Add local markdown version

Cached markdown version is composed both from global and local
markdown version. This allows admins to bump version locally when
needed (e.g. when external URL is changed).

17 files changed, 118 insertions, 40 deletions

diff --git a/app/helpers/application_settings_helper.rb b/app/helpers/application_settings_helper.rb
index c8e4e2e3df9..5ba90a272c9 100644
--- a/app/helpers/application_settings_helper.rb
+++ b/app/helpers/application_settings_helper.rb
@@ -231,7 +231,8 @@ module ApplicationSettingsHelper
       :web_ide_clientside_preview_enabled,
       :diff_max_patch_bytes,
       :commit_email_hostname,
-      :protected_ci_variables
+      :protected_ci_variables,
+      :local_markdown_version
     ]
   end
 
diff --git a/app/models/application_setting.rb b/app/models/application_setting.rb
index 88746375c67..c658211d12d 100644
--- a/app/models/application_setting.rb
+++ b/app/models/application_setting.rb
@@ -193,6 +193,10 @@ class ApplicationSetting < ActiveRecord::Base
             allow_nil: true,
             numericality: { only_integer: true, greater_than_or_equal_to: 1.day.seconds }
 
+  validates :local_markdown_version,
+            allow_nil: true,
+            numericality: { only_integer: true, greater_than_or_equal_to: 0, less_than: 65536 }
+
   SUPPORTED_KEY_TYPES.each do |type|
     validates :"#{type}_key_restriction", presence: true, key_restriction: { type: type }
   end
@@ -303,7 +307,8 @@ class ApplicationSetting < ActiveRecord::Base
       usage_stats_set_by_user_id: nil,
       diff_max_patch_bytes: Gitlab::Git::Diff::DEFAULT_MAX_PATCH_BYTES,
       commit_email_hostname: default_commit_email_hostname,
-      protected_ci_variables: false
+      protected_ci_variables: false,
+      local_markdown_version: 0
     }
   end
 
diff --git a/app/models/concerns/cache_markdown_field.rb b/app/models/concerns/cache_markdown_field.rb
index 5fa6f79bdaa..1a8570b80c3 100644
--- a/app/models/concerns/cache_markdown_field.rb
+++ b/app/models/concerns/cache_markdown_field.rb
@@ -115,7 +115,28 @@ module CacheMarkdownField
   end
 
   def latest_cached_markdown_version
-    CacheMarkdownField::CACHE_COMMONMARK_VERSION
+    @latest_cached_markdown_version ||= (CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16) | local_version
+  end
+
+  def local_version
+    # because local_markdown_version is stored in application_settings which
+    # uses cached_markdown_version too, we check explicitly to avoid
+    # endless loop
+    return local_markdown_version if has_attribute?(:local_markdown_version)
+
+    settings = Gitlab::CurrentSettings.current_application_settings
+
+    # Following migrations are not properly isolated and
+    # use real models (by calling .ghost method), in these migrations
+    # local_markdown_version attribute doesn't exist yet, so we
+    # use a default value:
+    # db/migrate/20170825104051_migrate_issues_to_ghost_user.rb
+    # db/migrate/20171114150259_merge_requests_author_id_foreign_key.rb
+    if settings.respond_to?(:local_markdown_version)
+      settings.local_markdown_version
+    else
+      0
+    end
   end
 
   included do
diff --git a/changelogs/unreleased/local-markdown-version-bkp3.yml b/changelogs/unreleased/local-markdown-version-bkp3.yml
new file mode 100644
index 00000000000..ce5bff6ae6b
--- /dev/null
+++ b/changelogs/unreleased/local-markdown-version-bkp3.yml
@@ -0,0 +1,5 @@
+---
+title: Allow admins to invalidate markdown texts by setting local markdown version.
+merge_request:
+author:
+type: added
diff --git a/db/migrate/20190130091630_add_local_cached_markdown_version.rb b/db/migrate/20190130091630_add_local_cached_markdown_version.rb
new file mode 100644
index 00000000000..00570e6458c
--- /dev/null
+++ b/db/migrate/20190130091630_add_local_cached_markdown_version.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class AddLocalCachedMarkdownVersion < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def change
+    add_column :application_settings, :local_markdown_version, :integer, default: 0, null: false
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 4b6e4992056..095c2fbab4a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -168,6 +168,7 @@ ActiveRecord::Schema.define(version: 20190131122559) do
     t.string "commit_email_hostname"
     t.boolean "protected_ci_variables", default: false, null: false
     t.string "runners_registration_token_encrypted"
+    t.integer "local_markdown_version", default: 0, null: false
     t.index ["usage_stats_set_by_user_id"], name: "index_application_settings_on_usage_stats_set_by_user_id", using: :btree
   end
 
diff --git a/doc/administration/index.md b/doc/administration/index.md
index 0b673d61139..38f746ca5bc 100644
--- a/doc/administration/index.md
+++ b/doc/administration/index.md
@@ -64,6 +64,7 @@ Learn how to install, configure, update, and maintain your GitLab instance.
   - [Backup and restore](../raketasks/backup_restore.md): Backup and restore your GitLab instance.
 - [Operations](operations/index.md): Keeping GitLab up and running (clean up Redis sessions, moving repositories, Sidekiq MemoryKiller, Unicorn).
 - [Restart GitLab](restart_gitlab.md): Learn how to restart GitLab and its components.
+- [Invalidate markdown cache](invalidate_markdown_cache.md): Invalidate any cached markdown.
 
