ConcurrentDictionary

Introduction:

In a previous post I'd talked about the Dictionary type.  Ever wonder if there's a thread-safe version out there to use?  ConcurrentDictionary is what you seek.  Introduced in .net 4.0, we still get the same key/value pairing available before.  But enough about definitions, lets do some coding.

Coding:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.Concurrent;

namespace DictionarySample
{
  class Program
  {
    static void Main(string[] args)
    {
      //step 1: create!
      ConcurrentDictionary<string, string> theRain = new ConcurrentDictionary<string, string>();
      theRain.GetOrAdd("Daniel", "c0d3r");
      theRain.GetOrAdd("Bob", "$ql script kiddi3");
      theRain.GetOrAdd("Dan", "c0d3r");
      theRain.GetOrAdd("Peter", "t@$k m@$t3r");
      
      //step 2: test
      Console.WriteLine("Testing time of our ConcurrentDictionary");
      Console.WriteLine("does myDic.ContainsKey(chode)? : " + theRain.ContainsKey("chode").ToString() + " ");
      Console.WriteLine("does myDic.ContainsKey(Peter)? : " + theRain.ContainsKey("Peter").ToString() + " ");
      Console.WriteLine("does myDic.ContainsKey(peter)? : " + theRain.ContainsKey("peter").ToString() + " ");
      Console.WriteLine();
      // step 3: write out data
      Console.WriteLine("initial data value(s) loaded in our ConcurrentDictionary");
      foreach (var pair in theRain)
        Console.WriteLine(pair.Key + " " + pair.Value);

      // step 4: update some data.
      theRain.TryUpdate("Peter", "koala", "Uber");
      Console.WriteLine();
      Console.WriteLine("value of Peter : " + theRain["Peter"]);
      Console.WriteLine();

      theRain.TryUpdate("Peter", "koala", "t@$k m@$t3r");
      Console.WriteLine();
      Console.WriteLine("value of Peter : " + theRain["Peter"]);
      Console.WriteLine();

      //step 5: write out the data
      Console.WriteLine("Modified data value(s) loaded in our ConcurrentDictionary");
      foreach (var pair in theRain)
        Console.WriteLine(pair.Key + " " + pair.Value);
      Console.WriteLine("\nPress Any Key to Exit.");
      Console.ReadKey();
    }
  }
}

Step 1: The constructor part is easy enough, create it quite similarly like we did with the Dictionary blog.
Step 2: doing some QA to see if ConcurrentDictionary really does act like the regular Dictionary.  It does!
Step 3: displaying the data to verify what was originally created exists as we expect.
Step 4: Attempting to update some data, for my sample I'm going to turn the key Peter into the value of koala instead of t@$k m@$t3r.  As the value of Peter isn't Uber it won't update.  As the value of Peter is t@$k m@$t3r it will update and now Peter is a koala.
Step 5: displaying out the data to verify what we've modified exists as we expect.

and the output:

Source:

Microsoft ConcurrentDictionary