steps {

Makefile

@@ -4,7 +4,10 @@ all: check container
 check: spec check-container
 
 spec: depends
-	./scripts/ruby bundle exec rspec -c
+	./scripts/ruby bundle exec rspec -c \
+						--order random \
+						--format progress \
+						--format html --out rspec.html
 
 depends: Gemfile
 	./scripts/ruby bundle install

app/canary.rb

@@ -5,7 +5,7 @@ require 'raven'
 require 'sinatra/base'
 require 'sentry-api'
 
-require 'canary/jenkins'
+require 'canary/dao/jenkins'
 
 module CodeValet
   module Canary
@@ -35,7 +35,7 @@ module CodeValet
               :layout => :_base,
               :locals => {
                   :projects => projects,
-                  :jenkins => Jenkins,
+                  :jenkins => DAO::Jenkins.new,
               }
       end
 

app/canary/dao.rb

@@ -0,0 +1,30 @@
+require 'concurrent/hash'
+require 'mini_cache'
+
+module CodeValet
+  module Canary
+    # The DAO module contains some data-access objects which are to be used
+    # from the web tier.
+    module DAO
+      # Unless otherwise specified, cached entries should "live" for this
+      # number of seconds
+      DEFAULT_CACHE_SECONDS = 120
+
+      # Access the caching object
+      #
+      # @returs [MiniCache::Store]
+      def self.cache
+        return @cache unless @cache.nil?
+
+        @cache = MiniCache::Store.new
+        @cache.instance_variable_set(:@data, Concurrent::Hash.new)
+        return @cache
+      end
+
+      # Reset the cache, primarily intended for testing
+      def self.clear_cache
+        @cache = nil
+      end
+    end
+  end
+end

app/canary/dao/jenkins.rb

@@ -0,0 +1,50 @@
+require 'faraday'
+require 'canary/dao'
+
+module CodeValet::Canary::DAO
+  class Jenkins
+    # Base URL to contrict 
+    URL_BASE = ENV['JENKINS_URL_BASE'] || 'https://codevalet.io'
+    CACHE_SECONDS = 300
+
+    attr_reader :error
+
+    def errored?
+      return !@error.nil?
+    end
+
+    def rebuiltAlpha
+      return cache.get_or_set('rebuiltAlpha', :expires_in => CACHE_SECONDS) do
+        rebuiltFor('codevalet')
+      end
+    end
+
+    def rebuiltGA
+      return cache.get_or_set('rebuiltGA', :expires_in => CACHE_SECONDS) do
+        rebuiltFor('rtyler')
+      end
+    end
+
+    # Method for directly querying a Jenkins instance to ask when it was last
+    # rebuilt
+    #
+    # @return [String] response from the server if we reached it
+    # @return [nil] nil on no response, #errored? should be set
+    def rebuiltFor(user)
+      # NOTE: worth investigating whether Jenkins will provide the appropriate
+      # caching headers to 
+      url = "#{URL_BASE}/u/#{user}/userContent/builtOn.txt"
+      response = Faraday.get(url)
+      if response.success?
+        return response.body
+      end
+      @error = response.status
+      return nil
+    end
+
+    private
+    def cache
+      return CodeValet::Canary::DAO.cache
+    end
+  end
+end

app/canary/jenkins.rb

@@ -1,27 +0,0 @@
-require 'httparty'
-
-module CodeValet
-  module Canary
-    class Jenkins
-      URL_BASE = ENV['JENKINS_URL_BASE'] || 'https://codevalet.io'
-
-      # https://codevalet.io/u/codevalet/userContent/builtOn.txt
-      def self.rebuiltAlpha
-        return self.rebuiltUrlFor('codevalet')
-      end
-
-      def self.rebuiltGa
-        return self.rebuiltUrlFor('rtyler')
-      end
-
-      def self.rebuiltUrlFor(user)
-        url = "#{URL_BASE}/u/#{user}/userContent/builtOn.txt"
-        response = HTTParty.get(url)
-        if response.ok?
-          return response.body
-        end
-        return 'failed to retrieve last built information..'
-      end
-    end
-  end
-end

spec/dao/jenkins_spec.rb

@@ -0,0 +1,43 @@
+require 'spec_helper'
+
+require 'canary/dao/jenkins'
+
+describe CodeValet::Canary::DAO::Jenkins do
+  before :each do
+    CodeValet::Canary::DAO.clear_cache
+  end
+
+  context 'a bare instance' do
+    it { should_not be_errored }
+
+    context 'with a stubbed network call' do
+      let(:response) { 'stubbed!' }
+      before :each do
+        expect(subject).to receive(:rebuiltFor).and_return(response)
+      end
+
+      it 'provides a response on #rebuiltAlpha' do
+        expect(subject.rebuiltAlpha).to eql(response)
+      end
+
+      it 'provides a response on #rebuiltGA' do
+        expect(subject.rebuiltGA).to eql(response)
+      end
+
+      it 'should cache subsequent calls on #rebuiltAlpha' do
+        3.times do
+          expect(subject.rebuiltAlpha).to eql(response)
+        end
+      end
+
+      it 'should cache subsequent calls on #rebuiltGA' do
+        3.times do
+          expect(subject.rebuiltGA).to eql(response)
+        end
+      end
+    end
+  end
+
+  context 'with network errors' do
+  end
+end

spec/dao_spec.rb

@@ -0,0 +1,8 @@
+require 'spec_helper'
+
+require 'canary/dao'
+
+describe CodeValet::Canary::DAO do
+  it { should respond_to :cache }
+  it { should respond_to :clear_cache }
+end

spec/spec_helper.rb

@@ -0,0 +1,3 @@
+require 'rspec'
+
+$LOAD_PATH.unshift << File.expand_path(File.dirname(__FILE__) + '/../app')

views/index.haml

@@ -31,7 +31,7 @@
             general availability
           channel was last rebuilt on:
           %code
-            = jenkins.rebuiltGa
+            = jenkins.rebuiltGA
 
   .row
     .col-md-12