1 files changed, 43 insertions, 0 deletions
diff --git a/app/services/projects/count_service.rb b/app/services/projects/count_service.rb
new file mode 100644
index 00000000000..5e633c37bf8
--- /dev/null
+++ b/app/services/projects/count_service.rb
@@ -0,0 +1,43 @@
+module Projects
+  # Base class for the various service classes that count project data (e.g.
+  # issues or forks).
+  class CountService
+    def initialize(project)
+      @project = project
+    end
+
+    def relation_for_count
+      raise(
+        NotImplementedError,
+        '"relation_for_count" must be implemented and return an ActiveRecord::Relation'
+      )
+    end
+
+    def count
+      Rails.cache.fetch(cache_key) { uncached_count }
+    end
+
+    def refresh_cache
+      Rails.cache.write(cache_key, uncached_count)
+    end
+
+    def uncached_count
+      relation_for_count.count
+    end
+
+    def delete_cache
+      Rails.cache.delete(cache_key)
+    end
+
+    def cache_key_name
+      raise(
+        NotImplementedError,
+        '"cache_key_name" must be implemented and return a String'
+      )
+    end
+
+    def cache_key
+      ['projects', @project.id, cache_key_name]
+    end
+  end
+end