Merge branch 'master' into 41014-bump-svg-version41014-bump-svg-version

* master:
  Docs: add indexes for monitoring and performance monitoring
  clearer-documentation-on-inline-diffs
  Add docs for commit diff discussion in merge requests
  Converted JS modules into exported modules
  Update flipper to 0.11.0 and take advantage of the new features
  Migrate Gitlab::Git::Repository#merge_base_commit to Gitaly

33 files changed, 297 insertions, 236 deletions

diff --git a/GITALY_SERVER_VERSION b/GITALY_SERVER_VERSION
index cb6b534abe1..7e750b4ebf3 100644
--- a/GITALY_SERVER_VERSION
+++ b/GITALY_SERVER_VERSION
@@ -1 +1 @@
-0.59.0
+0.60.0
diff --git a/Gemfile b/Gemfile
index e9701fab27a..06a9b2442af 100644
--- a/Gemfile
+++ b/Gemfile
@@ -400,13 +400,14 @@ group :ed25519 do
 end
 
 # Gitaly GRPC client
-gem 'gitaly-proto', '~> 0.59.0', require: 'gitaly'
+gem 'gitaly-proto', '~> 0.61.0', require: 'gitaly'
 
 gem 'toml-rb', '~> 0.3.15', require: false
 
 # Feature toggles
-gem 'flipper', '~> 0.10.2'
-gem 'flipper-active_record', '~> 0.10.2'
+gem 'flipper', '~> 0.11.0'
+gem 'flipper-active_record', '~> 0.11.0'
+gem 'flipper-active_support_cache_store', '~> 0.11.0'
 
 # Structured logging
 gem 'lograge', '~> 0.5'
diff --git a/Gemfile.lock b/Gemfile.lock
index efae71efdb7..55600555e4d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -215,10 +215,13 @@ GEM
       path_expander (~> 1.0)
       ruby_parser (~> 3.0)
       sexp_processor (~> 4.0)
-    flipper (0.10.2)
-    flipper-active_record (0.10.2)
+    flipper (0.11.0)
+    flipper-active_record (0.11.0)
       activerecord (>= 3.2, < 6)
-      flipper (~> 0.10.2)
+      flipper (~> 0.11.0)
+    flipper-active_support_cache_store (0.11.0)
+      activesupport (>= 3.2, < 6)
+      flipper (~> 0.11.0)
     flowdock (0.7.1)
       httparty (~> 0.7)
       multi_json
@@ -281,7 +284,7 @@ GEM
       po_to_json (>= 1.0.0)
       rails (>= 3.2.0)
     gherkin-ruby (0.3.2)
-    gitaly-proto (0.59.0)
+    gitaly-proto (0.61.0)
       google-protobuf (~> 3.1)
       grpc (~> 1.0)
     github-linguist (4.7.6)
@@ -1021,8 +1024,9 @@ DEPENDENCIES
   faraday (~> 0.12)
   ffaker (~> 2.4)
   flay (~> 2.8.0)
-  flipper (~> 0.10.2)
-  flipper-active_record (~> 0.10.2)
+  flipper (~> 0.11.0)
+  flipper-active_record (~> 0.11.0)
+  flipper-active_support_cache_store (~> 0.11.0)
   fog-aliyun (~> 0.2.0)
   fog-aws (~> 1.4)
   fog-core (~> 1.44)
@@ -1038,7 +1042,7 @@ DEPENDENCIES
   gettext (~> 3.2.2)
   gettext_i18n_rails (~> 1.8.0)
   gettext_i18n_rails_js (~> 1.2.0)
-  gitaly-proto (~> 0.59.0)
+  gitaly-proto (~> 0.61.0)
   github-linguist (~> 4.7.0)
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-markup (~> 1.6.2)
diff --git a/app/assets/javascripts/activities.js b/app/assets/javascripts/activities.js
index d0db7cde262..f5f6b67f26e 100644
--- a/app/assets/javascripts/activities.js
+++ b/app/assets/javascripts/activities.js
@@ -4,7 +4,7 @@
 import Cookies from 'js-cookie';
 import { localTimeAgo } from './lib/utils/datetime_utility';
 
-class Activities {
+export default class Activities {
   constructor() {
     Pager.init(20, true, false, data => data, this.updateTooltips);
 
@@ -34,6 +34,3 @@ class Activities {
     $sender.closest('li').toggleClass('active');
   }
 }
-
-window.gl = window.gl || {};
-window.gl.Activities = Activities;
diff --git a/app/assets/javascripts/admin.js b/app/assets/javascripts/admin.js
index b0b72c40f25..c1f7fa2aced 100644
--- a/app/assets/javascripts/admin.js
+++ b/app/assets/javascripts/admin.js
@@ -1,63 +1,59 @@
-/* eslint-disable func-names, space-before-function-paren, wrap-iife, one-var, no-var, one-var-declaration-per-line, no-unused-vars, no-else-return, prefer-arrow-callback, camelcase, quotes, comma-dangle, max-len */
 import { refreshCurrentPage } from './lib/utils/url_utility';
 
