C# Thead-Safe collection in Object

Question

This is just example code to illustrate my question.

Assume I have the following class:

enter code here
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.Concurrent;


namespace BoxesA4
{
class Box
{
    public double length { get; set; }
    public double width { get; set; }
    public double height { get; set; }

ConcurrentDictionary<int, string> boxItems = new ConcurrentDictionary<int, string>();


    public Box(double length,double width,double height)
    {
        this.length=length;
        this.width = width;
        this.height = height;

    }

    public double volume()
    {
        return this.length * this.width * this.height;
    }

    public void add(int index,string item)
    {
        boxItems.TryAdd(index, item);

    }



    }
}

Main:

    static void Main(string[] args)
    {
       Box createBox = new Box(10,10,5,5);
       createBox.add(0,"hammer");
       createBox.add(1,"saw");

    }

In my main method I am calling createBox.add(); and passing the necessary arguments. Do I have to worry about thread-safety when it comes to calling my add method? I don't want to make the Box class static . If thread-safety is an issue how would I go about fixing my code?

Answer 1

Assuming the behaviour of ConcurrentDictionary.TryAdd meets your requirements, you're fine. You'd be in an even better position if you made the boxItems field read-only.

It's worth reading the docs in detail when you use the concurrent collections, to see exactly what can happen. For example, you may want AddOrUpdate instead of TryAdd - what you do want to happen if the key already exists in the dictionary?

Answer 2

Thread safety is not an issue in your case . your box.add method is effectively adding to Concurrent dictionary which is thread safe. So you need not worry about thread safety.