Add repository languages for projects

Our friends at GitHub show the programming languages for a long time,
and inspired by that this commit means to create about the same
functionality.

Language detection is done through Linguist, as before, where the
difference is that we cache the result in the database. Also, Gitaly can
incrementaly scan a repository. This is done through a shell out, which
creates overhead of about 3s each run. For now this won't be improved.

Scans are triggered by pushed to the default branch, usually `master`.
However, one exception to this rule the charts page. If we're requesting
this expensive data anyway, we just cache it in the database.

Edge cases where there is no repository, or its empty are caught in the
Repository model. This makes use of Redis caching, which is probably
already loaded.

The added model is called RepositoryLanguage, which will make it harder
if/when GitLab supports multiple repositories per project. However, for
now I think this shouldn't be a concern. Also, Language could be
confused with the i18n languages and felt like the current name was
suiteable too.

Design of the Project#Show page is done with help from @dimitrieh. This
change is not visible to the end user unless detections are done.

app/assets/stylesheets/pages/projects.scss

@@ -754,6 +754,11 @@
   }
 }
 
+.repository-languages-bar {
+  height: 6px;
+  margin-bottom: 8px;
+}
+
 pre.light-well {
   border-color: $well-light-border;
 }

app/helpers/repository_languages_helper.rb

@@ -0,0 +1,16 @@
+module RepositoryLanguagesHelper
+  def repository_languages_bar(languages)
+    return if languages.none?
+
+    content_tag :div, class: 'progress repository-languages-bar' do
+      safe_join(languages.map { |lang| language_progress(lang) })
+    end
+  end
+
+  def language_progress(lang)
+    content_tag :div, nil,
+      class: "progress-bar has-tooltip",
+      style: "width: #{lang.share}%; background-color:#{lang.color}",
+      title: lang.name
+  end
+end

app/models/namespace.rb

@@ -122,6 +122,7 @@ class Namespace < ActiveRecord::Base
   def to_param
     full_path
   end
+  alias_method :flipper_id, :to_param
 
   def human_name
     owner_name

app/models/programming_language.rb

@@ -0,0 +1,4 @@
+class ProgrammingLanguage < ActiveRecord::Base
+  validates :name, presence: true
+  validates :color, allow_blank: false, color: true
+end

app/models/project.rb

@@ -192,6 +192,7 @@ class Project < ActiveRecord::Base
   has_many :hooks, class_name: 'ProjectHook'
   has_many :protected_branches
   has_many :protected_tags
+  has_many :repository_languages, -> { order "share DESC" }
 
   has_many :project_authorizations
   has_many :authorized_users, through: :project_authorizations, source: :user, class_name: 'User'

app/models/repository.rb

@@ -235,6 +235,12 @@ class Repository
     false
   end
 
+  def languages
+    return [] if empty?
+
+    raw_repository.languages(root_ref)
+  end
+
   # Makes sure a commit is kept around when Git garbage collection runs.
   # Git GC will delete commits from the repository that are no longer in any
   # branches or tags, but we want to keep some of these commits around, for
@@ -432,6 +438,8 @@ class Repository
   # Runs code after a repository has been forked/imported.
   def after_import
     expire_content_cache
+
+    DetectRepositoryLanguagesWorker.perform_async(project.id, project.owner.id)
   end
 
   # Runs code after a new commit has been pushed.

app/models/repository_language.rb

@@ -0,0 +1,12 @@
+class RepositoryLanguage < ActiveRecord::Base
+  belongs_to :project
+  belongs_to :programming_language
+
+  default_scope { includes(:programming_language) }
+
+  validates :project, presence: true
+  validates :share, inclusion: { in: 0..100, message: "The share of a lanuage is between 0 and 100" }
+  validates :programming_language, uniqueness: { scope: :project_id }
+
+  delegate :name, :color, to: :programming_language
+end

app/services/git_push_service.rb

@@ -85,6 +85,8 @@ class GitPushService < BaseService
 
         types = Gitlab::FileDetector.types_in_paths(paths.to_a)
       end
+
+      DetectRepositoryLanguagesWorker.perform_async(@project.id, current_user.id)
     else
       types = []
     end

