Timers And Timing Services Overview

Provides timers that asynchronously notify an application after an interval or at a specific time.

Architectural relationships

The User class in the System Static Functions API provides simple functions to suspend a thread for a given interval or until a specific time.


The API has three key concepts: simple timer, periodic timer, and heartbeat timer.

Simple timer

The simple timer produces an event at a given system time or after a given interval. It is provided by RTimer. This service is wrapped in an active object by CTimer.

Periodic timer

A periodic timer produces a sequence of events at a specified interval. The application is called through a callback (TCallBack) when they occur. It is provided by CPeriodic.

Heartbeat timer

A heartbeat timer is similar to a periodic timer. However, if the application is busy handling another event when the timer event occurs, a periodic timer simple delays delivering the event, while a heartbeat timer will inform the application that it has missed the event.

It is provided by CHeartbeat. Applications are alerted to timer events through implementing an interface MBeating.

Related concepts