Thread Safety .Net C#: thread safety, static constructors, .net

Thread Safety .Net C#

Just for the sake of my own edification...I'd appreciate your thoughts.

is the following thread-safe?

public class MyClass
{
	private static readonly int _intValue = 123;
	private static readonly string _stringValue = "one two three";
 
	static MyClass() // Empty static constructor
	{
	}
 
	public MyClass()
	{
                     // instance init
	}
 
	public int IntValue
	{
		get { return _intValue; }
	}
 
	public string StringValue
	{
		get { return _stringValue; }
	}
}

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It's not always as simple as it looks. For the integer that is specified in the code I go along with what's already said: it is readonly and that's that.

For the string value, it's quite right as long as you behave...

For any reference type: this simply will not hold.

In the code below I added a reference type: IList<String>, which is just as mutable as any other reference type, it can only not be assigned to. Thread safe: not in the least.

Just for the exercise, i added some code in the constructor that changes the first letter of our "immutable" string. Thread safe: only if you are nice. Note that even the integer can be changed in that way by setting the private field m_value....

Bottom line is: when you behave and you are the only one to play with your code, and we are not talking reference types, this is quite ok. Strings are quite close to being reference types but Microsoft went a long way to make us believe otherwise. If you create a library that is said to be thread safe and you are going to sell it: make sure you add these thread-safe interlocking mechanisms or some day you will be fried...

Use the code below and do:

MyClass mc = new MyClass();
// s holds now "Xne two three"
string s = mc.StringValue;

-- Abel --

    public class MyClass
    {
        private static readonly int _intValue = 123;
        private static readonly string _stringValue = "one two three";
        private static IList<String> _states = new List<String>();
 
        static MyClass() // Empty static constructor
        {
        }
 
        public MyClass()
        {
            // very modifiable
            _states.Add("Arkansas");
            // modifiable
            Type stringType = _stringValue.GetType();
            stringType.InvokeMember("SetChar",
                BindingFlags.InvokeMethod |
                BindingFlags.Instance |
                BindingFlags.NonPublic,
                null, _stringValue, new object[] {0, 'X'});
        }
 
        
        public int IntValue
        {
            get { return MyClass._intValue; }
        }
 
        public string StringValue
        {
            get { return _stringValue; }
        }

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Thread Safety .Net C#

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thread safety

static constructors

.net

C# Programming Language

Microsoft Visual C#.Net

.NET

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