Merge branch 'dz-nested-groups' into 'master'

Add nested groups support on data level

## What does this MR do?

- [x] Add  `parent_id` field to `Namespace`model. 
- [x] Create new database table `routes` that keeps information about full path to each group or project
- [x] Remove uniq index from `namespaces.path`
- [x] Add uniq index on `routes.path`
- [x] Fill routes table with path data from namespaces and projects
- [x] Change Namespace/Project URL lookup by routes table
- [x] Rename related routes (nested groups, projects) when parent path changes

This is solely backend preparation. UI, Permissions and API support will be added in separate merge request.   
 
## Are there points in the code the reviewer needs to double check?

migrations, Route model, Routable concern

Will require downtime. See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7121#note_19490281 discussion

## Why was this MR needed?

One step further to full nested groups support

## Screenshots (if relevant)

No UI changes in this merge request so far

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG.md) entry added~~
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/2772

See merge request !7121

1 files changed, 13 insertions, 84 deletions

diff --git a/app/models/project.rb b/app/models/project.rb
index 590885c0177..77d740081c6 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -14,6 +14,7 @@ class Project < ActiveRecord::Base
   include TokenAuthenticatable
   include ProjectFeaturesCompatibility
   include SelectForProjectAuthorization
+  include Routable
 
   extend Gitlab::ConfigHelper
 
@@ -324,87 +325,6 @@ class Project < ActiveRecord::Base
       non_archived.where(table[:name].matches(pattern))
     end
 
-    # Finds a single project for the given path.
-    #
-    # path - The full project path (including namespace path).
-    #
-    # Returns a Project, or nil if no project could be found.
-    def find_with_namespace(path)
-      namespace_path, project_path = path.split('/', 2)
-
-      return unless namespace_path && project_path
-
-      namespace_path = connection.quote(namespace_path)
-      project_path = connection.quote(project_path)
-
-      # On MySQL we want to ensure the ORDER BY uses a case-sensitive match so
-      # any literal matches come first, for this we have to use "BINARY".
-      # Without this there's still no guarantee in what order MySQL will return
-      # rows.
-      binary = Gitlab::Database.mysql? ? 'BINARY' : ''
-
-      order_sql = "(CASE WHEN #{binary} namespaces.path = #{namespace_path} " \
-        "AND #{binary} projects.path = #{project_path} THEN 0 ELSE 1 END)"
-
-      where_paths_in([path]).reorder(order_sql).take
-    end
-
-    # Builds a relation to find multiple projects by their full paths.
-    #
-    # Each path must be in the following format:
-    #
-    #     namespace_path/project_path
-    #
-    # For example:
-    #
-    #     gitlab-org/gitlab-ce
-    #
-    # Usage:
-    #
-    #     Project.where_paths_in(%w{gitlab-org/gitlab-ce gitlab-org/gitlab-ee})
-    #
-    # This would return the projects with the full paths matching the values
-    # given.
-    #
-    # paths - An Array of full paths (namespace path + project path) for which
-    #         to find the projects.
-    #
-    # Returns an ActiveRecord::Relation.
-    def where_paths_in(paths)
-      wheres = []
-      cast_lower = Gitlab::Database.postgresql?
-
-      paths.each do |path|
-        namespace_path, project_path = path.split('/', 2)
-
-        next unless namespace_path && project_path
-
-        namespace_path = connection.quote(namespace_path)
-        project_path = connection.quote(project_path)
-
-        where = "(namespaces.path = #{namespace_path}
-          AND projects.path = #{project_path})"
-
-        if cast_lower
-          where = "(
-            #{where}
-            OR (
-              LOWER(namespaces.path) = LOWER(#{namespace_path})
-              AND LOWER(projects.path) = LOWER(#{project_path})
-            )
-          )"
-        end
-
-        wheres << where
-      end
-
-      if wheres.empty?
-        none
-      else
-        joins(:namespace).where(wheres.join(' OR '))
-      end
-    end
-
     def visibility_levels
       Gitlab::VisibilityLevel.options
     end
@@ -440,6 +360,10 @@ class Project < ActiveRecord::Base
     def group_ids
       joins(:namespace).where(namespaces: { type: 'Group' }).select(:namespace_id)
     end
+
+    # Add alias for Routable method for compatibility with old code.
+    # In future all calls `find_with_namespace` should be replaced with `find_by_full_path`
+    alias_method :find_with_namespace, :find_by_full_path
   end
 
   def lfs_enabled?
@@ -879,13 +803,14 @@ class Project < ActiveRecord::Base
   end
   alias_method :human_name, :name_with_namespace
 
-  def path_with_namespace
-    if namespace
-      namespace.path + '/' + path
+  def full_path
+    if namespace && path
+      namespace.full_path + '/' + path
     else
       path
     end
   end
+  alias_method :path_with_namespace, :full_path
 
   def execute_hooks(data, hooks_scope = :push_hooks)
     hooks.send(hooks_scope).each do |hook|
@@ -1373,4 +1298,8 @@ class Project < ActiveRecord::Base
   def validate_board_limit(board)
     raise BoardLimitExceeded, 'Number of permitted boards exceeded' if boards.size >= NUMBER_OF_PERMITTED_BOARDS
   end
+
+  def full_path_changed?
+    path_changed? || namespace_id_changed?
+  end
 end