SetWaitableTimer

SetWaitableTimer is a function in the Windows API that creates or opens a timer object. This timer can be used to signal a thread after a specified period or at a specific time. When the timer expires, it signals the specified timer object. This signaling mechanism can be used to wake up a thread that is waiting on the timer object.

The function takes several arguments, including a handle to the timer object, the desired due time, the period of the timer (if it is to repeat), and a callback function to be executed when the timer expires. The due time can be specified as an absolute time or as a relative interval from the current time. The period, if set, determines how often the timer will be re-armed and signaled.

If the timer is set to repeat, it will be signaled repeatedly at the specified interval until it is canceled or closed. The callback function, if provided, is executed in the context of the thread that set the timer. Alternatively, threads can explicitly wait on the timer object using functions like WaitForSingleObject.

SetWaitableTimer is useful for scheduling tasks, implementing time-outs, and creating periodic operations within Windows applications. It provides a flexible way to manage time-based events without requiring a dedicated thread to poll for time. The timer object is a kernel object that can be waited upon by multiple threads. To release the timer object and its associated resources, CloseHandle should be called with the timer handle.