How to ensure c# finishes writing a file when program is stopped?

Question

I have a c# console app that frequently and quickly writes maybe 1-2mb worth of data to a file (keeps overwriting same file). I then run the program in an infinite loop like this

@echo off
:while
(
   C:\sync.exe
   goto :while
)

and then the c# writes text like this

    private static async Task WriteFile(string filePath, string text)
    {
        string base_path = AppDomain.CurrentDomain.BaseDirectory;
        string file_path = Path.Combine(base_path, filePath);
        using (StreamWriter outputFile = new StreamWriter(file_path))
        {
            await outputFile.WriteAsync(text);
        }
    }

But what I've noticed is that when I end the program, with ctrl+c, or stop the debugger, while it's in the middle of writing, it stops the writing and leave the file corrupted and with missing data.

Is there a way that I can ensure that if the program is stopped mid-write, it either undoes the change (it overwrites the previous file that was there) leaving the old one back again, or it somehow finishes writing (which will take less than a second)?

Answer 1

Is there a way that I can ensure that if the program is stopped mid-write, it either undoes the change (it overwrites the previous file that was there) leaving the old one back again, or it somehow finishes writing (which will take less than a second)?

Yes... write to a different file. When the write is complete, copy the file using this prototype of the Copymethod, setting the third argument to true.

private static async Task WriteFile(string filePath, string text)
{
    string temp_file = File.GetTempFileName();
    string base_path = AppDomain.CurrentDomain.BaseDirectory;
    using (StreamWriter outputFile = new StreamWriter(temp_file))
    {
        await outputFile.WriteAsync(text);
    }
    string file_path = Path.Combine(base_path, filePath);
    File.Copy(temp_file, file_path, true);
    File.Delete(temp_file);
}