Move into proper scopes

This moves the idea of "candidate indexes" into a proper scope on the
model

lib/gitlab/database/postgres_index.rb

@@ -19,7 +19,12 @@ module Gitlab
       end
 
       # Indexes with reindexing support
-      scope :reindexing_support, -> { where(partitioned: false, exclusion: false, expression: false, type: Gitlab::Database::Reindexing::SUPPORTED_TYPES) }
+      scope :reindexing_support, -> do
+        where(partitioned: false, exclusion: false, expression: false, type: Gitlab::Database::Reindexing::SUPPORTED_TYPES)
+          .not_match("#{Gitlab::Database::Reindexing::ReindexConcurrently::TEMPORARY_INDEX_PATTERN}$")
+      end
+
+      scope :reindexing_leftovers, -> { match("#{Gitlab::Database::Reindexing::ReindexConcurrently::TEMPORARY_INDEX_PATTERN}$") }
 
       scope :not_match, ->(regex) { where("name !~ ?", regex) }
 

lib/gitlab/database/reindexing.rb

@@ -14,12 +14,6 @@ module Gitlab
           Coordinator.new(index).perform
         end
       end
-
-      def self.candidate_indexes
-        Gitlab::Database::PostgresIndex
-          .not_match("#{ReindexConcurrently::TEMPORARY_INDEX_PATTERN}$")
-          .reindexing_support
-      end
     end
   end
 end

lib/tasks/gitlab/db.rake

@@ -161,7 +161,7 @@ namespace :gitlab do
         exit
       end
 
-      indexes = Gitlab::Database::Reindexing.candidate_indexes
+      indexes = Gitlab::Database::PostgresIndex.reindexing_support
 
       if identifier = args[:index_name]
         raise ArgumentError, "Index name is not fully qualified with a schema: #{identifier}" unless identifier =~ /^\w+\.\w+$/

spec/lib/gitlab/database/postgres_index_spec.rb

@@ -40,6 +40,37 @@ RSpec.describe Gitlab::Database::PostgresIndex do
 
       expect(types & %w(btree gist)).to eq(types)
     end
+
+    context 'with leftover indexes' do
+      before do
+        ActiveRecord::Base.connection.execute(<<~SQL)
+          CREATE INDEX foobar_ccnew ON users (id);
+          CREATE INDEX foobar_ccnew1 ON users (id);
+        SQL
+      end
+
+      subject { described_class.reindexing_support.map(&:name) }
+
+      it 'excludes temporary indexes from reindexing' do
+        expect(subject).not_to include('foobar_ccnew')
+        expect(subject).not_to include('foobar_ccnew1')
+      end
+    end
+  end
+
+  describe '.reindexing_leftovers' do
+    subject { described_class.reindexing_leftovers }
+
+    before do
+      ActiveRecord::Base.connection.execute(<<~SQL)
+        CREATE INDEX foobar_ccnew ON users (id);
+        CREATE INDEX foobar_ccnew1 ON users (id);
+      SQL
+    end
+
+    it 'retrieves leftover indexes matching the /_ccnew[0-9]*$/ pattern' do
+      expect(subject.map(&:name)).to eq(%w(foobar_ccnew foobar_ccnew1))
+    end
   end
 
   describe '.not_match' do

spec/lib/gitlab/database/reindexing_spec.rb

@@ -25,15 +25,4 @@ RSpec.describe Gitlab::Database::Reindexing do
       subject
     end
   end
-
-  describe '.candidate_indexes' do
-    subject { described_class.candidate_indexes }
-
-    it 'retrieves regular indexes that are no left-overs from previous runs' do
-      result = double
-      expect(Gitlab::Database::PostgresIndex).to receive_message_chain('not_match.reindexing_support').with('\_ccnew[0-9]*$').with(no_args).and_return(result)
-
-      expect(subject).to eq(result)
-    end
-  end
 end

spec/tasks/gitlab/db_rake_spec.rb

@@ -203,7 +203,7 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
 
     context 'when no index_name is given' do
       it 'uses all candidate indexes' do
-        expect(Gitlab::Database::Reindexing).to receive(:candidate_indexes).and_return(indexes)
+        expect(Gitlab::Database::PostgresIndex).to receive(:reindexing_support).and_return(indexes)
         expect(Gitlab::Database::Reindexing).to receive(:perform).with(indexes)
 
         run_rake_task('gitlab:db:reindex')
@@ -214,7 +214,7 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
       let(:index) { double('index') }
 
       before do
-        allow(Gitlab::Database::Reindexing).to receive(:candidate_indexes).and_return(indexes)
+        allow(Gitlab::Database::PostgresIndex).to receive(:reindexing_support).and_return(indexes)
       end
 
       it 'calls the index rebuilder with the proper arguments' do