Overlapped I/O 事件通知模型和WSAEventSelect模型在实现上非常相似,主要区别在“Overlapped”,Overlapped模型是让应用程序使用重叠数据结构(WSAOVERLAPPED),一次投递一个或多个Winsock I/O请求。这些提交的请求完成后,应用程序会收到通知。什么意思呢?就是说,如果你想从socket上接收数据,只需要告诉系统,由系统为你接收数据,而你需要做的只是为系统提供一个缓冲区~~~~~
Listen线程和WSAEventSelect模型一模一样,Recv/Send线程则完全不同:
procedure TOverlapThread.Execute;
var
dwTemp : DWORD;
ret : Integer;
Index : DWORD;
begin
......
while ( not Terminated ) do
begin
Index := WSAWaitForMultipleEvents( FLinks.Count, @FLinks.Events[0], FALSE, RECV_TIME_OUT, FALSE );
Dec( Index, WSA_WAIT_EVENT_0 );
if Index > WSA_MAXIMUM_WAIT_EVENTS-1 then //超时或者其他错误
continue;
//创建CPU数*2 + 2个线程
for i:=1 to si.dwNumberOfProcessors*2+2 do
begin
AThread := TRecvSendThread.Create( false );
AThread.CompletPort := FCompletPort;//告诉这个线程,你要去这个IOCP去访问数据
end;
procedure TRecvSendThread.Execute;
var
......
begin
while (not self.Terminated) do
begin
//查询IOCP状态(数据读写操作是否完成)
GetQueuedCompletionStatus( CompletPort, BytesTransd, CompletKey, POVERLAPPED(pPerIoDat), TIME_OUT );