Waiting until a file is available for reading with Win32

Question

I\'m watching a directory by calling ReadDirectoryChangesW synchronously. When a new file is available, I try to access it immediately with CreateFile

Answer 1

I don't think there is a notification for the kind of event you're looking for, but as an improvement, I'd suggest progressive delays. This way you will get fast response times for stuff like a drag/drop and won't hog the CPU with a tight loop if the user keeps the file open for an hour in Excel.

int delay= 10;
while ((hFile = CreateFile (path, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL)) == INVALID_HANDLE_VALUE)
{
    if (GetLastError() == ERROR_SHARING_VIOLATION) {
        Sleep (delay);
        if (delay<5120) // max delay approx 5.Sec
            delay*= 2;
    }
    else
        break; // some other error occurred
}