Fix bug where destroying a namespace would not always destroy projects

There is a race condition in DestroyGroupService now that projects are deleted asynchronously:

1. User attempts to delete group
2. DestroyGroupService iterates through all projects and schedules a Sidekiq job to delete each Project
3. DestroyGroupService destroys the Group, leaving all its projects without a namespace
4. Projects::DestroyService runs later but the can?(current_user,
   :remove_project) is `false` because the user no longer has permission to
   destroy projects with no namespace.
5. This leaves the project in pending_delete state with no namespace/group.

Projects without a namespace or group also adds another problem: it's not possible to destroy the container
registry tags, since container_registry_path_with_namespace is the wrong value.

The fix is to destroy the group asynchronously and to run execute directly on Projects::DestroyService.

Closes #17893

3 files changed, 22 insertions, 2 deletions

diff --git a/db/migrate/20140407135544_fix_namespaces.rb b/db/migrate/20140407135544_fix_namespaces.rb
index 91374966698..0026ce645a6 100644
--- a/db/migrate/20140407135544_fix_namespaces.rb
+++ b/db/migrate/20140407135544_fix_namespaces.rb
@@ -1,8 +1,14 @@
 # rubocop:disable all
 class FixNamespaces < ActiveRecord::Migration
+  DOWNTIME = false
+
   def up
-    Namespace.where('name <> path and type is null').each do |namespace|
-      namespace.update_attribute(:name, namespace.path)
+    namespaces = exec_query('SELECT id, path FROM namespaces WHERE name <> path and type is null')
+
+    namespaces.each do |row|
+      id = row['id']
+      path = row['path']
+      exec_query("UPDATE namespaces SET name = '#{path}' WHERE id = #{id}")
     end
   end
 
diff --git a/db/migrate/20160805041956_add_deleted_at_to_namespaces.rb b/db/migrate/20160805041956_add_deleted_at_to_namespaces.rb
new file mode 100644
index 00000000000..a853de3abfb
--- /dev/null
+++ b/db/migrate/20160805041956_add_deleted_at_to_namespaces.rb
@@ -0,0 +1,12 @@
+class AddDeletedAtToNamespaces < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def change
+    add_column :namespaces, :deleted_at, :datetime
+    add_concurrent_index :namespaces, :deleted_at
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 6c85e1e9dba..1de2cdcf026 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -640,9 +640,11 @@ ActiveRecord::Schema.define(version: 20160810142633) do
     t.boolean  "share_with_group_lock",  default: false
     t.integer  "visibility_level",       default: 20,    null: false
     t.boolean  "request_access_enabled", default: true,  null: false
+    t.datetime "deleted_at"
   end
 
   add_index "namespaces", ["created_at"], name: "index_namespaces_on_created_at", using: :btree
+  add_index "namespaces", ["deleted_at"], name: "index_namespaces_on_deleted_at", using: :btree
   add_index "namespaces", ["name"], name: "index_namespaces_on_name", unique: true, using: :btree
   add_index "namespaces", ["name"], name: "index_namespaces_on_name_trigram", using: :gin, opclasses: {"name"=>"gin_trgm_ops"}
   add_index "namespaces", ["owner_id"], name: "index_namespaces_on_owner_id", using: :btree