Devbotas-Software-Settings

For many years, we've been using File.WriteAllText and File.ReadAllText methods to store program settings in file. However, every once in a while, when debugging client's broken systems, we find settings file completely empty. It is a complete mystery of why this happens, but it happens nevertheless and thus we decided to build a reliable multi-stage write process that at least guarantees us a valid settings file. Sure, if the power is cut during the write, newest changes will be lost, but then at least original file will be restored automatically.

ReliableFile

Let's take settings.txt file as an example. To read its content, use either of these methods:

public bool TryReadAllText(out string fileContent) 
public bool TryReadAllBytes(out byte[] fileContent) 

Since read operations are inherently quite safe, not much is happening behind the scenes. It is just a silent wrapper around File.ReadAllBytes which does not throw any exceptions.

The story is different for write counterparts:

public bool TryWriteAllBytes(byte[] bytesToWrite)
public bool TryWriteAllText(string textToWrite)

When calling those it goes like this:

1. New content is written to settings.txt.rf1
2. settings.txt.rf1 is renamed to settings.txt.rf2
3. settings.txt is deleted
4. settings.txt.rf2 is renamed to settings.txt

Each step, starting from #2, validates the previous one; so, if the application crashed during file write, there are quite a few good oppurtinities to restore the file - at least to the original content. This is done automatically when calling Initialize method.

Here's a basic usage example:

var reliableFile = new ReliableFile();
reliableFile.Initialize("temp/someFile.txt");
if (reliableFile.TryReadAllText(out var fileContent)){
    Debug.Write(fileContent);
};

SettingsProvider

This class provides dictionary-like settings storage and utilizes ReliableFile. It is simplistic by design. It only allows storing very simple data types: float, string and bool. Also, there are no sections or categories. It is meant to store a handful of settings, and do that reliably.

Content is saved as JSON.

Here's how to use it:

// Preparing an underlying ReliableFile.
var settingsFile = new ReliableFile();
settings.Initialize(settingsFile);

// Loading that file into SettingsProvider.
var settings = new SettingsProvider();
settingsFile.Initialize("temp/someSettings.json");

// Setting and getting a value.
settings.TrySet("SomeNumberKey", 123);
settings.TryGet("SomeNumberKey", out float someIntegerValue);

// When getting a non-existent setting, you may also specify a default value.
var setting = settings.Get("SomeNonExistentKey", "Default value");