-window.Admin = (function() {
-  function Admin() {
-    var modal, showBlacklistType;
-    $('input#user_force_random_password').on('change', function(elem) {
-      var elems;
-      elems = $('#user_password, #user_password_confirmation');
-      if ($(this).attr('checked')) {
-        return elems.val('').attr('disabled', true);
-      } else {
-        return elems.removeAttr('disabled');
-      }
-    });
-    $('body').on('click', '.js-toggle-colors-link', function(e) {
-      e.preventDefault();
-      return $('.js-toggle-colors-container').toggle();
-    });
-    $('.log-tabs a').click(function(e) {
-      e.preventDefault();
-      return $(this).tab('show');
-    });
-    $('.log-bottom').click(function(e) {
-      var visible_log;
-      e.preventDefault();
-      visible_log = $(".file-content:visible");
-      return visible_log.animate({
-        scrollTop: visible_log.find('ol').height()
-      }, "fast");
-    });
-    modal = $('.change-owner-holder');
-    $('.change-owner-link').bind("click", function(e) {
-      e.preventDefault();
-      $(this).hide();
-      return modal.show();
-    });
-    $('.change-owner-cancel-link').bind("click", function(e) {
-      e.preventDefault();
-      modal.hide();
-      return $('.change-owner-link').show();
-    });
-    $('li.project_member').bind('ajax:success', function() {
-      return refreshCurrentPage();
-    });
-    $('li.group_member').bind('ajax:success', function() {
-      return refreshCurrentPage();
-    });
-    showBlacklistType = function() {
-      if ($("input[name='blacklist_type']:checked").val() === 'file') {
-        $('.blacklist-file').show();
-        return $('.blacklist-raw').hide();
-      } else {
-        $('.blacklist-file').hide();
-        return $('.blacklist-raw').show();
-      }
-    };
-    $("input[name='blacklist_type']").click(showBlacklistType);
-    showBlacklistType();
+function showBlacklistType() {
+  if ($('input[name="blacklist_type"]:checked').val() === 'file') {
+    $('.blacklist-file').show();
+    $('.blacklist-raw').hide();
+  } else {
+    $('.blacklist-file').hide();
+    $('.blacklist-raw').show();
   }
+}
 
-  return Admin;
-})();
+export default function adminInit() {
+  const modal = $('.change-owner-holder');
+
+  $('input#user_force_random_password').on('change', function randomPasswordClick() {
+    const $elems = $('#user_password, #user_password_confirmation');
+    if ($(this).attr('checked')) {
+      $elems.val('').attr('disabled', true);
+    } else {
+      $elems.removeAttr('disabled');
+    }
+  });
+
+  $('body').on('click', '.js-toggle-colors-link', (e) => {
+    e.preventDefault();
+    $('.js-toggle-colors-container').toggle();
+  });
+
+  $('.log-tabs a').on('click', function logTabsClick(e) {
+    e.preventDefault();
+    $(this).tab('show');
+  });
+
+  $('.log-bottom').on('click', (e) => {
+    e.preventDefault();
+    const $visibleLog = $('.file-content:visible');
+    $visibleLog.animate({
+      scrollTop: $visibleLog.find('ol').height(),
+    }, 'fast');
+  });
+
+  $('.change-owner-link').on('click', function changeOwnerLinkClick(e) {
+    e.preventDefault();
+    $(this).hide();
+    modal.show();
+  });
+
+  $('.change-owner-cancel-link').on('click', (e) => {
+    e.preventDefault();
+    modal.hide();
+    $('.change-owner-link').show();
+  });
+
+  $('li.project_member, li.group_member').on('ajax:success', refreshCurrentPage);
+
+  $("input[name='blacklist_type']").on('click', showBlacklistType);
+  showBlacklistType();
+}
diff --git a/app/assets/javascripts/aside.js b/app/assets/javascripts/aside.js
deleted file mode 100644
index 88756884d16..00000000000
--- a/app/assets/javascripts/aside.js
+++ /dev/null
@@ -1,24 +0,0 @@
-/* eslint-disable func-names, space-before-function-paren, wrap-iife, quotes, prefer-arrow-callback, no-var, one-var, one-var-declaration-per-line, no-else-return, max-len */
-
-window.Aside = (function() {
-  function Aside() {
-    $(document).off("click", "a.show-aside");
-    $(document).on("click", 'a.show-aside', function(e) {
-      var btn, icon;
-      e.preventDefault();
-      btn = $(e.currentTarget);
-      icon = btn.find('i');
-      if (icon.hasClass('fa-angle-left')) {
-        btn.parent().find('section').hide();
-        btn.parent().find('aside').fadeIn();
-        return icon.removeClass('fa-angle-left').addClass('fa-angle-right');
-      } else {
-        btn.parent().find('aside').hide();
-        btn.parent().find('section').fadeIn();
-        return icon.removeClass('fa-angle-right').addClass('fa-angle-left');
-      }
-    });
-  }
-
-  return Aside;
-})();
diff --git a/app/assets/javascripts/dispatcher.js b/app/assets/javascripts/dispatcher.js
index 12402fd645f..522f5d12b30 100644
--- a/app/assets/javascripts/dispatcher.js
+++ b/app/assets/javascripts/dispatcher.js
@@ -16,7 +16,7 @@ import BuildArtifacts from './build_artifacts';
 import CILintEditor from './ci_lint_editor';
 import groupsSelect from './groups_select';
 import Search from './search';
-/* global Admin */
+import initAdmin from './admin';
 import NamespaceSelect from './namespace_select';
 import NewCommitForm from './new_commit_form';
 import Project from './project';
@@ -92,6 +92,7 @@ import Diff from './diff';
 import ProjectLabelSubscription from './project_label_subscription';
 import ProjectVariables from './project_variables';
 import SearchAutocomplete from './search_autocomplete';
+import Activities from './activities';
 
