.NET FileInfo.LastWriteTime & FileInfo.LastAccessTime are wrong

Question

When I call FileInfo(path).LastAccessTime or FileInfo(path).LastWriteTime on a file that is in the process of being written it returns the time tha

Answer 1

From MSDN:

When first called, FileSystemInfo calls Refresh and returns the cached information on APIs to get attributes and so on. On subsequent calls, you must call Refresh to get the latest copy of the information.

FileSystemInfo.Refresh()

If you're application is the one doing the writing, I think you are going to have to "touch" the file by setting the LastWriteTime property your self between each buffer of data you write. Some psuedocode:

while(bytesWritten < totalBytes)
{
   bytesWritten += br.Write(buffer);
   myFileInfo.LastWriteTime = DateTime.Now;
}

I'm not sure how severely this will affect write performance.