adds migration that enables a forked project to know where the original project isfork-network

2 files changed, 53 insertions, 1 deletions

diff --git a/db/migrate/20160810165809_add_fork_origin_id_to_projects.rb b/db/migrate/20160810165809_add_fork_origin_id_to_projects.rb
new file mode 100644
index 00000000000..1b1cd287d50
--- /dev/null
+++ b/db/migrate/20160810165809_add_fork_origin_id_to_projects.rb
@@ -0,0 +1,52 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddForkOriginIdToProjects < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+  include Gitlab::Database
+
+  DOWNTIME = true
+
+  class Project < ActiveRecord::Base
+    self.table_name = 'projects'
+  end
+
+  def up
+    add_column :projects, :origin_fork_id, :integer, default: nil, null: true
+
+    transaction do
+      Project.joins('INNER JOIN forked_project_links ON projects.id = forked_project_links.forked_to_project_id')
+             .select('projects.id, forked_project_links.forked_from_project_id').find_in_batches do |rows|
+        forked_origin_ids = {}
+
+        rows.each do |project|
+          origin_fork_id = project.forked_from_project_id
+          next_fork = %Q{SELECT forked_from_project_id FROM forked_project_links WHERE forked_to_project_id = #{origin_fork_id}}
+
+          result = select_all(next_fork)
+          until result.first.nil?
+            if forked_origin_ids.key?(origin_fork_id)
+              origin_fork_id = forked_origin_ids[origin_fork_id]
+              break
+            end
+
+            origin_fork_id = result.first["forked_from_project_id"]
+            result = select_all(next_fork)
+          end
+
+          forked_origin_ids[project.id] = origin_fork_id
+        end
+
+        whens = forked_origin_ids.map do |(project_id, origin_id)|
+          "WHEN id = #{project_id} THEN #{origin_id}"
+        end
+
+        Project.where(id: forked_origin_ids.keys).update_all("origin_fork_id = CASE #{whens.join(' ')} END")
+      end
+    end
+  end
+
+  def down
+    remove_column :projects, :origin_fork_id
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 71980a6d51f..5030119ebac 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160804150737) do
+ActiveRecord::Schema.define(version: 20160810165809) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"