 (function() {
   var Dispatcher;
@@ -334,7 +335,7 @@ import SearchAutocomplete from './search_autocomplete';
           shortcut_handler = new ShortcutsIssuable(true);
           break;
         case 'dashboard:activity':
-          new gl.Activities();
+          new Activities();
           break;
         case 'projects:commit:show':
           new Diff();
@@ -355,7 +356,7 @@ import SearchAutocomplete from './search_autocomplete';
           $('.commit-info.branches').load(document.querySelector('.js-commit-box').dataset.commitPath);
           break;
         case 'projects:activity':
-          new gl.Activities();
+          new Activities();
           shortcut_handler = new ShortcutsNavigation();
           break;
         case 'projects:commits:show':
@@ -373,7 +374,7 @@ import SearchAutocomplete from './search_autocomplete';
 
           if ($('#tree-slider').length) new TreeView();
           if ($('.blob-viewer').length) new BlobViewer();
-          if ($('.project-show-activity').length) new gl.Activities();
+          if ($('.project-show-activity').length) new Activities();
           $('#tree-slider').waitForImages(function() {
             ajaxGet(document.querySelector('.js-tree-content').dataset.logsPath);
           });
@@ -407,7 +408,7 @@ import SearchAutocomplete from './search_autocomplete';
           });
           break;
         case 'groups:activity':
-          new gl.Activities();
+          new Activities();
           break;
         case 'groups:show':
           const newGroupChildWrapper = document.querySelector('.js-new-project-subgroup');
@@ -584,7 +585,7 @@ import SearchAutocomplete from './search_autocomplete';
           // needed in rspec
           gl.u2fAuthenticate = u2fAuthenticate;
         case 'admin':
-          new Admin();
+          initAdmin();
           switch (path[1]) {
             case 'broadcast_messages':
               initBroadcastMessagesForm();
diff --git a/app/assets/javascripts/main.js b/app/assets/javascripts/main.js
index f99abeeeb6b..96284c4c168 100644
--- a/app/assets/javascripts/main.js
+++ b/app/assets/javascripts/main.js
@@ -1,6 +1,5 @@
 /* eslint-disable func-names, space-before-function-paren, no-var, quotes, consistent-return, prefer-arrow-callback, comma-dangle, object-shorthand, no-new, max-len, no-multi-spaces, import/newline-after-import, import/first */
 /* global ConfirmDangerModal */
-/* global Aside */
 
 import jQuery from 'jquery';
 import _ from 'underscore';
@@ -37,7 +36,6 @@ import './behaviors/';
 // everything else
 import './activities';
 import './admin';
-import './aside';
 import loadAwardsHandler from './awards_handler';
 import bp from './breakpoints';
 import './confirm_danger_modal';
@@ -273,7 +271,6 @@ $(function () {
     return fitSidebarForSize();
   });
   loadAwardsHandler();
-  new Aside();
 
   renderTimeago();
 
diff --git a/app/assets/javascripts/users/user_tabs.js b/app/assets/javascripts/users/user_tabs.js
index a7046e2f526..992baa9a1ef 100644
--- a/app/assets/javascripts/users/user_tabs.js
+++ b/app/assets/javascripts/users/user_tabs.js
@@ -1,3 +1,4 @@
+import Activities from '../activities';
 import ActivityCalendar from './activity_calendar';
 import { localTimeAgo } from '../lib/utils/datetime_utility';
 
@@ -170,7 +171,7 @@ export default class UserTabs {
     });
 
     // eslint-disable-next-line no-new
-    new gl.Activities();
+    new Activities();
     this.loaded.activity = true;
   }
 
diff --git a/app/assets/stylesheets/framework/mobile.scss b/app/assets/stylesheets/framework/mobile.scss
index 600a1f53b58..a12f28efce6 100644
--- a/app/assets/stylesheets/framework/mobile.scss
+++ b/app/assets/stylesheets/framework/mobile.scss
@@ -111,21 +111,4 @@
   aside:not(.right-sidebar) {
     display: none;
   }
-
-  .show-aside {
-    display: block !important;
-  }
-}
-
-.show-aside {
-  display: none;
-  position: fixed;
-  right: 0;
-  top: 30%;
-  padding: 5px 15px;
-  background: $show-aside-bg;
-  font-size: 20px;
-  color: $show-aside-color;
-  z-index: 100;
-  box-shadow: 0 1px 2px $show-aside-shadow;
 }
diff --git a/app/assets/stylesheets/framework/variables.scss b/app/assets/stylesheets/framework/variables.scss
index 5de5403916f..b84d6c140be 100644
--- a/app/assets/stylesheets/framework/variables.scss
+++ b/app/assets/stylesheets/framework/variables.scss
@@ -245,9 +245,6 @@ $btn-sm-side-margin: 7px;
 $btn-xs-side-margin: 5px;
 $issue-status-expired: $orange-500;
 $issuable-sidebar-color: $gl-text-color-secondary;
-$show-aside-bg: #eee;
-$show-aside-color: #777;
-$show-aside-shadow: #ddd;
 $group-path-color: #999;
 $namespace-kind-color: #aaa;
 $panel-heading-link-color: #777;
diff --git a/app/controllers/projects/merge_requests/creations_controller.rb b/app/controllers/projects/merge_requests/creations_controller.rb
index 1511fc08c89..dc524b790a0 100644
--- a/app/controllers/projects/merge_requests/creations_controller.rb
+++ b/app/controllers/projects/merge_requests/creations_controller.rb
@@ -9,7 +9,10 @@ class Projects::MergeRequests::CreationsController < Projects::MergeRequests::Ap
   before_action :build_merge_request, except: [:create]
 