 #### Updating GitLab
 
diff --git a/doc/administration/invalidate_markdown_cache.md b/doc/administration/invalidate_markdown_cache.md
new file mode 100644
index 00000000000..ad64cb077c1
--- /dev/null
+++ b/doc/administration/invalidate_markdown_cache.md
@@ -0,0 +1,16 @@
+# Invalidate Markdown Cache
+
+For performance reasons, GitLab caches the HTML version of markdown text
+(e.g. issue and merge request descriptions, comments). It's possible
+that these cached versions become outdated, for example
+when the `external_url` configuration option is changed - causing links
+in the cached text to refer to the old URL.
+
+To avoid this problem, the administrator can invalidate the existing cache by
+increasing the `local_markdown_version` setting in application settings.  This can
+be done by [changing the application settings through
+the API](../api/settings.md#change-application-settings):
+
+```bash
+curl --request PUT --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/application/settings?local_markdown_version=<increased_number>
+```
diff --git a/doc/api/settings.md b/doc/api/settings.md
index c329e3cdf24..287e48c2a42 100644
--- a/doc/api/settings.md
+++ b/doc/api/settings.md
@@ -61,7 +61,8 @@ Example response:
    "terms": "Hello world!",
    "performance_bar_allowed_group_id": 42,
    "instance_statistics_visibility_private": false,
-   "user_show_add_ssh_key_message": true
+   "user_show_add_ssh_key_message": true,
+   "local_markdown_version": 0
 }
 ```
 
@@ -117,7 +118,8 @@ Example response:
   "terms": "Hello world!",
   "performance_bar_allowed_group_id": 42,
   "instance_statistics_visibility_private": false,
-  "user_show_add_ssh_key_message": true
+  "user_show_add_ssh_key_message": true,
+  "local_markdown_version": 0
 }
 ```
 
@@ -235,3 +237,4 @@ are listed in the descriptions of the relevant settings.
 | `user_oauth_applications`                | boolean          | no                                   | Allow users to register any application to use GitLab as an OAuth provider. |
 | `user_show_add_ssh_key_message`          | boolean          | no                                   | When set to `false` disable the "You won't be able to pull or push project code via SSH" warning shown to users with no uploaded SSH key. |
 | `version_check_enabled`                  | boolean          | no                                   | Let GitLab inform you when an update is available. |
+| `local_markdown_version`                 | integer          | no                                   | Increase this value when any cached markdown should be invalidated. |
diff --git a/lib/api/settings.rb b/lib/api/settings.rb
index 95371961398..b16faffe335 100644
--- a/lib/api/settings.rb
+++ b/lib/api/settings.rb
@@ -121,6 +121,7 @@ module API
       optional :terminal_max_session_time, type: Integer, desc: 'Maximum time for web terminal websocket connection (in seconds). Set to 0 for unlimited time.'
       optional :usage_ping_enabled, type: Boolean, desc: 'Every week GitLab will report license usage back to GitLab, Inc.'
       optional :instance_statistics_visibility_private, type: Boolean, desc: 'When set to `true` Instance statistics will only be available to admins'
+      optional :local_markdown_version, type: Integer, desc: "Local markdown version, increase this value when any cached markdown should be invalidated"
 
       ApplicationSetting::SUPPORTED_KEY_TYPES.each do |type|
         optional :"#{type}_key_restriction",
diff --git a/spec/features/snippets/show_spec.rb b/spec/features/snippets/show_spec.rb
index eb974c7c7fd..74fdfcf492e 100644
--- a/spec/features/snippets/show_spec.rb
+++ b/spec/features/snippets/show_spec.rb
@@ -79,14 +79,6 @@ describe 'Snippet', :js do
             expect(page).not_to have_xpath("//ol//li//ul")
           end
         end
-
-        context 'with cached CommonMark html' do
-          let(:snippet) { create(:personal_snippet, :public, file_name: file_name, content: content, cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION) }
-
-          it 'renders correctly' do
-            expect(page).not_to have_xpath("//ol//li//ul")
-          end
-        end
       end
 
