WSACancelAsyncRequest function (winsock.h)
The WSACancelAsyncRequest function cancels an incomplete asynchronous operation.
int WSACancelAsyncRequest( HANDLE hAsyncTaskHandle );
Handle that specifies the asynchronous operation to be canceled.
The value returned by WSACancelAsyncRequest is zero if the operation was successfully canceled. Otherwise, the value SOCKET_ERROR is returned, and a specific error number can be retrieved by calling WSAGetLastError.
|A successful WSAStartup call must occur before using this function.|
|The network subsystem has failed.|
|Indicates that the specified asynchronous task handle was invalid.|
|A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.|
|The asynchronous routine being canceled has already completed.|
The WSACancelAsyncRequest function is used to cancel an asynchronous operation that was initiated by one of the WSAAsyncGetXByY functions such as WSAAsyncGetHostByName. The operation to be canceled is identified by the hAsyncTaskHandle parameter, which should be set to the asynchronous task handle as returned by the initiating WSAAsyncGetXByY function.
An attempt to cancel an existing asynchronous WSAAsyncGetXByY operation can fail with an error code of WSAEALREADY for two reasons. First, the original operation has already completed and the application has dealt with the resultant message. Second, the original operation has already completed but the resultant message is still waiting in the application window queue.
|Minimum supported client||Windows 2000 Professional [desktop apps only]|
|Minimum supported server||Windows 2000 Server [desktop apps only]|
|Header||winsock.h (include Winsock2.h)|