winsvc: retry stop event

Signed-off-by: Daijiro Fukuda <fukuda@clear-code.com>

lib/fluent/winsvc.rb

@@ -63,10 +63,13 @@ def service_main
     end
 
     def service_stop
-      set_event(@service_name)
-      if @pid > 0
-        Process.waitpid(@pid)
+      if @pid <= 0
+        set_event(@service_name)
+        return
       end
+
+      repeat_set_event_several_times_until_success(@service_name)
+      Process.waitpid(@pid)
     end
 
     def service_paramchange
@@ -91,6 +94,24 @@ def set_event(event_name)
       ev.set
       ev.close
     end
+
+    def repeat_set_event_several_times_until_success(event_name)
+      retries = 0
+      max_retries = 10
+      delay_sec = 3
+
+      begin
+        set_event(event_name)
+      rescue Errno::ENOENT
+        # This error occurs when the supervisor process has not yet created the event.
+        # If STOP is immediately executed, this state will occur.
+        # Retry `set_event' to wait for the initilization of the supervisor.
+        retries += 1
+        raise if max_retries < retries
+        sleep(delay_sec)
+        retry
+      end
+    end
   end
 
   FluentdService.new(opts[:service_name]).mainloop