들어가며

참고

• https://github.com/quozd/awesome-dotnet

Thread & Task

coroutine

https://docs.unity3d.com/Manual/Coroutines.html

StartCoroutine https://github.com/Unity-Technologies/UnityCsReference/blob/e740821767d2290238ea7954457333f06e952bad/Runtime/Export/Scripting/MonoBehaviour.bindings.cs#L81

Task.Factory.StartNew(action)
	Task.Factory.StartNew(action, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Current);

Task.Run(action)
	Task.Factory.StartNew(action, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);


TaskCreationOptions.None            TaskScheduler.Current
TaskCreationOptions.DenyChildAttach TaskScheduler.Default

Task

• TPL (Task Parallel Library)

• https://docs.microsoft.com/en-us/dotnet/standard/parallel-programming/task-parallel-library-tpl

• Task-based asynchronous programming

• https://docs.microsoft.com/en-us/dotnet/standard/parallel-programming/task-based-asynchronous-programming

  • Task.Run
  • Task.Factory.StartNew

• ValueTask

  • https://stackoverflow.com/questions/43000520/why-would-one-use-taskt-over-valuetaskt-in-c
  • https://devblogs.microsoft.com/dotnet/understanding-the-whys-whats-and-whens-of-valuetask/

• Dissecting the async methods in C#

  • https://devblogs.microsoft.com/premier-developer/dissecting-the-async-methods-in-c/

• Unwrap()의 목적:

  • How to: Unwrap a Nested Task
  • Task<Task>를 Task로 변환함.
  • 중첩된 Task 구조를 단일 Task로 평탄화함

TaskScheduler

• https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskscheduler?view=net-6.0

SynchronizationContext

• C# SynchronizationContext 와 await

  • SynchronizationContext에 현재 쓰레드 정보를 저장해 놨다 다른 쓰레드에서 상호작용에서 필요시 꺼내 쓴다.
  • https://korsa.tistory.com/94

• https://docs.microsoft.com/en-us/dotnet/api/system.threading.synchronizationcontext?view=net-6.0

  • UnitySynchronizationContext
  • UniTaskSynchronizationContext

• Parallel Computing - It's All About the SynchronizationContext

The idea behind ISynchronizeInvoke is that a “source” thread can queue a delegate to a “target” thread, optionally waiting for that delegate to complete. ASP.NET asynchronous pages aren’t associated with a single thread. Instead of queuing work to the original thread, asynchronous pages only need to maintain a count of outstanding operations to determine when the page request can be completed. After much thought and careful design, ISynchronizeInvoke was replaced by SynchronizationContext.

provides a way to queue a unit of work to a context. - SynchronizationContext does not include a mechanism to determine if synchronization is necessary, because this isn’t always possible. every thread has a “current” context. it keeps a count of outstanding asynchronous operations

ConfigureAwait provides a means to avoid the default SynchronizationContext capturing behavior; passing false for the flowContext parameter prevents the SynchronizationContext from being used to resume execution after the await. There’s also an extension method on SynchronizationContext instances called SwitchTo; this allows any async method to change to a different SynchronizationContext by invoking SwitchTo and awaiting the result.

ConfigureAwait

• https://devblogs.microsoft.com/dotnet/configureawait-faq/

• https://www.sysnet.pe.kr/2/0/11418

• 기본값은 ConfigureAwait(continueOnCapturedContext: true)입니다

  • true: await가 완료되도 SynchronizationContext 유지
  • false: await가 완료되도 SynchronizationContext 유지하지 않음.

• https://blog.stephencleary.com/2012/07/dont-block-on-async-code.html

• https://docs.microsoft.com/en-us/archive/msdn-magazine/2013/march/async-await-best-practices-in-asynchronous-programming?WT.mc_id=DT-MVP-4038148

async stream

• https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-8.0/async-streams

• https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/tutorials/generate-consume-asynchronous-stream

• https://dev.to/noseratio/asynchronous-coroutines-with-c-8-0-and-iasyncenumerable-2e04

• https://stackoverflow.com/a/55085418 the thread pool task scheduler and a synchronization context task scheduler

• https://github.com/dotnet/runtime/blob/c3fa7655ea3006f010780d325addcd04aaffa76b/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/TaskScheduler.cs#L297

• https://github.com/dotnet/runtime/blob/c3fa7655ea3006f010780d325addcd04aaffa76b/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ThreadPoolTaskScheduler.cs#L21

TAP

Task-based Asynchronous Pattern

TaskFactory Task Unwrap, ContinueWith

generated: IAsyncStateMachine AsyncMethodBuilder CancellationToken

Task

• Unwrap
  • Creates a proxy Task

public static System.Threading.Tasks.Task Unwrap (this System.Threading.Tasks.Task<System.Threading.Tasks.Task> task);
Task<Task<int>> barMarker = Bar();
Task<int> awaitedMarker = await barMarker;
Task<int> unwrappedMarker = barMarker.Unwrap();

• ContinueWith

  • Creates a continuation that executes asynchronously when the target Task completes.