   def new
-    define_new_vars
+    # n+1: https://gitlab.com/gitlab-org/gitlab-ce/issues/40934
+    Gitlab::GitalyClient.allow_n_plus_1_calls do
+      define_new_vars
+    end
   end
 
   def create
diff --git a/app/models/repository.rb b/app/models/repository.rb
index 0c50d05bd96..552a354d1ce 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -934,7 +934,7 @@ class Repository
   def merge_base(first_commit_id, second_commit_id)
     first_commit_id = commit(first_commit_id).try(:id) || first_commit_id
     second_commit_id = commit(second_commit_id).try(:id) || second_commit_id
-    rugged.merge_base(first_commit_id, second_commit_id)
+    raw_repository.merge_base(first_commit_id, second_commit_id)
   rescue Rugged::ReferenceError
     nil
   end
diff --git a/app/views/shared/_show_aside.html.haml b/app/views/shared/_show_aside.html.haml
deleted file mode 100644
index 3ac9b11b4fa..00000000000
--- a/app/views/shared/_show_aside.html.haml
+++ /dev/null
@@ -1,2 +0,0 @@
-= link_to '#aside', class: 'show-aside' do
-  %i.fa.fa-angle-left
diff --git a/config/initializers/flipper.rb b/config/initializers/flipper.rb
index bfab8c77a4b..cc9167d29b9 100644
--- a/config/initializers/flipper.rb
+++ b/config/initializers/flipper.rb
@@ -1,8 +1,22 @@
-require 'flipper/middleware/memoizer'
+require 'flipper/adapters/active_record'
+require 'flipper/adapters/active_support_cache_store'
 
-unless Rails.env.test?
-  Rails.application.config.middleware.use Flipper::Middleware::Memoizer,
-    lambda { Feature.flipper }
+Flipper.configure do |config|
+  config.default do
+    adapter = Flipper::Adapters::ActiveRecord.new(
+      feature_class: Feature::FlipperFeature, gate_class: Feature::FlipperGate)
+    cached_adapter = Flipper::Adapters::ActiveSupportCacheStore.new(
+      adapter,
+      Rails.cache,
+      expires_in: 10.seconds)
+
+    Flipper.new(cached_adapter)
+  end
+end
 
-  Feature.register_feature_groups
+Feature.register_feature_groups
+
+unless Rails.env.test?
+  require 'flipper/middleware/memoizer'
+  Rails.application.config.middleware.use Flipper::Middleware::Memoizer
 end
diff --git a/doc/administration/index.md b/doc/administration/index.md
index 58922b71ae7..0b199eecefd 100644
--- a/doc/administration/index.md
+++ b/doc/administration/index.md
@@ -106,20 +106,22 @@ server with IMAP authentication on Ubuntu, to be used with Reply by email.
 
 ## Monitoring GitLab
 
-- [Monitoring uptime](../user/admin_area/monitoring/health_check.md): Check the server status using the health check endpoint.
-  - [IP whitelist](monitoring/ip_whitelist.md): Monitor endpoints that provide health check information when probed.
-- [Monitoring GitHub imports](monitoring/github_imports.md): GitLab's GitHub Importer displays Prometheus metrics to monitor the health and progress of the importer.
+- [Monitoring GitLab](monitoring/index.md):
+  - [Monitoring uptime](../user/admin_area/monitoring/health_check.md): Check the server status using the health check endpoint.
+    - [IP whitelist](monitoring/ip_whitelist.md): Monitor endpoints that provide health check information when probed.
+    - [Monitoring GitHub imports](monitoring/github_imports.md): GitLab's GitHub Importer displays Prometheus metrics to monitor the health and progress of the importer.
 - [Conversational Development (ConvDev) Index](../user/admin_area/monitoring/convdev.md): Provides an overview of your entire instance's feature usage.
 