app/services/projects/detect_repository_languages_service.rb

@@ -0,0 +1,53 @@
+module Projects
+  class DetectRepositoryLanguagesService < BaseService
+    attr_reader :detected_repository_languages, :programming_languages
+
+    def execute
+      repository_languages = project.repository_languages
+      detection = Gitlab::LanguageDetection.new(repository, repository_languages)
+
+      matching_programming_languages = ensure_programming_languages(detection)
+
+      RepositoryLanguage.transaction do
+        project.repository_languages.where(programming_language_id: detection.deletions).delete_all
+
+        detection.updates.each do |update|
+          RepositoryLanguage
+            .arel_table.update_manager
+            .where(project_id: project.id)
+            .where(programming_language_id: update[:programming_language_id])
+            .set(share: update[:share])
+        end
+
+        Gitlab::Database.bulk_insert(
+          RepositoryLanguage.table_name,
+          detection.insertions(matching_programming_languages)
+        )
+      end
+
+      project.repository_languages.reload
+    end
+
+    private
+
+    def ensure_programming_languages(detection)
+      existing_languages = ProgrammingLanguage.where(name: detection.languages)
+      return existing_languages if detection.languages.size == existing_languages.size
+
+      missing_languages = detection.languages - existing_languages.map(&:name)
+      created_languages = missing_languages.map do |name|
+        create_language(name, detection.language_color(name))
+      end
+
+      existing_languages + created_languages
+    end
+
+    def create_language(name, color)
+      ProgrammingLanguage.transaction do
+        ProgrammingLanguage.where(name: name).first_or_create(color: color)
+      end
+    rescue ActiveRecord::RecordNotUnique
+      retry
+    end
+  end
+end

app/views/projects/show.html.haml

@@ -18,10 +18,11 @@
 = render "home_panel"
 
 - if can?(current_user, :download_code, @project)
-  %nav.project-stats{ class: container_class }
+  %nav.project-stats{ class: [container_class, ("limit-container-width" unless fluid_layout)] }
     = render 'stat_anchor_list', anchors: @project.statistics_anchors(show_auto_devops_callout: show_auto_devops_callout)
     = render 'stat_anchor_list', anchors: @project.statistics_buttons(show_auto_devops_callout: show_auto_devops_callout)
-
+    - if Feature.enabled?(:repository_languages, @project.namespace.becomes(Namespace))
+      = repository_languages_bar(@project.repository_languages)
 
 %div{ class: [container_class, ("limit-container-width" unless fluid_layout)] }
   - if @project.archived?

app/workers/all_queues.yml

@@ -123,3 +123,4 @@
 - repository_update_remote_mirror
 - create_note_diff_file
 - delete_diff_files
+- detect_repository_languages

app/workers/detect_repository_languages_worker.rb

@@ -0,0 +1,33 @@
+class DetectRepositoryLanguagesWorker
+  include ApplicationWorker
+  include ExceptionBacktrace
+  include ExclusiveLeaseGuard
+
+  sidekiq_options retry: 1
+
+  LEASE_TIMEOUT = 300
+
+  attr_reader :project
+
+  def perform(project_id, user_id)
+    @project = Project.find_by(id: project_id)
+    user = User.find_by(id: user_id)
+    return unless project && user
+
+    return if Feature.disabled?(:repository_languages, project.namespace)
+
+    try_obtain_lease do
+      ::Projects::DetectRepositoryLanguagesService.new(project, user).execute
+    end
+  end
+
+  private
+
+  def lease_timeout
+    LEASE_TIMEOUT
+  end
+
+  def lease_key
+    "gitlab:detect_repository_languages:#{project.id}"
+  end
+end

changelogs/unreleased/zj-repository-languages.yml

@@ -0,0 +1,5 @@
+---
+title: Show repository languages for projects
+merge_request: 19480
+author:
+type: added

config/sidekiq_queues.yml

@@ -77,3 +77,4 @@
   - [repository_remove_remote, 1]
   - [create_note_diff_file, 1]
   - [delete_diff_files, 1]
+  - [detect_repository_languages, 1]

db/migrate/20180531185349_add_repository_languages.rb

@@ -0,0 +1,28 @@
+class AddRepositoryLanguages < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    create_table(:programming_languages) do |t|
+      t.string :name, null: false
+      t.string :color, null: false
+      t.datetime_with_timezone :created_at, null: false
+    end
+
+    create_table(:repository_languages, id: false) do |t|
+      t.references :project, null: false, foreign_key: { on_delete: :cascade }
+      t.references :programming_language, null: false
+      t.float :share, null: false
+    end
+
+    add_index :programming_languages, :name, unique: true
+    add_index :repository_languages, [:project_id, :programming_language_id],
+      unique: true, name: "index_repository_languages_on_project_and_languages_id"
+  end
+
+  def down
+    drop_table :repository_languages
+    drop_table :programming_languages
+  end
+end

db/schema.rb

@@ -1502,6 +1502,14 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_index "personal_access_tokens", ["token"], name: "index_personal_access_tokens_on_token", unique: true, using: :btree
   add_index "personal_access_tokens", ["user_id"], name: "index_personal_access_tokens_on_user_id", using: :btree
 