• Task.Run하고 Task.Factory.StartNew

  • Task.Run (someAction);
    • Task.InternalStartNew
  • Task.Factory.StartNew(someAction, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);
    • Task.InternalStartNew

TaskCreationOptions.DenyChildAttach

public Task StartNew(Action action)
{
    Task? currTask = Task.InternalCurrent;
    return Task.InternalStartNew(
        currTask,
        action,
        null,
        m_defaultCancellationToken,
        GetDefaultScheduler(currTask),
        m_defaultCreationOptions,
        InternalTaskOptions.None);
}

internal static Task InternalStartNew(
        Task? creatingTask,
        Delegate action
        object? state,
        CancellationToken cancellationToken,
        TaskScheduler scheduler,
        TaskCreationOptions options,
        InternalTaskOptions internalOptions)

CancellationTokenSource & CancellationToken

• CancellationTokenSource : IDisposable

  • Cancel()을 호출하여 취소 신호를 보내는 역할
    • Cancel을 여러 번 호출이 안전하며, 상태가 변경되지 않은 상태로 남아 있음.
  • Dispose전 Cancel도 해주자
  • CancellationTokenSource.Token => CancellationToken

• CancellationToken:

  • 실제로 취소가 발생했는지를 감지할 수 있는 수동적인 토큰.
  • 콜백이 이미 실행 중이거나 완료된 경우 다시 실행되지 않음.
  • IsCancellationRequested: 현재 취소 요청 여부를 확인할 수 있음.
  • ThrowIfCancellationRequested: OperationCanceledException 예외 발생

• https://learn.microsoft.com/ko-kr/dotnet/api/system.threading.cancellationtoken?view=net-9.0

// 토큰은 합칠 수 도 있다.
CancellationToken combinedToken = CancellationTokenSource.CreateLinkedTokenSource(token1, token2).Token;

SynchronizationContext

• SynchronizationContext
  • thread동기화할때 사용하면 좋다

public static System.Threading.SynchronizationContext? Current { get; }

• ex
  • WPF - DispatcherSynchronizationContext
  • MAUI - DispatcherQueueSynchronizationContext
  • ASP.NET AspNetSynchronizationContext

Thread thread = Thread.CurrentThread;
int threadId = thread.ManagedThreadId;
int threadId = Thread.CurrentThread.ManagedThreadId;
int processorId = Thread.GetCurrentProcessorId();

SynchronizationContext context = SynchronizationContext.Current;

TaskScheduler

• TaskScheduler.FromCurrentSynchronizationContext
  • UI쓰레드등. task 동기화할때 사용하면 좋다
  • 메인쓰레드(유니티)

TaskScheduler scheduler = TaskScheduler.FromCurrentSynchronizationContext();
TaskScheduler scheduler2 = TaskScheduler.Current;

namespace System.Threading.Tasks
{
    public abstract class TaskScheduler
    {
      public static TaskScheduler Current => InternalCurrent ?? Default;
      internal static TaskScheduler? InternalCurrent
      {
          get
          {
              Task? currentTask = Task.InternalCurrent;
          }
      }
      public static TaskScheduler FromCurrentSynchronizationContext()
      {
          return new SynchronizationContextTaskScheduler();
      }
    }
}

class Program
{
    static void Main()
    {
        ProcessThread thread = GetCurrentThread();
        Console.WriteLine($"현재 스레드의 ID: {thread.Id}");
        Console.WriteLine($"현재 스레드가 동작하는 코어: {GetProcessorAffinity(thread)}");
    }

    static ProcessThread GetCurrentThread()
    {
        int threadId = Thread.CurrentThread.ManagedThreadId;
        Process currentProcess = Process.GetCurrentProcess();
        return currentProcess.Threads.Cast<ProcessThread>().FirstOrDefault(t => t.Id == threadId);
    }

    static int GetProcessorAffinity(ProcessThread thread)
    {
        return (int)thread.ProcessorAffinity;
    }
}

ConfigureAwait

• https://devblogs.microsoft.com/dotnet/configureawait-faq/

// System.Runtime.CompilerServices

public ConfiguredTaskAwaitable ConfigureAwait (bool continueOnCapturedContext);

