using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Text;

 using System.Threading.Tasks;

 using System.Threading;

 using System.Collections.Concurrent;

 namespace CSharpStudy.ParallelStudy

 {

     class HowToReturnList

     {

         public static void Error_Test()

         {

             var list = Enumerable.Range(, );

             var results = new List<string>();

             Parallel.ForEach(list, (item) =>

             {

                 results.Add("item:" + item);

             });

             Console.WriteLine(results.Count);

         }

         public static void Lock_Test()

         {

             var list = Enumerable.Range(, );

             var results = new List<string>();

             Parallel.ForEach(list, (item) =>

             {

                 lock (results)

                 {

                     results.Add("item:" + item);

                 }

             });

             Console.WriteLine(results.Count);

         }

         public static void Concurrent_Collections_Test()

         {

             var list = Enumerable.Range(, );

             var results = new ConcurrentQueue<string>();

             Parallel.ForEach(list, (item) =>

             {

                 lock (results)

                 {

                     results.Enqueue("item:" + item);

                 }

             });

             Console.WriteLine(results.Count);

         }

         public static void Task_Test()

         {

             var list = Enumerable.Range(, );

             var tasks = list.Select(item =>

             {

                 return Task.Run<string>(() =>

                 {

                     return "item:" + item;

                 });

             }).ToArray();

             Task.WhenAll(tasks);

             Console.WriteLine(tasks.Select(x => x.Result).Count());

         }

         public static void PLinq_Test()

         {

             var list = Enumerable.Range(, );

             var results = list.AsParallel().Select(item => "item:" + item);

             Console.WriteLine(results.Count());

         }

     }

 }