       context 'switching to the simple viewer' do
diff --git a/spec/javascripts/notes/mock_data.js b/spec/javascripts/notes/mock_data.js
index 7ae45c40c28..348743081eb 100644
--- a/spec/javascripts/notes/mock_data.js
+++ b/spec/javascripts/notes/mock_data.js
@@ -165,7 +165,6 @@ export const note = {
   report_abuse_path:
     '/abuse_reports/new?ref_url=http%3A%2F%2Flocalhost%3A3000%2Fgitlab-org%2Fgitlab-ce%2Fissues%2F7%23note_546&user_id=1',
   path: '/gitlab-org/gitlab-ce/notes/546',
-  cached_markdown_version: 11,
 };
 
 export const discussionMock = {
diff --git a/spec/lib/banzai/object_renderer_spec.rb b/spec/lib/banzai/object_renderer_spec.rb
index 209a547c3b3..3b52f6666d0 100644
--- a/spec/lib/banzai/object_renderer_spec.rb
+++ b/spec/lib/banzai/object_renderer_spec.rb
@@ -11,7 +11,7 @@ describe Banzai::ObjectRenderer do
     )
   end
 
-  let(:object) { Note.new(note: 'hello', note_html: '<p dir="auto">hello</p>', cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION) }
+  let(:object) { Note.new(note: 'hello', note_html: '<p dir="auto">hello</p>', cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16) }
 
   describe '#render' do
     context 'with cache' do
diff --git a/spec/models/application_setting_spec.rb b/spec/models/application_setting_spec.rb
index 96aa9a82b71..789e14e8a20 100644
--- a/spec/models/application_setting_spec.rb
+++ b/spec/models/application_setting_spec.rb
@@ -70,6 +70,13 @@ describe ApplicationSetting do
         .is_greater_than(0)
     end
 
+    it do
+      is_expected.to validate_numericality_of(:local_markdown_version)
+        .only_integer
+        .is_greater_than_or_equal_to(0)
+        .is_less_than(65536)
+    end
+
     context 'key restrictions' do
       it 'supports all key types' do
         expect(described_class::SUPPORTED_KEY_TYPES).to contain_exactly(:rsa, :dsa, :ecdsa, :ed25519)
diff --git a/spec/models/concerns/cache_markdown_field_spec.rb b/spec/models/concerns/cache_markdown_field_spec.rb
index 29197ef372e..447279f19a8 100644
--- a/spec/models/concerns/cache_markdown_field_spec.rb
+++ b/spec/models/concerns/cache_markdown_field_spec.rb
@@ -60,6 +60,10 @@ describe CacheMarkdownField do
         changes_applied
       end
     end
+
+    def has_attribute?(attr_name)
+      attribute_names.include?(attr_name)
+    end
   end
 
   def thing_subclass(new_attr)
@@ -72,8 +76,8 @@ describe CacheMarkdownField do
   let(:updated_markdown) { '`Bar`' }
   let(:updated_html)     { '<p dir="auto"><code>Bar</code></p>' }
 
-  let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION) }
-  let(:cache_version) { CacheMarkdownField::CACHE_COMMONMARK_VERSION }
+  let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: cache_version) }
+  let(:cache_version) { CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16 }
 
   before do
     stub_commonmark_sourcepos_disabled
@@ -94,11 +98,11 @@ describe CacheMarkdownField do
     it { expect(thing.foo).to eq(markdown) }
     it { expect(thing.foo_html).to eq(html) }
     it { expect(thing.foo_html_changed?).not_to be_truthy }
-    it { expect(thing.cached_markdown_version).to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION) }
+    it { expect(thing.cached_markdown_version).to eq(cache_version) }
   end
 
   context 'a changed markdown field' do
-    let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: cache_version) }
+    let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: cache_version - 1) }
 
     before do
       thing.foo = updated_markdown
@@ -139,7 +143,7 @@ describe CacheMarkdownField do
   end
 
   context 'a non-markdown field changed' do
-    let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: cache_version) }
+    let(:thing) { ThingWithMarkdownFields.new(foo: markdown, foo_html: html, cached_markdown_version: cache_version - 1) }
 
     before do
       thing.bar = 'OK'
@@ -160,7 +164,7 @@ describe CacheMarkdownField do
     end
 
     it { expect(thing.foo_html).to eq(updated_html) }
-    it { expect(thing.cached_markdown_version).to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION) }
+    it { expect(thing.cached_markdown_version).to eq(cache_version) }
   end
 
   describe '#cached_html_up_to_date?' do
@@ -174,21 +178,35 @@ describe CacheMarkdownField do
       is_expected.to be_falsy
     end
 
