GetQueuedCompletionStatus的返回值

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队列中取得一个IO操作成功的完成包，那么返回值不等于0。 在lpNumberOfBytesTransferred, lpCompletionKey, and lpOverlapped这些参数所指向的变量中存储了这个完成包的相关信息。  
 
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NULL， 且函数没能从完成端口取出一个完成包，返回值则为0。函数则不会在lpNumberOfBytes and lpCompletionKey所指向的参数中存储信息。调用GetLastError， 可以得到一个扩展错误信息。如果因为等待超时而未能出列一个完成包，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， 且函数从完成端口出列一个失败的I/O操作的完成包，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.  
 
如果与完成端口相关联的一个套接字句柄被关闭，GetQueuedCompletionStatus返回ERROR_SUCCESS， 且lpNumberOfBytes等于0
 
Remarks(注意)
This function associates a thread with the specified completion port. A thread can be associated with at most one completion port.
 
这个函数分配一个线程给指定的完成端口，一个线程最多只能与一个完成端口相关联（一个线程只能为一个完成端口提供服务）
 
The I/O system can be instructed to send completion notification packets to completion ports, where they are queued. The CreateIoCompletionPort function provides a mechanism for this.
 
I/O系统能够发送完成通知到完成端口，并使之队列有序，CreateIoCompletionPort函数提供了这样的机制
 
When you perform an input/output operation with a file handle that has an associated input/output completion port, the I/O system sends a completion notification packet to the completion port when the I/O operation comple tes. The completion port places the completion packet in a first-in-first-out queue. The GetQueuedCompletionStatus function retrieves these queued completion packets.
 
当你在一个文件句柄上执行一个输入输出操作，这个文件句柄有一个相关联的完成端口，I/O操作完成的时候，I/O系统发送一个完成通知到完成端口。完成端口把这个完成通知追加到一个先进先出的队列中。GetQueuedCompletionStatus 函数可以按照正确的顺序得到这些完成包
 
A server application may have several threads calling GetQueuedCompletionStatus for the same completion port. As input operations complete, the operating system queues completion packets to the completion port. If threads are actively waiting in a call to this function, queued requests complete their call. For more information, see I/O Completion Ports.
 
一个服务器应用程序，可以有多个线程在同一个完成端口上同时调用GetQueuedCompletionStatus。输入操作完成，操作系统把排好队的完成包交给完成端口。如果线程正在等待这个函数返回，则被激发。他们的调用请求也会被排队完成。更多信息请查看 I/O Completion Ports.
 
You can call the PostQueuedCompletionStatus function to post an completion packet to an completion port. The completion packet will satisfy an outstanding call to the GetQueuedCompletionStatus function.
 
你能调用PostQueuedCompletionStatus函数投递一个完成包到一个完成端口，完成包将确保GetQueuedCompletionStatus 调用返回。