1 files changed, 31 insertions, 0 deletions
diff --git a/lib/gitlab/database/consistency.rb b/lib/gitlab/database/consistency.rb
new file mode 100644
index 00000000000..b7d06a26ddb
--- /dev/null
+++ b/lib/gitlab/database/consistency.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    ##
+    # This class is used to make it possible to ensure read consistency in
+    # GitLab EE without the need of overriding a lot of methods / classes /
+    # classs.
+    #
+    # This is a CE class that does nothing in CE, because database load
+    # balancing is EE-only feature, but you can still use it in CE. It will
+    # start ensuring read consistency once it is overridden in EE.
+    #
+    # Using this class in CE helps to avoid creeping discrepancy between CE /
+    # EE only to force usage of the primary database in EE.
+    #
+    class Consistency
+      ##
+      # In CE there is no database load balancing, so all reads are expected to
+      # be consistent by the ACID guarantees of a single PostgreSQL instance.
+      #
+      # This method is overridden in EE.
+      #
+      def self.with_read_consistency(&block)
+        yield
+      end
+    end
+  end
+end
+
+::Gitlab::Database::Consistency.singleton_class.prepend_if_ee('EE::Gitlab::Database::Consistency')