[Route("api/[controller]/[action]")]
[ApiController]
public class InformationController : ControllerBase
{
    private readonly LibraryContext _libraryContext;
    private readonly IServiceProvider _serviceProvider;
    private readonly ILogger<InformationController> _logger;

    public InformationController(LibraryContext libraryContext, 
        IServiceProvider serviceProvider,
        ILogger<InformationController> logger)
    {
        _libraryContext = libraryContext;
        _serviceProvider = serviceProvider;
        _logger = logger;
    }

    [HttpGet]
    public string GetFirst()
    {
        var caseInfo = _libraryContext.Informations.Where(i => i.IsDelete == 0).FirstOrDefault();
        //這里直接使用了Task方式
        Task.Run(() => {
            try
            {
                //Task里創(chuàng)建了新的IServiceScope
                using var scope = _serviceProvider.CreateScope();
                //通過IServiceScope創(chuàng)建具體實(shí)例
                LibraryContext dbContext = scope.ServiceProvider.GetService<LibraryContext>();
                var list = dbContext!.Informations.Where(i => i.IsDelete == 0).Take(100).ToList();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex.Message, ex);
            }
        });
        return caseInfo.Title;
    }
}

[HttpGet]
public async Task<string> GetFirst()
{
    var caseInfo = _libraryContext.Informations.Where(i => i.IsDelete == 0).FirstOrDefault();
    //這里使用了await Task方式
    await Task.Run(() => {
        try
        {
            //Task里創(chuàng)建了新的IServiceScope
            using var scope = _serviceProvider.CreateScope();
            //通過IServiceScope創(chuàng)建具體實(shí)例
            LibraryContext dbContext = scope.ServiceProvider.GetService<LibraryContext>();
            var list = dbContext!.Informations.Where(i => i.IsDelete == 0).Take(100).ToList();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex.Message, ex);
        }
    });
    return caseInfo.Title;
}

[Route("api/[controller]/[action]")]
[ApiController]
public class InformationController : ControllerBase
{
    private readonly LibraryContext _libraryContext;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<InformationController> _logger;

    public InformationController(LibraryContext libraryContext, 
        IServiceScopeFactory scopeFactory,
        ILogger<InformationController> logger)
    {
        _libraryContext = libraryContext;
        _scopeFactory = scopeFactory;
        _logger = logger;
    }

    [HttpGet]
    public string GetFirst()
    {
        var caseInfo = _libraryContext.Informations.Where(i => i.IsDelete == 0).FirstOrDefault();
        //這里直接使用了Task方式
        Task.Run(() => {
            try
            {
                //Task里創(chuàng)建了新的IServiceScope
                using var scope = _scopeFactory.CreateScope();
                //通過IServiceScope創(chuàng)建具體實(shí)例
                LibraryContext dbContext = scope.ServiceProvider.GetService<LibraryContext>();
                var list = dbContext!.Informations.Where(i => i.IsDelete == 0).Take(100).ToList();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex.Message, ex);
            }
        });
        return caseInfo.Title;
    }
}

internal class DefaultControllerActivator : IControllerActivator
{
    private readonly ITypeActivatorCache _typeActivatorCache;
    public DefaultControllerActivator(ITypeActivatorCache typeActivatorCache)
    {
        _typeActivatorCache = typeActivatorCache;
    }

    public object Create(ControllerContext controllerContext)
    {
        //省略一系列判斷代碼

        var serviceProvider = controllerContext.HttpContext.RequestServices;
        //這里傳遞的IServiceProvider本質(zhì)就是來自HttpContext.RequestServices
        return _typeActivatorCache.CreateInstance<object>(serviceProvider, controllerTypeInfo.AsType());
    }
}

internal class TypeActivatorCache : ITypeActivatorCache
{
    private readonly Func<Type, ObjectFactory> _createFactory =
        (type) => ActivatorUtilities.CreateFactory(type, Type.EmptyTypes);
    private readonly ConcurrentDictionary<Type, ObjectFactory> _typeActivatorCache =
            new ConcurrentDictionary<Type, ObjectFactory>();

    public TInstance CreateInstance<TInstance>(
        IServiceProvider serviceProvider,
        Type implementationType)
    {
        //省略一系列判斷代碼

        var createFactory = _typeActivatorCache.GetOrAdd(implementationType, _createFactory);
        //創(chuàng)建Controller的時(shí)候，需要的依賴實(shí)例都是來自IServiceProvider
        return (TInstance)createFactory(serviceProvider, arguments: null);
    }
}

[Route("api/[controller]/[action]")]
[ApiController]
public class InformationController : ControllerBase
{
    private readonly IServiceProvider _serviceProvider;

    public InformationController(IServiceProvider serviceProvider)
    {
        _serviceProvider = serviceProvider;
    }

    [HttpGet]
    public bool[] JudgeScope([FromServices]IServiceProvider scopeProvider)
    {
        //比較構(gòu)造注入的和在HttpContext獲取的
        bool isEqualOne = _serviceProvider == HttpContext.RequestServices;
        //比較通過Action綁定的和在HttpContext獲取的
        bool isEqualTwo = scopeProvider == HttpContext.RequestServices;
        return new[] { isEqualOne, isEqualTwo };
    }
}

