1 files changed, 63 insertions, 0 deletions
diff --git a/lib/gitlab/daemon.rb b/lib/gitlab/daemon.rb
new file mode 100644
index 00000000000..633de9f9776
--- /dev/null
+++ b/lib/gitlab/daemon.rb
@@ -0,0 +1,63 @@
+module Gitlab
+  class Daemon
+    def self.initialize_instance(*args)
+      raise "#{name} singleton instance already initialized" if @instance
+
+      @instance = new(*args)
+      Kernel.at_exit(&@instance.method(:stop))
+      @instance
+    end
+
+    def self.instance
+      @instance ||= initialize_instance
+    end
+
+    attr_reader :thread
+
+    def thread?
+      !thread.nil?
+    end
+
+    def initialize
+      @mutex = Mutex.new
+    end
+
+    def enabled?
+      true
+    end
+
+    def start
+      return unless enabled?
+
+      @mutex.synchronize do
+        return thread if thread?
+
+        @thread = Thread.new { start_working }
+      end
+    end
+
+    def stop
+      @mutex.synchronize do
+        return unless thread?
+
+        stop_working
+
+        if thread
+          thread.wakeup if thread.alive?
+          thread.join unless Thread.current == thread
+          @thread = nil
+        end
+      end
+    end
+
+    private
+
+    def start_working
+      raise NotImplementedError
+    end
+
+    def stop_working
+      # no-ops
+    end
+  end
+end