 ### Performance Monitoring
 
-- [GitLab Performance Monitoring](monitoring/performance/gitlab_configuration.md): Enable GitLab Performance Monitoring.
-- [GitLab performance monitoring with InfluxDB](monitoring/performance/introduction.md): Configure GitLab and InfluxDB for measuring performance metrics.
-  - [InfluxDB Schema](monitoring/performance/influxdb_schema.md): Measurements stored in InfluxDB.
-- [GitLab performance monitoring with Prometheus](monitoring/prometheus/index.md): Configure GitLab and Prometheus for measuring performance metrics.
-- [GitLab performance monitoring with Grafana](monitoring/prometheus/index.md): Configure GitLab to visualize time series metrics through graphs and dashboards.
-- [Request Profiling](monitoring/performance/request_profiling.md): Get a detailed profile on slow requests.
-- [Performance Bar](monitoring/performance/performance_bar.md): Get performance information for the current page.
+- [GitLab Performance Monitoring](monitoring/performance/index.md):
+  - [Enable Performance Monitoring](monitoring/performance/gitlab_configuration.md): Enable GitLab Performance Monitoring.
+  - [GitLab performance monitoring with InfluxDB](monitoring/performance/influxdb_configuration.md): Configure GitLab and InfluxDB for measuring performance metrics.
+    - [InfluxDB Schema](monitoring/performance/influxdb_schema.md): Measurements stored in InfluxDB.
+  - [GitLab performance monitoring with Prometheus](monitoring/prometheus/index.md): Configure GitLab and Prometheus for measuring performance metrics.
+  - [GitLab performance monitoring with Grafana](monitoring/performance/grafana_configuration.md): Configure GitLab to visualize time series metrics through graphs and dashboards.
+  - [Request Profiling](monitoring/performance/request_profiling.md): Get a detailed profile on slow requests.
+  - [Performance Bar](monitoring/performance/performance_bar.md): Get performance information for the current page.
 
