ReadDirectoryChangesW
in [Win32 Kernel]
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From: Rod on 26 May 2006 09:24 Hello. How do I implement the function "ReadDirectoryChangesW" asynchronously? (Reference: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/readdirectorychangesw.asp ) MSDN says there are three ways to do it: (1) GetOverlappedResult (2) GetQueuedCompletionStatus using "CreateIoCompletionPort". (3) Using a completion routine. I don't know how to implement any of them. Below is what I'm doing at the moment --- which isn't much. char *chFile1 = "C:\\TMP1"; DWORD dwBytesReturned = 0; FILE_NOTIFY_INFORMATION fni[1024]; HANDLE hDir; hDir = CreateFile (chFile1, // pointer to the file name FILE_LIST_DIRECTORY, // access mode FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, NULL, // security descriptor OPEN_EXISTING, // how to create FILE_FLAG_BACKUP_SEMANTICS, // file attributes NULL ); if (hDir == INVALID_HANDLE_VALUE) { .... handle error and exit. } while(1) { //Non zero if function succeeds. Sleep(2000); if(!ReadDirectoryChangesW( hDir,&fni[0], (sizeof(FILE_NOTIFY_INFORMATION) * 1024), FALSE, FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_LAST_WRITE, &dwBytesReturned, NULL, NULL )) { .... handle error and exit. break; } else { .... handle returned data. } }//End of while. =================end code snippet========================== If anyone can get me over the line I'd be most grateful. Regards, Rod. __ Rod.
From: Arkady Frenkel on 27 May 2006 02:19 Do it on different thread and use sync object ( Critical section ) to read/write results Arkady "Rod" <Siegen052006(a)end.of.message> wrote in message news:ub0e72hhq8njfhq964kno69on5evdvd5ig(a)4ax.com... > Hello. > > How do I implement the function "ReadDirectoryChangesW" > asynchronously? > > (Reference: > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/readdirectorychangesw.asp > ) > > MSDN says there are three ways to do it: > (1) GetOverlappedResult > (2) GetQueuedCompletionStatus using > "CreateIoCompletionPort". > (3) Using a completion routine. > > I don't know how to implement any of them. > > Below is what I'm doing at the moment --- which isn't much. > > char *chFile1 = "C:\\TMP1"; > DWORD dwBytesReturned = 0; > FILE_NOTIFY_INFORMATION fni[1024]; > HANDLE hDir; > > hDir = CreateFile (chFile1, // pointer to the file name > FILE_LIST_DIRECTORY, // access mode > FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, > NULL, // security descriptor > OPEN_EXISTING, // how to create > FILE_FLAG_BACKUP_SEMANTICS, // file attributes > NULL > ); > > if (hDir == INVALID_HANDLE_VALUE) > { > .... handle error and exit. > } > > > while(1) > { //Non zero if function succeeds. > Sleep(2000); > if(!ReadDirectoryChangesW( hDir,&fni[0], > (sizeof(FILE_NOTIFY_INFORMATION) * 1024), > FALSE, FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_LAST_WRITE, > &dwBytesReturned, NULL, NULL )) > { > .... handle error and exit. > break; > } > else > { > .... handle returned data. > } > }//End of while. > > =================end code snippet========================== > > If anyone can get me over the line I'd be most grateful. > > Regards, > > Rod. > > > __ Rod.
From: Rod on 27 May 2006 02:25 On Sat, 27 May 2006 08:19:10 +0200 "Arkady Frenkel" <arkadyf(a)hotmailxdotx.com> wrote: Hello arkady. I know to do it in a separate thread. What I don't understand is how to use either an "overlapped" result, "completion port" or "completion routine" in the context of this API call. I know what they mean I don't know how to implement them. Also, sample code, some of which I can get to, at least, run, is sprinkled with TCHAR. I've never had a need for this type before so I don't understand its relevance to this code and I am uncertain of how to convert a TCHAR back into a "normal" data type. A few lines of explained example code should be enough to get me on my way again, if you or someone else could provide some. THanks for responding. Regards, Rod. :> Do it on different thread and use sync object ( Critical section ) to :> read/write results :> Arkady :> :> "Rod" <Siegen052006(a)end.of.message> wrote in message :> news:ub0e72hhq8njfhq964kno69on5evdvd5ig(a)4ax.com... :> > Hello. :> > :> > How do I implement the function "ReadDirectoryChangesW" :> > asynchronously? :> > :> > (Reference: :> > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/readdirectorychangesw.asp :> > ) :> > :> > MSDN says there are three ways to do it: :> > (1) GetOverlappedResult :> > (2) GetQueuedCompletionStatus using :> > "CreateIoCompletionPort". :> > (3) Using a completion routine. :> > :> > I don't know how to implement any of them. :> > :> > Below is what I'm doing at the moment --- which isn't much. :> > :> > char *chFile1 = "C:\\TMP1"; :> > DWORD dwBytesReturned = 0; :> > FILE_NOTIFY_INFORMATION fni[1024]; :> > HANDLE hDir; :> > :> > hDir = CreateFile (chFile1, // pointer to the file name :> > FILE_LIST_DIRECTORY, // access mode :> > FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, :> > NULL, // security descriptor :> > OPEN_EXISTING, // how to create :> > FILE_FLAG_BACKUP_SEMANTICS, // file attributes :> > NULL :> > ); :> > :> > if (hDir == INVALID_HANDLE_VALUE) :> > { :> > .... handle error and exit. :> > } :> > :> > :> > while(1) :> > { //Non zero if function succeeds. :> > Sleep(2000); :> > if(!ReadDirectoryChangesW( hDir,&fni[0], :> > (sizeof(FILE_NOTIFY_INFORMATION) * 1024), :> > FALSE, FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_LAST_WRITE, :> > &dwBytesReturned, NULL, NULL )) :> > { :> > .... handle error and exit. :> > break; :> > } :> > else :> > { :> > .... handle returned data. :> > } :> > }//End of while. :> > :> > =================end code snippet========================== :> > :> > If anyone can get me over the line I'd be most grateful. :> > :> > Regards, :> > :> > Rod. :> > :> > :> > __ Rod. :> __ Rod.
