Overlapped (async) ReadFile/win32

abre ora iskam da naburkam koda tuka da wzema greshkata ot ReadFile sled asynchronen dostup (do DVD za w momenta) problema e che Microsoft sa dali slednia primer:

// set up overlapped structure fields 

gOverLapped.Offset     = 0; 

gOverLapped.OffsetHigh = 0; 

gOverLapped.hEvent     = hEvent; 

 

// attempt an asynchronous read operation 

bResult = ReadFile(hFile, &inBuffer, nBytesToRead, &nBytesRead, 

    &gOverlapped) ; 

 

// if there was a problem, or the async. operation's still pending ... 

if (!bResult) 

{ 

    // deal with the error code 

    switch (dwError = GetLastError()) 

    { 

        case ERROR_HANDLE_EOF: 

        { 

            // we're reached the end of the file 

            // during the call to ReadFile 

 

            // code to handle that 

        } 

 

        case ERROR_IO_PENDING: 

        { 

            // asynchronous i/o is still in progress 

 

            // do something else for a while 

            GoDoSomethingElse() ; 

 

            // check on the results of the asynchronous read 

            bResult = GetOverlappedResult(hFile, &gOverlapped, 

                &nBytesRead, FALSE) ; 

 

            // if there was a problem ... 

            if (!bResult) 

            { 

                // deal with the error code 

                switch (dwError = GetLastError()) 

                { 

                    case ERROR_HANDLE_EOF: 

                    { 

                        // we're reached the end of the file 

                        //during asynchronous operation 

                    } 

 

                    // deal with other error cases 

                } 

            } 

        } // end case 

 

        // deal with other error cases 

 

    } // end switch 

} // end if 

problema e che tova


// do something else for a while
GoDoSomethingElse() ;


ich ne e jasno - wuobshte mnogo nejasno. Ne moga da lockwam prilozhenieto w cikul - ne mi se puska oshte edin thread samo zaradi tazi prostotia - wseki frame (60fps sme) tova se pollwa i mozhe da go provejra - obache kak?

njakoi imal li e opit sus ReadFile (to e sushtoto i pod xbox i pod Win2K - pone taka kazwam Mikronsoft).

tirulirutatuutuu

Kakvo tochno te pritesniava? Ne triabva da pollvash nisto.
ERROR_IO_PENDING oznachava che operaciata ne e svurshila -- sinhronno -- i po princip nishto ne tiabva da pravish v toia case, prosto go ostaviash trhread-a da si vurshi druga rabota. Kogato operaciata svurshi hEventa stava signaled state. Mojesh da pravish WaitForSingleObject(hEvent ...) za da proveriavash. Na tebe mai po skoro ti traibva ReadFileEx kudeto mojesh da podavash i completion routine t.e. callback koito se vika ot sustia thread kogato operaciata svurhsi.

use Io Completion Port ?
or GetOverlappedResult(.... , TRUE) ?