 ## Troubleshooting
 
diff --git a/doc/administration/monitoring/index.md b/doc/administration/monitoring/index.md
new file mode 100644
index 00000000000..d6333ee62b4
--- /dev/null
+++ b/doc/administration/monitoring/index.md
@@ -0,0 +1,9 @@
+# Monitoring GitLab
+
+Explore our features to monitor your GitLab instance:
+
+- [Performance monitoring](performance/index.md): GitLab Performance Monitoring makes it possible to measure a wide variety of statistics of your instance.
+- [Prometheus](prometheus/index.md): Prometheus is a powerful time-series monitoring service, providing a flexible platform for monitoring GitLab and other software products.
+- [GitHub imports](github_imports.md): Monitor the health and progress of GitLab's GitHub importer with various Prometheus metrics.
+- [Monitoring uptime](../user/admin_area/monitoring/health_check.md): Check the server status using the health check endpoint.
+  - [IP whitelists](ip_whitelist.md): Configure GitLab for monitoring endpoints that provide health check information when probed.
diff --git a/doc/administration/monitoring/performance/index.md b/doc/administration/monitoring/performance/index.md
new file mode 100644
index 00000000000..f5f0363ed38
--- /dev/null
+++ b/doc/administration/monitoring/performance/index.md
@@ -0,0 +1,72 @@
+# GitLab Performance Monitoring
+
+GitLab comes with its own application performance measuring system as of GitLab
+8.4, simply called "GitLab Performance Monitoring". GitLab Performance Monitoring is available in both the
+Community and Enterprise editions.
+
+Apart from this introduction, you are advised to read through the following
+documents in order to understand and properly configure GitLab Performance Monitoring:
+
+- [GitLab Configuration](gitlab_configuration.md)
+- [InfluxDB Install/Configuration](influxdb_configuration.md)
+- [InfluxDB Schema](influxdb_schema.md)
+- [Grafana Install/Configuration](grafana_configuration.md)
+- [Performance bar](performance_bar.md)
+- [Request profiling](request_profiling.md)
+
+>**Note:**
+Omnibus GitLab 8.16 includes Prometheus as an additional tool to collect
+metrics. It will eventually replace InfluxDB when their metrics collection is
+on par. Read more in the [Prometheus documentation](../prometheus/index.md).
+
+## Introduction to GitLab Performance Monitoring
+
+GitLab Performance Monitoring makes it possible to measure a wide variety of statistics
+including (but not limited to):
+
+- The time it took to complete a transaction (a web request or Sidekiq job).
+- The time spent in running SQL queries and rendering HAML views.
+- The time spent executing (instrumented) Ruby methods.
+- Ruby object allocations, and retained objects in particular.
+- System statistics such as the process' memory usage and open file descriptors.
+- Ruby garbage collection statistics.
+
+Metrics data is written to [InfluxDB][influxdb] over [UDP][influxdb-udp]. Stored
+data can be visualized using [Grafana][grafana] or any other application that
+supports reading data from InfluxDB. Alternatively data can be queried using the
+InfluxDB CLI.
+
+## Metric Types
+
+Two types of metrics are collected:
+
+1. Transaction specific metrics.
+1. Sampled metrics, collected at a certain interval in a separate thread.
+
+### Transaction Metrics
+
+Transaction metrics are metrics that can be associated with a single
+transaction. This includes statistics such as the transaction duration, timings
+of any executed SQL queries, time spent rendering HAML views, etc. These metrics
+are collected for every Rack request and Sidekiq job processed.
+
+### Sampled Metrics
+
+Sampled metrics are metrics that can't be associated with a single transaction.
+Examples include garbage collection statistics and retained Ruby objects. These
+metrics are collected at a regular interval. This interval is made up out of two
+parts:
+
+1. A user defined interval.
+1. A randomly generated offset added on top of the interval, the same offset
+   can't be used twice in a row.
+
+The actual interval can be anywhere between a half of the defined interval and a
+half above the interval. For example, for a user defined interval of 15 seconds
+the actual interval can be anywhere between 7.5 and 22.5. The interval is
+re-generated for every sampling run instead of being generated once and re-used
+for the duration of the process' lifetime.
+
+[influxdb]: https://influxdata.com/time-series-platform/influxdb/
+[influxdb-udp]: https://docs.influxdata.com/influxdb/v0.9/write_protocols/udp/
+[grafana]: http://grafana.org/
diff --git a/doc/administration/monitoring/performance/introduction.md b/doc/administration/monitoring/performance/introduction.md
index 17c2b4b70d3..37a5388d2fc 100644
--- a/doc/administration/monitoring/performance/introduction.md
+++ b/doc/administration/monitoring/performance/introduction.md
@@ -1,70 +1 @@
-# GitLab Performance Monitoring
-
-GitLab comes with its own application performance measuring system as of GitLab
-8.4, simply called "GitLab Performance Monitoring". GitLab Performance Monitoring is available in both the
-Community and Enterprise editions.
-
-Apart from this introduction, you are advised to read through the following
-documents in order to understand and properly configure GitLab Performance Monitoring:
-
-- [GitLab Configuration](gitlab_configuration.md)
-- [InfluxDB Install/Configuration](influxdb_configuration.md)
-- [InfluxDB Schema](influxdb_schema.md)
-- [Grafana Install/Configuration](grafana_configuration.md)
-
->**Note:**
-Omnibus GitLab 8.16 includes Prometheus as an additional tool to collect
-metrics. It will eventually replace InfluxDB when their metrics collection is
-on par. Read more in the [Prometheus documentation](../prometheus/index.md).
-
-## Introduction to GitLab Performance Monitoring
-
-GitLab Performance Monitoring makes it possible to measure a wide variety of statistics
-including (but not limited to):
-
-- The time it took to complete a transaction (a web request or Sidekiq job).
-- The time spent in running SQL queries and rendering HAML views.
-- The time spent executing (instrumented) Ruby methods.
-- Ruby object allocations, and retained objects in particular.
-- System statistics such as the process' memory usage and open file descriptors.
-- Ruby garbage collection statistics.
-
-Metrics data is written to [InfluxDB][influxdb] over [UDP][influxdb-udp]. Stored
-data can be visualized using [Grafana][grafana] or any other application that
-supports reading data from InfluxDB. Alternatively data can be queried using the
-InfluxDB CLI.
-
-## Metric Types
-
-Two types of metrics are collected:
-
-1. Transaction specific metrics.
-1. Sampled metrics, collected at a certain interval in a separate thread.
-
-### Transaction Metrics
-
-Transaction metrics are metrics that can be associated with a single
-transaction. This includes statistics such as the transaction duration, timings
-of any executed SQL queries, time spent rendering HAML views, etc. These metrics
-are collected for every Rack request and Sidekiq job processed.
-
-### Sampled Metrics
-
-Sampled metrics are metrics that can't be associated with a single transaction.
-Examples include garbage collection statistics and retained Ruby objects. These
-metrics are collected at a regular interval. This interval is made up out of two
-parts:
-
-1. A user defined interval.
-1. A randomly generated offset added on top of the interval, the same offset
-   can't be used twice in a row.
-
-The actual interval can be anywhere between a half of the defined interval and a
-half above the interval. For example, for a user defined interval of 15 seconds
-the actual interval can be anywhere between 7.5 and 22.5. The interval is
-re-generated for every sampling run instead of being generated once and re-used
-for the duration of the process' lifetime.
-
-[influxdb]: https://influxdata.com/time-series-platform/influxdb/
-[influxdb-udp]: https://docs.influxdata.com/influxdb/v0.9/write_protocols/udp/
-[grafana]: http://grafana.org/
+This document was moved to [another location](index.md).
diff --git a/doc/development/performance.md b/doc/development/performance.md
index 04419650b12..e7c5a6ca07a 100644
--- a/doc/development/performance.md
+++ b/doc/development/performance.md
@@ -37,7 +37,7 @@ graphs/dashboards.
 GitLab provides built-in tools to aid the process of improving performance:
 
 * [Sherlock](profiling.md#sherlock)
-* [GitLab Performance Monitoring](../administration/monitoring/performance/introduction.md)
+* [GitLab Performance Monitoring](../administration/monitoring/performance/index.md)
 * [Request Profiling](../administration/monitoring/performance/request_profiling.md)
 * [QueryRecoder](query_recorder.md) for preventing `N+1` regressions
 
