C #: asynchronous file reading (encoding)

Good day.

In order to educate myself, I set myself the task: - there is a text file in which the Windows service writes text lines to this file, so I decided to write an application that reads data from that file synchronously so that it does not block for the service.

Code:

private async void btnOpenFile_Click(object sender, EventArgs e) { OpenFileDialog dialog = new OpenFileDialog(); dialog.InitialDirectory = "C:\\"; dialog.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"; dialog.FilterIndex = 2; dialog.RestoreDirectory = true; if (dialog.ShowDialog() == DialogResult.OK) { _fileName = tbFileName.Text = dialog.FileName; try { rtbText.Text = await GetFileText(); } catch (Exception ex) { MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message); } } } async Task<string> GetFileText() { using (FileStream sourceStream = new FileStream(_fileName, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize: 4096, useAsync: true)) { StringBuilder sb = new StringBuilder(); byte[] buffer = new byte[0x1000]; int numRead; while ((numRead = await sourceStream.ReadAsync(buffer, 0, buffer.Length)) != 0) { //string text = Encoding.ASCII.GetString(buffer, 0, numRead); string text = Encoding.GetEncoding(1251).GetString(buffer, 0, numRead); sb.Append(text); } MessageBox.Show("Loading complete..."); return sb.ToString(); } } 

I encountered the following problems:

1. When the service writes to the file, an error occurs (the file is occupied by another process)
2. How to determine the file encoding of the read file?
3. How to find out the size of the buffer (new byte [0x1000]), which I need for a specific file? After all, the file is constantly increasing in size

Please share your thoughts on this.

Thank.