4.17 WFSAsyncLock

HRESULT WFSAsyncLock( hService, dwTimeOut, hWnd, lpRequestID )

Establishes exclusive control by the calling application over the specified service. The asynchronous version of WFSLock.

Parameters HSERVICE hService

Handle to the service provider as returned by WFSOpen or WFSAsyncOpen.

DWORD dwTimeOut

Number of milliseconds to wait for completion (WFS_INDEFINITE_WAIT to specify a request that will wait until completion).

HWND hWnd

The window handle which is to receive the completion message for this request.

LPREQUESTID lpRequestID

Pointer to the request identifier for this request (returned parameter).

Mode Asynchronous

Comments See WFSLock and Section 3.8.2. In particular, note that if other services are locked as a result of this call (i.e., because the service specified is part of a compound device), the handles of these services are returned in the WFSRESULT data structure pointed to by the completion message.

The application must call WFSFreeResult to deallocate the WFSRESULT data structure. Note that a WFSRESULT structure may be returned even if the function completes with an error; see Section 3.13.

Messages WFS_LOCK_COMPLETE

Error Codes If the function return is not WFS_SUCCESS, it is one of the following error conditions, indicating that the asynchronous operation was not initiated:

WFS_ERR_CONNECTION_LOST

The connection to the service is lost.

WFS_ERR_INTERNAL_ERROR

An internal inconsistency or other unexpected error occurred in the WOSA/XFS subsystem.

WFS_ERR_INVALID_HSERVICE

The hService parameter is not a valid service handle.

WFS_ERR_INVALID_HWND

The hWnd parameter is not a valid window handle.

WFS_ERR_INVALID_POINTER

A pointer parameter does not point to accessible memory.

WFS_ERR_NOT_STARTED

The application has not previously performed a successful WFSStartUp.

WFS_ERR_OP_IN_PROGRESS

A blocking operation is in progress on the thread; only WFSCancelBlockingCall and WFSIsBlocking are permitted at this time.

The following error conditions are returned via the asynchronous command completion message, as the hResult from the WFSRESULT structure.

WFS_ERR_CANCELED

The request was canceled by WFSCancelAsyncRequest.

WFS_ERR_INTERNAL_ERROR

An internal inconsistency or other unexpected error occurred in the WOSA/XFS subsystem.

WFS_ERR_TIMEOUT

The timeout interval expired.

See also WFSLock, WFSUnlock, WFSCancelAsyncRequest