1 files changed, 51 insertions, 0 deletions
diff --git a/lib/gitlab/process_memory_cache/helper.rb b/lib/gitlab/process_memory_cache/helper.rb
new file mode 100644
index 00000000000..ee4b81a9a19
--- /dev/null
+++ b/lib/gitlab/process_memory_cache/helper.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Gitlab
+  class ProcessMemoryCache
+    module Helper
+      def fetch_memory_cache(key, &payload)
+        cache = cache_backend.read(key)
+
+        if cache && !stale_cache?(key, cache)
+          cache[:data]
+        else
+          store_cache(key, &payload)
+        end
+      end
+
+      def invalidate_memory_cache(key)
+        touch_cache_timestamp(key)
+      end
+
+      private
+
+      def touch_cache_timestamp(key, time = Time.current.to_f)
+        shared_backend.write(key, time)
+      end
+
+      def stale_cache?(key, cache_info)
+        shared_timestamp = shared_backend.read(key)
+        return true unless shared_timestamp
+
+        shared_timestamp.to_f > cache_info[:cached_at].to_f
+      end
+
+      def store_cache(key)
+        data = yield
+        time = Time.current.to_f
+
+        cache_backend.write(key, data: data, cached_at: time)
+        touch_cache_timestamp(key, time)
+        data
+      end
+
+      def shared_backend
+        Rails.cache
+      end
+
+      def cache_backend
+        ::Gitlab::ProcessMemoryCache.cache_backend
+      end
+    end
+  end
+end