+  create_table "programming_languages", force: :cascade do |t|
+    t.string "name", null: false
+    t.string "color", null: false
+    t.datetime_with_timezone "created_at", null: false
+  end
+
+  add_index "programming_languages", ["name"], name: "index_programming_languages_on_name", unique: true, using: :btree
+
   create_table "project_authorizations", id: false, force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "project_id", null: false
@@ -1788,6 +1796,14 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_index "remote_mirrors", ["last_successful_update_at"], name: "index_remote_mirrors_on_last_successful_update_at", using: :btree
   add_index "remote_mirrors", ["project_id"], name: "index_remote_mirrors_on_project_id", using: :btree
 
+  create_table "repository_languages", id: false, force: :cascade do |t|
+    t.integer "project_id", null: false
+    t.integer "programming_language_id", null: false
+    t.float "share", null: false
+  end
+
+  add_index "repository_languages", ["project_id", "programming_language_id"], name: "index_repository_languages_on_project_and_languages_id", unique: true, using: :btree
+
   create_table "resource_label_events", id: :bigserial, force: :cascade do |t|
     t.integer "action", null: false
     t.integer "issue_id"
@@ -2359,6 +2375,7 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_foreign_key "push_event_payloads", "events", name: "fk_36c74129da", on_delete: :cascade
   add_foreign_key "releases", "projects", name: "fk_47fe2a0596", on_delete: :cascade
   add_foreign_key "remote_mirrors", "projects", on_delete: :cascade
+  add_foreign_key "repository_languages", "projects", on_delete: :cascade
   add_foreign_key "resource_label_events", "issues", on_delete: :cascade
   add_foreign_key "resource_label_events", "labels", on_delete: :nullify
   add_foreign_key "resource_label_events", "merge_requests", on_delete: :cascade

lib/feature.rb

@@ -46,6 +46,10 @@ class Feature
       get(key).enabled?(thing)
     end
 
+    def disabled?(key, thing = nil)
+      !enabled?(key, thing)
+    end
+
     def enable(key, thing = true)
       get(key).enable(thing)
     end

lib/gitlab/import_export/import_export.yml

@@ -107,6 +107,7 @@ excluded_attributes:
     - :storage_version
     - :remote_mirror_available_overridden
     - :description_html
+    - :repository_languages
   snippets:
     - :expired_at
   merge_request_diff:

lib/gitlab/language_detection.rb

@@ -0,0 +1,68 @@
+module Gitlab
+  class LanguageDetection
+    MAX_LANGUAGES = 5
+
+    def initialize(repository, repository_languages)
+      @repository = repository
+      @repository_languages = repository_languages
+    end
+
+    def languages
+      detection.keys
+    end
+
+    def language_color(name)
+      detection.dig(name, :color)
+    end
+
+    # Newly detected languages, returned in a structure accepted by
+    # Gitlab::Database.bulk_insert
+    def insertions(programming_languages)
+      lang_to_id = programming_languages.map { |p| [p.name, p.id] }.to_h
+
+      (languages - previous_language_names).map do |new_lang|
+        {
+          project_id: @repository.project.id,
+          share: detection[new_lang][:value],
+          programming_language_id: lang_to_id[new_lang]
+        }
+      end
+    end
+
+    # updates analyses which records only require updating of their share
+    def updates
+      to_update = @repository_languages.select do |lang|
+        detection.key?(lang.name) && detection[lang.name][:value] != lang.share
+      end
+
+      to_update.map do |lang|
+        { programming_language_id: lang.programming_language_id, share: detection[lang.name][:value] }
+      end
+    end
+
+    # Returns the ids of the programming languages that do not occur in the detection
+    # as current repository languages
+    def deletions
+      @repository_languages.map do |repo_lang|
+        next if detection.key?(repo_lang.name)
+
+        repo_lang.programming_language_id
+      end.compact
+    end
+
+    private
+
+    def previous_language_names
+      @previous_language_names ||= @repository_languages.map(&:name)
+    end
+
+    def detection
+      @detection ||=
+        @repository
+        .languages
+        .first(MAX_LANGUAGES)
+        .map { |l| [l[:label], l] }
+        .to_h
+    end
+  end
+end