diff --git a/doc/monitoring/performance/introduction.md b/doc/monitoring/performance/introduction.md
index ae88baa0c14..4d6f02b6547 100644
--- a/doc/monitoring/performance/introduction.md
+++ b/doc/monitoring/performance/introduction.md
@@ -1 +1 @@
-This document was moved to [administration/monitoring/performance/introduction](../../administration/monitoring/performance/introduction.md).
+This document was moved to [administration/monitoring/performance/introduction](../../administration/monitoring/performance/index.md).
diff --git a/doc/user/discussions/img/commit_comment_mr_context.png b/doc/user/discussions/img/commit_comment_mr_context.png
new file mode 100644
index 00000000000..b363e0035e8
--- /dev/null
+++ b/doc/user/discussions/img/commit_comment_mr_context.png
diff --git a/doc/user/discussions/img/commit_comment_mr_discussions_tab.png b/doc/user/discussions/img/commit_comment_mr_discussions_tab.png
new file mode 100644
index 00000000000..2b06cdcc055
--- /dev/null
+++ b/doc/user/discussions/img/commit_comment_mr_discussions_tab.png
diff --git a/doc/user/discussions/img/merge_request_commits_tab.png b/doc/user/discussions/img/merge_request_commits_tab.png
new file mode 100644
index 00000000000..41a3648f390
--- /dev/null
+++ b/doc/user/discussions/img/merge_request_commits_tab.png
diff --git a/doc/user/discussions/index.md b/doc/user/discussions/index.md
index 2206b2860f4..eacfe2baa27 100644
--- a/doc/user/discussions/index.md
+++ b/doc/user/discussions/index.md
@@ -32,6 +32,43 @@ hide discussions that are no longer relevant.
 Comments and discussions can be resolved by anyone with at least Developer
 access to the project or the author of the merge request.
 
+### Commit discussions in the context of a merge request
+
+> [Introduced][ce-31847] in GitLab 10.3.
+
+For reviewers with commit-based workflow, it may be useful to add discussions to
+specific commit diffs in the context of a merge request. These discussions will
+persist through a commit ID change when:
+
+- force-pushing after a rebase
+- amending a commit
+
+To create a commit diff discussion:
+
+1. Navigate to the merge request **Commits** tab. A list of commits that
+   constitute the merge request will be shown.
+
+    ![Merge request commits tab](img/merge_request_commits_tab.png)
+
+1. Navigate to a specific commit, click on the **Changes** tab (where you
+   will only be presented diffs from the selected commit), and leave a comment.
+
+    ![Commit diff discussion in merge request context](img/commit_comment_mr_context.png)
+
+1. Any discussions created this way will be shown in the merge request's
+   **Discussions** tab and are resolvable.
+
+    ![Merge request Discussions tab](img/commit_comment_mr_discussions_tab.png)
+
+Discussions created this way will only appear in the original merge request
+and not when navigating to that commit under your project's
+**Repository > Commits** page.
+
+TIP: **Tip:**
+When a link of a commit reference is found in a discussion inside a merge
+request, it will be automatically converted to a link in the context of the
+current merge request.
+
 ### Jumping between unresolved discussions
 
 When a merge request has a large number of comments it can be difficult to track
@@ -133,6 +170,15 @@ From now on, any discussions on a diff will be resolved by default if a push
 makes that diff section outdated. Discussions on lines that don't change and
 top-level resolvable discussions are not automatically resolved.
 
+## Commit discussions
+
+You can add comments and discussion threads to a particular commit under your
+project's **Repository > Commits**.
+
+CAUTION: **Attention:**
+Discussions created this way will be lost if the commit ID changes after a
+force push.
+
 ## Threaded discussions
 
 > [Introduced][ce-7527] in GitLab 9.1.
@@ -229,6 +275,7 @@ edit existing comments. Non-team members are restricted from adding or editing c
 [ce-14053]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14053
 [ce-14061]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14061
 [ce-14531]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14531
+[ce-31847]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31847
 [resolve-discussion-button]: img/resolve_discussion_button.png
 [resolve-comment-button]: img/resolve_comment_button.png
 [discussion-view]: img/discussion_view.png
diff --git a/doc/user/markdown.md b/doc/user/markdown.md
index a671c92640a..552abac747b 100644
--- a/doc/user/markdown.md
+++ b/doc/user/markdown.md
@@ -195,12 +195,23 @@ With inline diffs tags you can display {+ additions +} or [- deletions -].
 
 The wrapping tags can be either curly braces or square brackets [+ additions +] or {- deletions -}.
 
+Examples:
+
+```
+- {+ additions +}
+- [+ additions +]
+- {- deletions -}
+- [- deletions -]
+```
+
 However the wrapping tags cannot be mixed as such:
 
+```
 - {+ additions +]
 - [+ additions +}
 - {- deletions -]
 - [- deletions -}
+```
 
 ### Emoji
 
diff --git a/lib/feature.rb b/lib/feature.rb
index ac3bc65c0d5..8e9ba5c530a 100644
--- a/lib/feature.rb
+++ b/lib/feature.rb
@@ -1,5 +1,3 @@
-require 'flipper/adapters/active_record'
-
 class Feature
   # Classes to override flipper table names
   class FlipperFeature < Flipper::Adapters::ActiveRecord::Feature
@@ -62,12 +60,7 @@ class Feature
     end
 
     def flipper
-      @flipper ||= begin
-        adapter = Flipper::Adapters::ActiveRecord.new(
-          feature_class: FlipperFeature, gate_class: FlipperGate)
-
-        Flipper.new(adapter)
-      end
+      @flipper ||= Flipper.instance
     end
 
