Re: IOCPs again

"Igor Tandetnik" <>
Mon, 20 Aug 2007 08:08:21 -0400
"SD" <> wrote in message

1. What is the purpose of the OVERLAPPED structure in an IOCP? It is
not very clear from MSDN. Do we need 1 such structure for every
read/write operation?

Yes. Basically, OVERLAPPED pointer uniquely identifies a particular
asynchronous I/O operation. You pass it to, say, ReadFile, and get it
back in GetQueuedCompletionStatus.

It is common to maintain additional per-operation state by extending
OVERLAPPED structure with your own fields - like this:

struct OpState {
    OVERLAPPED overlapped;
    int moreState;

// or

struct OpState : public OVERLAPPED {
    int moreState;

2. Also, MSDN says that once a handle(like socket) is associated with
an IOCP, it cannnot be used to do ReadFile/ WriteFile operations. In
that case how do you send/ receive data?

Where do you see that? You must have misunderstood something.
With best wishes,
    Igor Tandetnik

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