spec/factories/programming_languages.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :programming_language do
+    name 'Ruby'
+    color '#123456'
+  end
+end

spec/factories/repository_languages.rb

@@ -0,0 +1,7 @@
+FactoryBot.define do
+  factory :repository_language do
+    project
+    programming_language
+    share 98.5
+  end
+end

spec/lib/gitlab/import_export/all_models.yml

@@ -297,6 +297,7 @@ project:
 - settings
 - ci_cd_settings
 - import_export_upload
+- repository_languages
 award_emoji:
 - awardable
 - user

spec/lib/gitlab/language_detection_spec.rb

@@ -0,0 +1,85 @@
+require 'spec_helper'
+
+describe Gitlab::LanguageDetection do
+  set(:project) { create(:project, :repository) }
+  set(:ruby) { create(:programming_language, name: 'Ruby') }
+  set(:haskell) { create(:programming_language, name: 'Haskell') }
+  let(:repository) { project.repository }
+  let(:detection) do
+    [{ value: 66.63, label: "Ruby", color: "#701516", highlight: "#701516" },
+     { value: 12.96, label: "JavaScript", color: "#f1e05a", highlight: "#f1e05a" },
+     { value: 7.9, label: "Elixir", color: "#e34c26", highlight: "#e34c26" },
+     { value: 2.51, label: "CoffeeScript", color: "#244776", highlight: "#244776" },
+     { value: 1.51, label: "Go", color: "#2a4776", highlight: "#244776" },
+     { value: 1.1, label: "MepmepLang", color: "#2a4776", highlight: "#244776" }]
+  end
+  let(:repository_languages) do
+    [RepositoryLanguage.new(share: 10, programming_language: ruby)]
+  end
+
+  subject { described_class.new(repository, repository_languages) }
+
+  before do
+    allow(repository).to receive(:languages).and_return(detection)
+  end
+
+  describe '#languages' do
+    it 'returns the language names' do
+      expect(subject.languages).to eq(%w[Ruby JavaScript Elixir CoffeeScript Go])
+    end
+  end
+
+  describe '#insertions' do
+    let(:programming_languages) { [ruby, haskell] }
+    let(:detection) do
+      [{ value: 10, label: haskell.name, color: haskell.color }]
+    end
+
+    it 'only includes new languages' do
+      insertions = subject.insertions(programming_languages)
+
+      expect(insertions).not_to be_empty
+      expect(insertions.first[:project_id]).to be(project.id)
+      expect(insertions.first[:programming_language_id]).to be(haskell.id)
+      expect(insertions.first[:share]).to be(10)
+    end
+  end
+
+  describe '#updates' do
+    it 'updates the share of languages' do
+      first_update = subject.updates.first
+
+      expect(first_update).not_to be_nil
+      expect(first_update[:programming_language_id]).to eq(ruby.id)
+      expect(first_update[:share]).to eq(66.63)
+    end
+
+    it 'does not include languages to be removed' do
+      ids = subject.updates.map { |h| h[:programming_language_id] }
+
+      expect(ids).not_to include(haskell.id)
+    end
+
+    context 'when silent writes occur' do
+      let(:repository_languages) do
+        [RepositoryLanguage.new(share: 66.63, programming_language: ruby)]
+      end
+
+      it "doesn't include them in the result" do
+        expect(subject.updates).to be_empty
+      end
+    end
+  end
+
+  describe '#deletions' do
+    let(:repository_languages) do
+      [RepositoryLanguage.new(share: 10, programming_language: ruby),
+       RepositoryLanguage.new(share: 5, programming_language: haskell)]
+    end
+
+    it 'lists undetected languages' do
+      expect(subject.deletions).not_to be_empty
+      expect(subject.deletions).to include(haskell.id)
+    end
+  end
+end

spec/models/programming_language_spec.rb

@@ -0,0 +1,11 @@
+require 'spec_helper'
+
+describe ProgrammingLanguage do
+  it { is_expected.to respond_to(:name) }
+  it { is_expected.to respond_to(:color) }
+
+  it { is_expected.to validate_presence_of(:name) }
+  it { is_expected.to allow_value("#000000").for(:color) }
+  it { is_expected.not_to allow_value("000000").for(:color) }
+  it { is_expected.not_to allow_value("#0z0000").for(:color) }
+end

