From aldeid
Jump to navigation Jump to search


Waits until the specified object is in the signaled state or the time-out interval elapses.

To enter an alertable wait state, use the WaitForSingleObjectEx function. To wait for multiple objects, use WaitForMultipleObjects.


DWORD WINAPI WaitForSingleObject(
  _In_  HANDLE hHandle,
  _In_  DWORD dwMilliseconds


hHandle [in]
A handle to the object.
If this handle is closed while the wait is still pending, the function's behavior is undefined.
The handle must have the SYNCHRONIZE access right.
dwMilliseconds [in]
The time-out interval, in milliseconds.
If a nonzero value is specified, the function waits until the object is signaled or the interval elapses.
If dwMilliseconds is zero, the function does not enter a wait state if the object is not signaled; it always returns immediately.
If dwMilliseconds is INFINITE, the function will return only when the object is signaled.
The dwMilliseconds value does not include time spent in low-power states. For example, the timeout will not keep counting down while the computer is asleep.

Return value

If the function succeeds, the return value indicates the event that caused the function to return. It can be one of the following values.

Return code/value Description

The specified object is a mutex object that was not released by the thread that owned the mutex object before the owning thread terminated. Ownership of the mutex object is granted to the calling thread and the mutex state is set to nonsignaled.

If the mutex was protecting persistent state information, you should check it for consistency.

The state of the specified object is signaled.
The time-out interval elapsed, and the object's state is nonsignaled.
The function has failed. To get extended error information, call GetLastError