delphi中WaitForSingleObject的帮助。
The WaitForSingleObject function returns when one of the following occurs:
?The specified object is in the signaled state.
?The time-out interval elapses.
DWORD WaitForSingleObject(
HANDLE hHandle, // handle of object to wait for
DWORD dwMilliseconds // time-out interval in milliseconds
);
Parameters
hHandle
Identifies the object. For a list of the object types whose handles can be specified,
see the following Remarks section.
Windows NT: The handle must have SYNCHRONIZE access. For more information, see Access
Masks and Access Rights.
dwMilliseconds
Specifies the time-out interval, in milliseconds. The function returns if the interval
elapses, even if the object's state is nonsignaled. If dwMilliseconds is zero, the function tests the object's state and returns immediately. If dwMilliseconds is INFINITE, the function's time-out interval never elapses.
Return Values
If the function succeeds, the return value indicates the event that caused the function
to return.
If the function fails, the return value is WAIT_FAILED. To get extended error information,
call GetLastError.
The return value on success is one of the following values:
Value Meaning
WAIT_ABANDONED 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 is set to nonsignaled.
WAIT_OBJECT_0 The state of the specified object is signaled.
WAIT_TIMEOUT The time-out interval elapsed, and the object's state is nonsignaled.
Remarks
The WaitForSingleObject function checks the current state of the specified object.
If the object's state is nonsignaled, the calling thread enters an efficient wait
state. The thread consumes very little processor time while waiting for the object
state to become signaled or the time-out interval to elapse.
Before returning, a wait function modifies the state of some types of synchronization
objects. Modification occurs only for the object or objects whose signaled state
caused the function to return. For example, the count of a semaphore object is
decreased by one.
The WaitForSingleObject function can wait for the following objects:
Object Description
Change notification The FindFirstChangeNotification function returns the handle.
A change notification object's state is signaled when a specified type of change
occurs within a specified directory or directory tree.
Console input The handle is returned by the CreateFile function when the
CONIN$ value is specified, or by the GetStdHandle function. The object's state is
signaled when there is unread input in the console's input buffer, and it is
nonsignaled when the input buffer is empty.
Event The CreateEvent or OpenEvent function returns the handle. An event object's state is set explicitly to signaled by the SetEvent or PulseEvent function. A manual-reset event object's state must be reset explicitly to nonsignaled by the ResetEvent function. For an auto-reset event object, the wait function resets the object's state to nonsignaled before returning. Event objects are also used in overlapped operations, in which the state is set by the system.
Mutex The CreateMutex or OpenMutex function returns the handle. A mutex object's state is signaled when it is not owned by any thread. The wait function requests ownership of the mutex for the calling thread, changing the mutex's state to nonsignaled when ownership is granted.
Process The CreateProcess or OpenProcess function returns the handle. A process object's state is signaled when the process terminates.
Semaphore The CreateSemaphore or OpenSemaphore function returns the handle. A semaphore object maintains a count between zero and some maximum value. Its state is signaled when its count is greater than zero and nonsignaled when its count is zero. If the current state is signaled, the wait function decreases the count by one.
Thread The CreateProcess, CreateThread, or CreateRemoteThread function returns the handle. A thread object's state is signaled when the thread terminates.
Timer The CreateWaitableTimer or OpenWaitableTimer function returns the handle. Activate the timer by calling the SetWaitableTimer function. The state of an active timer is signaled when it reaches its due time. You can deactivate the timer by calling the CancelWaitableTimer function. The state of an active timer is signaled when it reaches its due time. You can deactivate the timer by calling the CancelWaitableTimer function.
In some circumstances, you can specify a handle of a file, named pipe, or communications
device as a synchronization object in lpHandles. However, their use for this purpose is
discouraged.
You have to be careful when using the wait functions and DDE. If a thread creates any
windows, it must process messages. DDE sends messages to all windows in the system.
If you have a thread that uses a wait function with no time-out interval, the system
will deadlock. Therefore, if you have a thread that creates windows, use MsgWaitForMultipleObjects
or MsgWaitForMultipleObjectsEx, rather than WaitForSingleObject.
从上面可以看出返回值并不是一个消息（我好像还不知道有哪个api的返回值是消息的）
最常用的返回值就是：Wait_Timeout它表明WaitForSingleObject停止等待的的原因是等待
时间片用完。