spec/models/project_spec.rb

@@ -69,6 +69,7 @@ describe Project do
     it { is_expected.to have_many(:pages_domains) }
     it { is_expected.to have_many(:labels).class_name('ProjectLabel') }
     it { is_expected.to have_many(:users_star_projects) }
+    it { is_expected.to have_many(:repository_languages) }
     it { is_expected.to have_many(:environments) }
     it { is_expected.to have_many(:deployments) }
     it { is_expected.to have_many(:todos) }

spec/models/repository_language_spec.rb

@@ -0,0 +1,16 @@
+require 'spec_helper'
+
+describe RepositoryLanguage do
+  let(:repository_language) { build(:repository_language) }
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:project) }
+    it { is_expected.to belong_to(:programming_language) }
+  end
+
+  describe 'validations' do
+    it { is_expected.to allow_value(0).for(:share) }
+    it { is_expected.to allow_value(100.0).for(:share) }
+    it { is_expected.not_to allow_value(100.1).for(:share) }
+  end
+end

spec/services/git_push_service_spec.rb

@@ -3,8 +3,8 @@ require 'spec_helper'
 describe GitPushService, services: true do
   include RepoHelpers
 
-  let(:user)     { create(:user) }
-  let(:project)  { create(:project, :repository) }
+  set(:user)     { create(:user) }
+  set(:project)  { create(:project, :repository) }
   let(:blankrev) { Gitlab::Git::BLANK_SHA }
   let(:oldrev)   { sample_commit.parent_id }
   let(:newrev)   { sample_commit.id }

spec/services/projects/detect_repository_languages_service_spec.rb

@@ -0,0 +1,54 @@
+require 'spec_helper'
+
+describe Projects::DetectRepositoryLanguagesService, :clean_gitlab_redis_shared_state do
+  set(:project) { create(:project, :repository) }
+
+  subject { described_class.new(project, project.owner) }
+
+  before do
+    allow(Feature).to receive(:disabled?).and_return(false)
+  end
+
+  describe '#execute' do
+    context 'without previous detection' do
+      it 'inserts new programming languages in the database' do
+        subject.execute
+
+        expect(ProgrammingLanguage.exists?(name: 'Ruby')).to be(true)
+        expect(ProgrammingLanguage.count).to be(4)
+      end
+
+      it 'inserts the repository langauges' do
+        names = subject.execute.map(&:name)
+
+        expect(names).to eq(%w[Ruby JavaScript HTML CoffeeScript])
+      end
+    end
+
+    context 'with a previous detection' do
+      before do
+        subject.execute
+
+        allow(project.repository).to receive(:languages).and_return(
+          [{ value: 99.63, label: "Ruby", color: "#701516", highlight: "#701516" },
+           { value: 0.3, label: "D", color: "#701516", highlight: "#701516" }]
+        )
+      end
+
+      it 'updates the repository languages' do
+        repository_languages = subject.execute.map(&:name)
+
+        expect(repository_languages).to eq(%w[Ruby D])
+      end
+    end
+
+    context 'when no repository exists' do
+      set(:project) { create(:project) }
+
+      it 'has no languages' do
+        expect(subject.execute).to be_empty
+        expect(project.repository_languages).to be_empty
+      end
+    end
+  end
+end

spec/workers/detect_repository_languages_worker_spec.rb

@@ -0,0 +1,32 @@
+require 'spec_helper'
+
+describe DetectRepositoryLanguagesWorker do
+  set(:project) { create(:project) }
+  let(:user) { project.owner }
+
+  subject { described_class.new }
+
+  describe '#perform' do
+    it 'calls de DetectRepositoryLanguages service' do
+      service = double
+      allow(::Projects::DetectRepositoryLanguagesService).to receive(:new).and_return(service)
+      expect(service).to receive(:execute)
+
+      subject.perform(project.id, user.id)
+    end
+
+    context 'when invalid ids are used' do
+      it 'does not raise when the project could not be found' do
+        expect do
+          subject.perform(-1, user.id)
+        end.not_to raise_error
+      end
+
+      it 'does not raise when the user could not be found' do
+        expect do
+          subject.perform(project.id, -1)
+        end.not_to raise_error
+      end
+    end
+  end
+end