Return Values
If the function dequeues a completion packet for a successful I/O operation from the completion port, the return value is nonzero. The function stores information in the variables pointed to by the lpNumberOfBytesTransferred, lpCompletionKey, and lpOverlapped parameters.
如果函数从完成端口的一个成功I/O操作取出一个完成包，返回值为非0。函数在指向lpNumberOfBytesTransferred, lpCompletionKey, and lpOverlapped的参数指针中存储相关信息。
If *lpOverlapped is NULL and the function does not dequeue a completion packet from the completion port, the return value is zero. The function does not store information in the variables pointed to by the lpNumberOfBytes and lpCompletionKey parameters. To get extended error information, call GetLastError. If the function did not dequeue a completion packet because the wait timed out, GetLastError returns WAIT_TIMEOUT.
如果 *lpOverlapped为空并且函数没有从完成端口得到完成包，返回值为0，函数则不会再lpNumberOfBytes and lpCompletionKey所指向的参数中存储信息。调用GetLastError可以得到一个扩展信息。如果函数因为等待超时未能得到完成包，GetLastError返回WAIT_TIMEOUT.
If *lpOverlapped is not NULL and the function dequeues a completion packet for a failed I/O operation from the completion port, the return value is zero. The function stores information in the variables pointed to by lpNumberOfBytes, lpCompletionKey, and lpOverlapped. To get extended error information, call GetLastError.
如果 *lpOverlapped不为空并且函数从完成端口的一个失败I/O操作得到完成包，返回值为0，函数在指向lpNumberOfBytesTransferred, lpCompletionKey, and lpOverlapped的参数指针中存储相关信息。调用GetLastError可以得到扩展错误信息
If a socket handle associated with a completion port is closed, GetQueuedCompletionStatus returns ERROR_SUCCESS, with lpNumberOfBytes equal zero.
如果一个socket句柄关联到一个完成端口被关闭了，则GetQueuedCompletionStatus返回ERROR_SUCCESS,并且lpNumberOfBytes等于0