Awaiter

public TaskAwaiter<bool> GetAwaiter()
{
    return _downloadAllTask.GetAwaiter();
}

public bool IsCompleted
{
    get
    {
    }
}

public void GetResult() { }

INotifyCompletion, ICriticalNotifyCompletion

// INotifyCompletion
void OnCompleted(Action continuation)
{
}

// ICriticalNotifyCompletion : System.Runtime.CompilerServices.INotifyCompletion

public void OnCompleted (Action continuation)
{
}
public void UnsafeOnCompleted (Action continuation)
{
}

ValueTask

public async Task<bool> MoveNextAsync()
{
    if (_bufferdCount == 0)
    {
        await FillBuffer();    // 새로운 Task<bool> 객체를 할당
    }
    return _bufferedCount > 0; // (true와 false), 오직 2개의 Task<bool> 객체만 필요.
}

private readonly Dictionary<int, string> _cache = new Dictionary<int, string>();
public async ValueTask<string> GetCachedDataAsync(int id)
{
    if (_cache.TryGetValue(id, out string cachedData))
    {
        // 동기적으로 바로 반환 가능할 때, ValueTask가 메모리 할당을 줄여줌
        return cachedData;
    }

    // 없으면, 비동기 작업으로 데이터를 가져옴
    string data = await FetchDataFromDatabaseAsync(id);
    _cache[id] = data;
    return data;
}

private async Task<string> FetchDataFromDatabaseAsync(int id)
{
    await Task.Delay(100); // 데이터베이스에서 가져온다고 가정
    return $"Data_{id}";
}

• Task는 Class.
  • Task같은경우 경우의 수가 많기에, 보다 적은수의 캐싱을 유지
  • 완료될 때까지 대기할 수 있으며, 실행이 완료되면 IsCompleted, Result, GetAwaiter().GetResult()와 같은 API가 작업을 완료 상태로 유지.
  • 여러 스레드에서 안전하게 접근할 수 있도록 설계됨.
• ValueTask는 Struct
  • 캐싱 걱정 없음
  • 기본적으로 싱글 컨슈머(single-consumer) 패턴을 전제로 하여 가볍게 설계됨.
  • ValueTask는 IValueTaskSource라는 인터페이스를 사용해 동작할 수 있으며, 메모리 할당을 최소화하는 방식으로 작동.
    • 이로 인해 ValueTask는 여러 스레드에서 동시에 접근하거나 두 번 이상 await하는 경우 문제가 발생할 수 있다.

• 메모리 효율성: 데이터가 캐시에 있을 경우, 동기적으로 완료되므로 Task 객체를 생성하지 않아 메모리 할당이 줄어듬.
• 메모리 할당 감소 효과: ValueTask는 주로 결과가 이미 완료된 작업이나 반복적인, 짧은 작업에서 메모리 할당을 줄이기 위해 사용됨.
• 복잡한 에러 처리 및 호출 방식: ValueTask를 사용할 때는 한 번만 await 가능하거나 단일 소비자 패턴을 따라야 하는 제약 사항이 있는데, 이 경우 ComputeFromStreamAsync를 호출할 코드가 많아질 수 있음. Task는 안전하게 여러 번 await할 수 있어 더 관리가 용이함.
• 동기 완료 가능성: ValueTask는 동기적으로 완료될 가능성이 높은 경우에 적합함. 이 메서드는 비동기적으로 스트림을 읽는 작업이므로 동기 완료 가능성이 거의 없어, ValueTask가 적절하지 않음.

Parallel

• Task task = Task.Run(() => Parallel.ForEach(
• await Parallel.ForEachAsync
  • System.Threading.Tasks.Parallel.dll

TLS

[ThreadStatic] 

ThreadLocal<T>

AsyncLocal<T>

ExecutionContext.SuppressFlow()

Ref

• https://learn.microsoft.com/en-us/dotnet/standard/asynchronous-programming-patterns/task-based-asynchronous-pattern-tap
• https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-10.0/async-method-builders
  • C#10
• https://devblogs.microsoft.com/pfxteam/task-run-vs-task-factory-startnew/
• https://www.sysnet.pe.kr/2/0/11417
• https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskcreationoptions?view=net-7.0
• Nested Tasks and Child Tasks
  • https://learn.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/dd997417(v=vs.100)
• UnityMainThreadDispatcher
  • https://github.com/PimDeWitte/UnityMainThreadDispatcher
• https://weblogs.asp.net/dixin/understanding-c-sharp-async-await-1-compilation
• https://www.sysnet.pe.kr/2/0/13191