From: Arkady Frenkel on 27 May 2006 06:56 Hi, Rod! But you haven't IO operations in the contect you shown so IMHO you don't need either overlapped nor IOCP there Overlapped alow you to ask read/write to/from different buffers and IOCP used be server to serve multiple clients in scalable way. Do you have those demands in your code? Arkady "Rod" <Siegen032005(a)end.of.message> wrote in message news:4prf72pkemuocd5bucua493207fm12d9qe(a)4ax.com... > On Sat, 27 May 2006 08:19:10 +0200 "Arkady Frenkel" > <arkadyf(a)hotmailxdotx.com> wrote: > > Hello arkady. > > I know to do it in a separate thread. What I don't > understand is how to use either an "overlapped" result, > "completion port" or "completion routine" in the context of > this API call. I know what they mean I don't know how to > implement them. > > Also, sample code, some of which I can get to, at least, > run, is sprinkled with TCHAR. I've never had a need for this > type before so I don't understand its relevance to this code > and I am uncertain of how to convert a TCHAR back into a > "normal" data type. > > A few lines of explained example code should be enough to > get me on my way again, if you or someone else could provide > some. > > THanks for responding. > > Regards, > > Rod. > > :> Do it on different thread and use sync object ( Critical section ) to > :> read/write results > :> Arkady > :> > :> "Rod" <Siegen052006(a)end.of.message> wrote in message > :> news:ub0e72hhq8njfhq964kno69on5evdvd5ig(a)4ax.com... > :> > Hello. > :> > > :> > How do I implement the function "ReadDirectoryChangesW" > :> > asynchronously? > :> > > :> > (Reference: > :> > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/readdirectorychangesw.asp > :> > ) > :> > > :> > MSDN says there are three ways to do it: > :> > (1) GetOverlappedResult > :> > (2) GetQueuedCompletionStatus using > :> > "CreateIoCompletionPort". > :> > (3) Using a completion routine. > :> > > :> > I don't know how to implement any of them. > :> > > :> > Below is what I'm doing at the moment --- which isn't much. > :> > > :> > char *chFile1 = "C:\\TMP1"; > :> > DWORD dwBytesReturned = 0; > :> > FILE_NOTIFY_INFORMATION fni[1024]; > :> > HANDLE hDir; > :> > > :> > hDir = CreateFile (chFile1, // pointer to the file name > :> > FILE_LIST_DIRECTORY, // access mode > :> > FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, > :> > NULL, // security > descriptor > :> > OPEN_EXISTING, // how to create > :> > FILE_FLAG_BACKUP_SEMANTICS, // file attributes > :> > NULL > :> > ); > :> > > :> > if (hDir == INVALID_HANDLE_VALUE) > :> > { > :> > .... handle error and exit. > :> > } > :> > > :> > > :> > while(1) > :> > { //Non zero if function succeeds. > :> > Sleep(2000); > :> > if(!ReadDirectoryChangesW( hDir,&fni[0], > :> > (sizeof(FILE_NOTIFY_INFORMATION) * 1024), > :> > FALSE, FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_LAST_WRITE, > :> > &dwBytesReturned, NULL, NULL )) > :> > { > :> > .... handle error and exit. > :> > break; > :> > } > :> > else > :> > { > :> > .... handle returned data. > :> > } > :> > }//End of while. > :> > > :> > =================end code snippet========================== > :> > > :> > If anyone can get me over the line I'd be most grateful. > :> > > :> > Regards, > :> > > :> > Rod. > :> > > :> > > :> > __ Rod. > :> > > __ Rod.
From: Tim Roberts on 28 May 2006 00:44
Rod <Siegen032005(a)end.of.message> wrote: > >I know to do it in a separate thread. What I don't >understand is how to use either an "overlapped" result, If you use a separate thread, it is not NECESSARY to use a second thread. Just let the call block. That's the beauty of using another thread. On the other hand, using an overlapped result is not hard. Create an OVERLAPPED structure on the stack. Create an event using CreateEvent, and shove its handle into the hEvent. Pass the structure to ReadDirectoryChangesW. The function will return immediately. Now you can go do something else, and when you run out of things to do, call WaitForSingleEvent on the event in the overlap structure. When it finally finishes, use GetOverlappedResult to get the results. Be sure to open the directory with FILE_FLAG_OVERLAPPED. -- - Tim Roberts, timr(a)probo.com Providenza & Boekelheide, Inc. |