c# - How to execute a block of code only once on a multithreading environment?

Question

The following code block, performs loading of an object in C#.

public bool IsModelLoaded { get; set; }
public override MyObject Load()
{
    if (!IsModelLoaded)
    {
        Model = MyService.LoadMyObject(Model);
        IsModelLoaded = true;
    }
    return Model;
}

My intention is to run this block only once, and hence loading the Model only once. Nevertheless, this code block runs twice from 2 different threads.

How can I make sure that this block runs only once? (on multiple threads).

Answer 1

Use the Lazy<T> Class:

private readonly Lazy<MyObject> myObject;

public MyClass()
{
    myObject = new Lazy<MyObject>(() =>
    {
        return MyService.LoadMyObject();
    }, LazyThreadSafetyMode.ExecutionAndPublication);
}

public bool IsModelLoaded
{
    get { return myObject.IsValueCreated; }
}

public override MyObject Load()
{
    return myObject.Value;
}