Automatic merge of gitlab-org/gitlab-ce master

app/models/application_record.rb

@@ -6,4 +6,12 @@ class ApplicationRecord < ActiveRecord::Base
   def self.id_in(ids)
     where(id: ids)
   end
+
+  def self.safe_find_or_create_by(*args)
+    transaction(requires_new: true) do
+      find_or_create_by(*args)
+    end
+  rescue ActiveRecord::RecordNotUnique
+    retry
+  end
 end

doc/development/sql.md

@@ -256,32 +256,12 @@ violation, for example.
 
 Using transactions does not solve this problem.
 
-The following pattern should be used to avoid the problem:
+To solve this we've added the `ApplicationRecord.safe_find_or_create_by`.
 
-```ruby
-Project.transaction do
-  begin
-    User.find_or_create_by(username: "foo")
-  rescue ActiveRecord::RecordNotUnique
-    retry
-  end
-end
-```
-
-If the above block is run inside a transaction and hits the race
-condition, the transaction is aborted and we cannot simply retry (any
-further queries inside the aborted transaction are going to fail). We
-can employ [nested transactions](http://api.rubyonrails.org/classes/ActiveRecord/Transactions/ClassMethods.html#module-ActiveRecord::Transactions::ClassMethods-label-Nested+transactions)
-here to only rollback the "inner transaction". Note that `requires_new: true` is required here.
+This method can be used just as you would the normal
+`find_or_create_by` but it wraps the call in a *new* transaction and
+retries if it were to fail because of an
+`ActiveRecord::RecordNotUnique` error.
 
-```ruby
-Project.transaction do
-  begin
-    User.transaction(requires_new: true) do
-      User.find_or_create_by(username: "foo")
-    end
-  rescue ActiveRecord::RecordNotUnique
-    retry
-  end
-end
-```
+To be able to use this method, make sure the model you want to use
+this on inherits from `ApplicationRecord`.

doc/user/project/pages/getting_started_part_two.md

@@ -31,12 +31,26 @@ The optional settings, custom domain, DNS records, and SSL/TLS certificates, are
 ## Project
 
 Your GitLab Pages project is a regular project created the
-same way you do for the other ones. To get started with GitLab Pages, you have two ways:
+same way you do for the other ones. To get started with GitLab Pages, you have three ways:
 
+- Use one of the popular templates already in the app,
 - Fork one of the templates from Page Examples, or
 - Create a new project from scratch
 
-Let's go over both options.
+Let's go over each option.
+
+### Use one of the popular Pages templates bundled with GitLab
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/47857)
+in GitLab 11.8.
+
+The simplest way to create a GitLab Pages site is to use one of the most
+popular templates, which come already bundled and ready to go. To use one
+of these templates:
+
+1. From the top navigation, click the **+** button and select **New project**
+1. Select **Create from Template**
+1. Choose one of the templates starting with **Pages**
 
 ### Fork a project to get started from
 

doc/user/project/pages/index.md

@@ -91,8 +91,8 @@ site under the HTTPS protocol.
 
 ## Getting started
 
-To get started with GitLab Pages, you can either [create a project from scratch](getting_started_part_two.md#create-a-project-from-scratch)
-or quickly start from copying an existing example project, as follows:
+To get started with GitLab Pages, you can either [create a project from scratch](getting_started_part_two.md#create-a-project-from-scratch), 
+use a [bundled template](getting_started_part_two.md#use-one-of-the-popular-pages-templates-bundled-with-gitlab), or copy any of our existing example projects:
 
 1. Choose an [example project](https://gitlab.com/pages) to [fork](../../../gitlab-basics/fork-project.md#how-to-fork-a-project):
    by forking a project, you create a copy of the codebase you're forking from to start from a template instead of starting from scratch.

spec/models/application_record_spec.rb

@@ -10,4 +10,14 @@ describe ApplicationRecord do
       expect(User.id_in(records.last(2).map(&:id))).to eq(records.last(2))
     end
   end
+
+  describe '#safe_find_or_create_by' do
+    it 'creates the user avoiding race conditions' do
+      expect(Suggestion).to receive(:find_or_create_by).and_raise(ActiveRecord::RecordNotUnique)
+      allow(Suggestion).to receive(:find_or_create_by).and_call_original
+
+      expect { Suggestion.safe_find_or_create_by(build(:suggestion).attributes) }
+        .to change { Suggestion.count }.by(1)
+    end
+  end
 end