-    it 'returns false when the version is too early' do
-      thing.cached_markdown_version -= 1
+    it 'returns false when the cached version is too old' do
+      thing.cached_markdown_version = cache_version - 1
 
       is_expected.to be_falsy
     end
 
-    it 'returns false when the version is too late' do
-      thing.cached_markdown_version += 1
+    it 'returns false when the cached version is in future' do
+      thing.cached_markdown_version = cache_version + 1
 
       is_expected.to be_falsy
     end
 
-    it 'returns true when the version is just right' do
+    it 'returns false when the local version was bumped' do
+      allow(Gitlab::CurrentSettings.current_application_settings).to receive(:local_markdown_version).and_return(2)
       thing.cached_markdown_version = cache_version
 
+      is_expected.to be_falsy
+    end
+
+    it 'returns true when the local version is default' do
+      thing.cached_markdown_version = cache_version
+
+      is_expected.to be_truthy
+    end
+
+    it 'returns true when the cached version is just right' do
+      allow(Gitlab::CurrentSettings.current_application_settings).to receive(:local_markdown_version).and_return(2)
+      thing.cached_markdown_version = cache_version + 2
+
       is_expected.to be_truthy
     end
 
@@ -221,14 +239,9 @@ describe CacheMarkdownField do
   describe '#latest_cached_markdown_version' do
     subject { thing.latest_cached_markdown_version }
 
-    it 'returns commonmark version' do
-      thing.cached_markdown_version = CacheMarkdownField::CACHE_COMMONMARK_VERSION_START + 1
-      is_expected.to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION)
-    end
-
-    it 'returns default version when version is nil' do
+    it 'returns default version' do
       thing.cached_markdown_version = nil
-      is_expected.to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION)
+      is_expected.to eq(cache_version)
     end
   end
 
@@ -255,7 +268,7 @@ describe CacheMarkdownField do
       thing.cached_markdown_version = nil
       thing.refresh_markdown_cache
 
-      expect(thing.cached_markdown_version).to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION)
+      expect(thing.cached_markdown_version).to eq(cache_version)
     end
   end
 
@@ -336,7 +349,7 @@ describe CacheMarkdownField do
 
         expect(thing.foo_html).to eq(updated_html)
         expect(thing.baz_html).to eq(updated_html)
-        expect(thing.cached_markdown_version).to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION)
+        expect(thing.cached_markdown_version).to eq(cache_version)
       end
     end
 
@@ -356,7 +369,7 @@ describe CacheMarkdownField do
 
         expect(thing.foo_html).to eq(updated_html)
         expect(thing.baz_html).to eq(updated_html)
-        expect(thing.cached_markdown_version).to eq(CacheMarkdownField::CACHE_COMMONMARK_VERSION)
+        expect(thing.cached_markdown_version).to eq(cache_version)
       end
     end
   end
diff --git a/spec/models/resource_label_event_spec.rb b/spec/models/resource_label_event_spec.rb
index 3797960ac3d..7eeb2fae57d 100644
--- a/spec/models/resource_label_event_spec.rb
+++ b/spec/models/resource_label_event_spec.rb
@@ -81,14 +81,14 @@ RSpec.describe ResourceLabelEvent, type: :model do
       expect(subject.outdated_markdown?).to be true
     end
 
-    it 'returns true markdown is outdated' do
-      subject.attributes = { cached_markdown_version: 0 }
+    it 'returns true if markdown is outdated' do
+      subject.attributes = { cached_markdown_version: ((CacheMarkdownField::CACHE_COMMONMARK_VERSION - 1) << 16) | 0 }
 
       expect(subject.outdated_markdown?).to be true
     end
 
     it 'returns false if label and reference are set' do
-      subject.attributes = { reference: 'whatever', cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION }
+      subject.attributes = { reference: 'whatever', cached_markdown_version: CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16 }
 
       expect(subject.outdated_markdown?).to be false
     end
diff --git a/spec/requests/api/settings_spec.rb b/spec/requests/api/settings_spec.rb
index 45fb1562e84..f33eb5b9e02 100644
--- a/spec/requests/api/settings_spec.rb
+++ b/spec/requests/api/settings_spec.rb
@@ -64,7 +64,8 @@ describe API::Settings, 'Settings' do
             performance_bar_allowed_group_path: group.full_path,
             instance_statistics_visibility_private: true,
             diff_max_patch_bytes: 150_000,
-            default_branch_protection: Gitlab::Access::PROTECTION_DEV_CAN_MERGE
+            default_branch_protection: Gitlab::Access::PROTECTION_DEV_CAN_MERGE,
+            local_markdown_version: 3
           }
 
         expect(response).to have_gitlab_http_status(200)
@@ -90,6 +91,7 @@ describe API::Settings, 'Settings' do
         expect(json_response['instance_statistics_visibility_private']).to be(true)
         expect(json_response['diff_max_patch_bytes']).to eq(150_000)
         expect(json_response['default_branch_protection']).to eq(Gitlab::Access::PROTECTION_DEV_CAN_MERGE)
+        expect(json_response['local_markdown_version']).to eq(3)
       end
     end