     # This method is called from config/initializers/flipper.rb and can be used
diff --git a/lib/gitlab/git/operation_service.rb b/lib/gitlab/git/operation_service.rb
index 7e8fe173056..ef5bdbaf819 100644
--- a/lib/gitlab/git/operation_service.rb
+++ b/lib/gitlab/git/operation_service.rb
@@ -126,7 +126,7 @@ module Gitlab
 
         oldrev = branch.target
 
-        if oldrev == repository.rugged.merge_base(newrev, branch.target)
+        if oldrev == repository.merge_base(newrev, branch.target)
           oldrev
         else
           raise Gitlab::Git::CommitError.new('Branch diverged')
diff --git a/lib/gitlab/git/repository.rb b/lib/gitlab/git/repository.rb
index 0e0a1987c7d..369bb16f719 100644
--- a/lib/gitlab/git/repository.rb
+++ b/lib/gitlab/git/repository.rb
@@ -517,8 +517,15 @@ module Gitlab
 
       # Returns the SHA of the most recent common ancestor of +from+ and +to+
       def merge_base_commit(from, to)
-        rugged.merge_base(from, to)
+        gitaly_migrate(:merge_base) do |is_enabled|
+          if is_enabled
+            gitaly_repository_client.find_merge_base(from, to)
+          else
+            rugged.merge_base(from, to)
+          end
+        end
       end
+      alias_method :merge_base, :merge_base_commit
 
       # Gitaly note: JV: check gitlab-ee before removing this method.
       def rugged_is_ancestor?(ancestor_id, descendant_id)
diff --git a/lib/gitlab/gitaly_client/repository_service.rb b/lib/gitlab/gitaly_client/repository_service.rb
index a477d618f63..c1f95396878 100644
--- a/lib/gitlab/gitaly_client/repository_service.rb
+++ b/lib/gitlab/gitaly_client/repository_service.rb
@@ -69,6 +69,16 @@ module Gitlab
         response.value
       end
 
+      def find_merge_base(*revisions)
+        request = Gitaly::FindMergeBaseRequest.new(
+          repository: @gitaly_repo,
+          revisions: revisions.map { |r| GitalyClient.encode(r) }
+        )
+
+        response = GitalyClient.call(@storage, :repository_service, :find_merge_base, request)
+        response.base.presence
+      end
+
       def fetch_source_branch(source_repository, source_branch, local_ref)
         request = Gitaly::FetchSourceBranchRequest.new(
           repository: @gitaly_repo,
diff --git a/spec/fixtures/markdown.md.erb b/spec/fixtures/markdown.md.erb
index 638cd8b07c8..71abb6da607 100644
--- a/spec/fixtures/markdown.md.erb
+++ b/spec/fixtures/markdown.md.erb
@@ -258,12 +258,23 @@ With inline diffs tags you can display {+ additions +} or [- deletions -].
 
 The wrapping tags can be either curly braces or square brackets [+ additions +] or {- deletions -}.
 
-However the wrapping tags can not be mixed as such -
+Examples:
 
+```
+- {+ additions +}
+- [+ additions +]
+- {- deletions -}
+- [- deletions -]
+```
+
+However the wrapping tags cannot be mixed as such:
+
+```
 - {+ additions +]
 - [+ additions +}
-- {- delletions -]
-- [- delletions -}
+- {- deletions -]
+- [- deletions -}
+```
 
 ### Videos
 
diff --git a/spec/javascripts/activities_spec.js b/spec/javascripts/activities_spec.js
index e8c5f721423..fc9be14df8f 100644
--- a/spec/javascripts/activities_spec.js
+++ b/spec/javascripts/activities_spec.js
@@ -2,7 +2,7 @@
 
 import 'vendor/jquery.endless-scroll';
 import '~/pager';
-import '~/activities';
+import Activities from '~/activities';
 
 (() => {
   window.gon || (window.gon = {});
@@ -35,7 +35,7 @@ import '~/activities';
   describe('Activities', () => {
     beforeEach(() => {
       loadFixtures(fixtureTemplate);
-      new gl.Activities();
+      new Activities();
     });
 
     for (let i = 0; i < filters.length; i += 1) {
diff --git a/spec/models/repository_spec.rb b/spec/models/repository_spec.rb
index f0661b0a972..799d99c0369 100644
--- a/spec/models/repository_spec.rb
+++ b/spec/models/repository_spec.rb
@@ -1013,7 +1013,7 @@ describe Repository do
 
       it 'runs without errors' do
         # old_rev is an ancestor of new_rev
-        expect(repository.rugged.merge_base(old_rev, new_rev)).to eq(old_rev)
+        expect(repository.merge_base(old_rev, new_rev)).to eq(old_rev)
 
         # old_rev is not a direct ancestor (parent) of new_rev
         expect(repository.rugged.lookup(new_rev).parent_ids).not_to include(old_rev)
@@ -1035,7 +1035,7 @@ describe Repository do
 
       it 'raises an exception' do
         # The 'master' branch is NOT an ancestor of new_rev.
-        expect(repository.rugged.merge_base(old_rev, new_rev)).not_to eq(old_rev)
+        expect(repository.merge_base(old_rev, new_rev)).not_to eq(old_rev)
 
         # Updating 'master' to new_rev would lose the commits on 'master' that
         # are not contained in new_rev. This should not be allowed.