.tt

• TextTransform .exe

  • https://learn.microsoft.com/ko-kr/visualstudio/modeling/generating-files-with-the-texttransform-utility?view=vs-2022
  • \Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE
  • \Program Files\Microsoft Visual Studio\2022\Professional\Common7\IDE
  • \Program Files\Microsoft Visual Studio\2022\Enterprise\Common7\IDE

• T4 Text Template Transformation Toolkit

https://learn.microsoft.com/ko-kr/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2022

package System.CodeDom

T4를 이용한 INotifyPropertyChanged 코드 자동 생성

Liquid https://shopify.github.io/liquid/ https://github.com/lekman/AzureLiquid

<!-- 
Ref: https://learn.microsoft.com/en-us/visualstudio/msbuild/item-element-msbuild?view=vs-2022#attributes

-->

  <ItemGroup>
  
    <None Update="TextTemplate1.tt">
      <Generator>TextTemplatingFileGenerator</Generator>
      <LastGenOutput>TextTemplate1.txt</LastGenOutput>
    </None>
    <None Update="TextTemplate1.txt">
      <DesignTime>True</DesignTime>
      <AutoGen>True</AutoGen>
      <DependentUpon>TextTemplate1.tt</DependentUpon>
    </None>
  </ItemGroup>

  <ItemGroup>
    <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
  </ItemGroup>

<Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />

• Solution Explorer > .tt > 우클릭 > Debug T4 Template
• 혹은

<#@ template debug="true" hostSpecific="true" #>
<#@ import namespace="System.Diagnostics" #>
<# Debugger.Launch(); #>

DBCSCodePageEncoding은 Double Byte Character Set (DBCS) 코드 페이지 인코딩을

<#@ DirectiveName [AttributeName = "AttributeValue"] ... #> <# Standard control blocks #> 문장을 포함할 수 있습니다. <#= Expression control blocks # >표현식을 포함할 수 있습니다. <#+ Class feature control blocks #>메서드, 필드, 속성을 포함할 수 있습니다.

https://marketplace.visualstudio.com/items?itemName=bricelam.T4Language https://github.com/bricelam/T4Language

https://marketplace.visualstudio.com/items?itemName=bricelam.VSDataSqlite https://github.com/bricelam/VS.Data.Sqlite

<#@ template debug="false" hostspecific="false" language="C#" #> <#@ output extension=".cs" #>

hostspecific="true": 템플릿에서 호스트 애플리케이션의 환경 정보, 파일 경로 등 호스트와 관련된 정보를 사용할 수 있습니다. // ex) 템플릿이 실행되는 디렉터리 경로를 가져옴

Version

https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-version-history

• https://netpyoung.github.io/csharp-features/docs/

• https://stackoverflow.com/questions/247621/what-are-the-correct-version-numbers-for-c

• https://www.c-sharpcorner.com/article/c-sharp-versions/

9.0

top level statement

• https://learn.microsoft.com/en-us/dotnet/core/tutorials/top-level-templates
  • --use-program-main
  • <PropertyGroup> <ImplicitUsings>disable</ImplicitUsings> </PropertyGroup>
  • <ItemGroup> <Using Remove="System.Net.Http" /> </ItemGroup>

Tool

$ dotnet new tool-manifest
$ cat .config/dotnet-tools.json

$ dotnet tool install dotnet-format
$ cat .config/dotnet-tools.json

• dotnet-format
• coverlet.console
• dotnet-reportgenerator-globaltool
• microsoft.dotnet.xharness.cli
• microsoft.visualstudio.slngen.tool

Ref

• https://www.nuget.org/packages?packagetype=dotnettool
• https://github.com/dotnet/runtime/blob/main/.config/dotnet-tools.json

SourceGenerator

Analyzer

• roslyn-analyzers
• https://learn.microsoft.com/en-us/visualstudio/code-quality/roslyn-analyzers-overview
• FXCopAnalyzers
• StyleCopAnalyzers
• Security Code Scan
• Roslynator
• AsyncFixer
• Meziantou.Analyzer
• SerilogAnalyzer
• Microsoft.AspNetCore.Mvc.Api.Analyzers
• SonarAnalyzer.CSharp
  • https://www.sonarsource.com/products/sonarqube/
• NSubstitute.Analyzers.CSharp
• xunit.analyzers
• Microsoft.CodeQuality.Analyzers
• Microsoft.CodeAnalysis.VersionCheckAnalyzer
• ReSharper Command Line Tools

Ref

• https://github.com/bharatdwarkani/awesome-libraries-to-build-sass-application-dotnet-core