//接受
public IServiceScopeFactory ServiceScopeFactory { get; set; } = default!;
//數(shù)據(jù)來自RequestServicesFeature
private static readonly Func<DefaultHttpContext, IServiceProvidersFeature> _newServiceProvidersFeature = context => new RequestServicesFeature(context, context.ServiceScopeFactory);
//緩存來自_newServiceProvidersFeature
private IServiceProvidersFeature ServiceProvidersFeature =>
            _features.Fetch(ref _features.Cache.ServiceProviders, this, _newServiceProvidersFeature)!;
//數(shù)據(jù)來自ServiceProvidersFeature的RequestServices
public override IServiceProvider RequestServices
{
    get { return ServiceProvidersFeature.RequestServices; }
    set { ServiceProvidersFeature.RequestServices = value; }
}

public class RequestServicesFeature : IServiceProvidersFeature, IDisposable, IAsyncDisposable
{
    private readonly IServiceScopeFactory? _scopeFactory;
    private IServiceProvider? _requestServices;
    private IServiceScope? _scope;
    private bool _requestServicesSet;
    private readonly HttpContext _context;

    public RequestServicesFeature(HttpContext context, IServiceScopeFactory? scopeFactory)
    {
        _context = context;
        _scopeFactory = scopeFactory;
    }

    public IServiceProvider RequestServices
    {
        get
        {
            if (!_requestServicesSet && _scopeFactory != null)
            {
                //釋放掉之前沒釋放掉的RequestServicesFeature實(shí)例
                _context.Response.RegisterForDisposeAsync(this);
                //通過IServiceScopeFactory創(chuàng)建Scope
                _scope = _scopeFactory.CreateScope();
                //RequestServices來自IServiceScopeFactory的CreateScope實(shí)例
                _requestServices = _scope.ServiceProvider;
                //填充已經(jīng)設(shè)置了RequestServices的標(biāo)識(shí)
                _requestServicesSet = true;
            }
            return _requestServices!;
        }
        set
        {
            _requestServices = value;
            _requestServicesSet = true;
        }
    }

    //釋放的真實(shí)邏輯
    public ValueTask DisposeAsync()
    {
        switch (_scope)
        {
            case IAsyncDisposable asyncDisposable:
                var vt = asyncDisposable.DisposeAsync();
                if (!vt.IsCompletedSuccessfully)
                {
                    return Awaited(this, vt);
                }
                
                vt.GetAwaiter().GetResult();
                break;
            case IDisposable disposable:
                disposable.Dispose();
                break;
        }
        //釋放時(shí)重置相關(guān)屬性
        _scope = null;
        _requestServices = null;

        return default;

        static async ValueTask Awaited(RequestServicesFeature servicesFeature, ValueTask vt)
        {
            await vt;
            servicesFeature._scope = null;
            servicesFeature._requestServices = null;
        }
    }
    //IDisposable的Dispose的方法，通過using可隱式調(diào)用
    public void Dispose()
    {
        DisposeAsync().AsTask().GetAwaiter().GetResult();
    }
}

public class DefaultHttpContextFactory : IHttpContextFactory
{
    private readonly IHttpContextAccessor? _httpContextAccessor;
    private readonly FormOptions _formOptions;
    private readonly IServiceScopeFactory _serviceScopeFactory;

    public DefaultHttpContextFactory(IServiceProvider serviceProvider)
    {
        _httpContextAccessor = serviceProvider.GetService<IHttpContextAccessor>();
        _formOptions = serviceProvider.GetRequiredService<IOptions<FormOptions>>().Value;
        //通過IServiceProvider的GetRequiredService直接獲取IServiceScopeFactory
        _serviceScopeFactory = serviceProvider.GetRequiredService<IServiceScopeFactory>();
    }

    //創(chuàng)建HttpContext實(shí)例的方法
    public HttpContext Create(IFeatureCollection featureCollection)
    {
        if (featureCollection is null)
        {
            throw new ArgumentNullException(nameof(featureCollection));
        }

        var httpContext = new DefaultHttpContext(featureCollection);
        Initialize(httpContext);
        return httpContext;
    }

    private DefaultHttpContext Initialize(DefaultHttpContext httpContext)
    {
        //IHttpContextAccessor也是在這里賦的值
        if (_httpContextAccessor != null)
        {
            _httpContextAccessor.HttpContext = httpContext;
        }

        httpContext.FormOptions = _formOptions;
        //DefaultHttpContext的ServiceScopeFactory屬性值來自注入的IServiceProvider
        httpContext.ServiceScopeFactory = _serviceScopeFactory;

        return httpContext;
    }
}

services.TryAddSingleton<IHttpContextFactory, DefaultHttpContextFactory>();

[HttpGet("/fire-and-forget-3")]
public IActionResult FireAndForget3([FromServices]IServiceScopeFactory serviceScopeFactory)
{
    _ = Task.Run(async () =>
    {
        await Task.Delay(1000);

        using (var scope = serviceScopeFactory.CreateScope())
        {
            var context = scope.ServiceProvider.GetRequiredService<ContosoDbContext>();
            context.Contoso.Add(new Contoso());
            await context.SaveChangesAsync();                                        
        }
    });

    return Accepted();
}