+local function add_task(delay, callback)
+ local event_handle;
+ event_handle = base:addevent(nil, 0, function ()
+ local ret = callback(socket_gettime());
+ if ret then
+ return 0, ret;
+ elseif event_handle then
+ return -1;
+ end
+ end
+ , delay);
+ return event_handle;
+end
+