1 files changed, 46 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/laziness.rb b/lib/gitlab/graphql/laziness.rb
new file mode 100644
index 00000000000..749d832919d
--- /dev/null
+++ b/lib/gitlab/graphql/laziness.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Graphql
+    # This module allows your class to easily defer and force values.
+    # Its methods are just sugar for calls to the Gitlab::Graphql::Lazy class.
+    #
+    # example:
+    #
+    #  class MyAwesomeClass
+    #    include ::Gitlab::Graphql::Laziness
+    #
+    #    # takes a list of id and list of factors, and computes
+    #    # sum of [SomeObject[i]#value * factor[i]]
+    #    def resolve(ids:, factors:)
+    #      ids.zip(factors)
+    #        .map { |id, factor| promise_an_int(id, factor) }
+    #        .map(&method(:force))
+    #        .sum
+    #    end
+    #
+    #    # returns a promise for an Integer
+    #    def (id, factor)
+    #      thunk = SomeObject.lazy_find(id)
+    #      defer { force(thunk).value * factor }
+    #    end
+    #  end
+    #
+    # In the example above, we use defer to delay forcing the batch-loaded
+    # item until we need it, and then we use `force` to consume the lazy values
+    #
+    # If `SomeObject.lazy_find(id)` batches correctly, calling
+    # `resolve` will only perform one batched load for all objects, rather than
+    # loading them individually before combining the results.
+    #
+    module Laziness
+      def defer(&block)
+        ::Gitlab::Graphql::Lazy.new(&block)
+      end
+
+      def force(lazy)
+        ::Gitlab::Graphql::Lazy.force(lazy)
+      end
+    end
+  end
+end