问关闭/断开ASP.NET核心signalR客户端连接的正确方法是什么？

EN

...
Logger.LogInformation("Closing secondary signalR connection...");
await hubConnection.StopAsync();
Logger.LogInformation("Closed secondary signalR connection");
...

#region Dispose
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }


        /// 
        /// Clear secondary signalR Closed event handler and stop the
        /// secondary signalR connection
        /// 
        /// 
        /// ASP.NET Core Release Candidate 5 calls DisposeAsync when 
        /// navigating away from a Blazor Server page. Until the 
        /// release is stable DisposeAsync will have to be triggered from
        /// Dispose. Sadly, this means having to use GetAwaiter().GetResult()
        /// in Dispose().
        /// However, providing DisposeAsync() now makes the migration easier
        /// https://github.com/dotnet/aspnetcore/issues/26737
        /// https://github.com/dotnet/aspnetcore/issues/9960
        /// https://github.com/dotnet/aspnetcore/milestone/57?closed=1
        /// 
        protected virtual void Dispose(bool disposing)
        {
            if (disposed)
                return;

            if (disposing)
            {
                Logger.LogInformation("Index.razor page is disposing...");

                try
                {
                    if (hubConnection != null)
                    {
                        Logger.LogInformation("Removing signalR client event handlers...");
                        hubConnection.Closed -= CloseHandler;
                    }

                    // Until ASP.NET Core 5 is released in November
                    // trigger DisposeAsync(). See docstring and DiposeAsync() below.
                    // not ideal, but having to use GetAwaiter().GetResult() until
                    // forthcoming release of ASP.NET Core 5 for the introduction
                    // of triggering DisposeAsync on pages that implement IAsyncDisposable
                    DisposeAsync().GetAwaiter().GetResult();
                }
                catch (Exception exception)
                {
                    Logger.LogError($"Exception encountered while disposing Index.razor page :: {exception.Message}");
                }
            }

            disposed = true;
        }


        /// 
        /// Dispose the secondary backend signalR connection
        /// 
        /// 
        /// ASP.NET Core Release Candidate 5 adds DisposeAsync when 
        /// navigating away from a Blazor Server page. Until the 
        /// release is stable DisposeAsync will have to be triggered from
        /// Dispose. Sadly, this means having to use GetAwaiter().GetResult()
        /// in Dispose().
        /// However, providing DisposeAsync() now makes the migration easier
        /// https://github.com/dotnet/aspnetcore/issues/26737
        /// https://github.com/dotnet/aspnetcore/issues/9960
        /// https://github.com/dotnet/aspnetcore/milestone/57?closed=1
        /// 
        public async virtual ValueTask DisposeAsync()
        {
            try
            {
                if (hubConnection != null)
                {
                    Logger.LogInformation("Closing secondary signalR connection...");
                    await hubConnection.StopAsync();
                    Logger.LogInformation("Closed secondary signalR connection");
                }
                // Dispose(); When migrated to ASP.NET Core 5 let DisposeAsync trigger Dispose
            }
            catch (Exception exception)
            {
                Logger.LogInformation($"Exception encountered wwhile stopping secondary signalR connection :: {exception.Message}");
            }
        }
        #endregion

using System;
using System.Threading.Tasks;

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.SignalR.Client;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

using WebApp.Data;
using WebApp.Data.Serializers.Converters;
using WebApp.Data.Serializers.Converters.Visitors;
using WebApp.Repository.Contracts;



namespace WebApp.Pages
{
    public partial class Index : IAsyncDisposable, IDisposable
    {
        private HubConnection hubConnection;
        public bool IsConnected => hubConnection.State == HubConnectionState.Connected;
        private bool disposed = false;


        [Inject]
        public NavigationManager NavigationManager { get; set; }
        [Inject]
        public IMotionDetectionRepository Repository { get; set; }
        [Inject]
        public ILogger LoggerMotionDetection { get; set; }
        [Inject]
        public ILogger LoggerMotionInfo { get; set; }
        [Inject]
        public ILogger LoggerJsonVisitor { get; set; }
        [Inject]
        public ILogger Logger { get; set; }


        #region Dispose
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }


        /// 
        /// Clear secondary signalR Closed event handler and stop the
        /// secondary signalR connection
        /// 
        /// 
        /// ASP.NET Core Release Candidate 5 calls DisposeAsync when 
        /// navigating away from a Blazor Server page. Until the 
        /// release is stable DisposeAsync will have to be triggered from
        /// Dispose. Sadly, this means having to use GetAwaiter().GetResult()
        /// in Dispose().
        /// However, providing DisposeAsync() now makes the migration easier
        /// https://github.com/dotnet/aspnetcore/issues/26737
        /// https://github.com/dotnet/aspnetcore/issues/9960
        /// https://github.com/dotnet/aspnetcore/milestone/57?closed=1
        /// 
        protected virtual void Dispose(bool disposing)
        {
            if (disposed)
                return;

            if (disposing)
            {
                Logger.LogInformation("Index.razor page is disposing...");

                try
                {
                    if (hubConnection != null)
                    {
                        Logger.LogInformation("Removing signalR client event handlers...");
                        hubConnection.Closed -= CloseHandler;
                    }

                    // Until ASP.NET Core 5 is released in November
                    // trigger DisposeAsync(). See docstring and DiposeAsync() below.
                    // not ideal, but having to use GetAwaiter().GetResult() until
                    // forthcoming release of ASP.NET Core 5 for the introduction
                    // of triggering DisposeAsync on pages that implement IAsyncDisposable
                    DisposeAsync().GetAwaiter().GetResult();
                }
                catch (Exception exception)
                {
                    Logger.LogError($"Exception encountered while disposing Index.razor page :: {exception.Message}");
                }
            }

            disposed = true;
        }


        /// 
        /// Dispose the secondary backend signalR connection
        /// 
        /// 
        /// ASP.NET Core Release Candidate 5 adds DisposeAsync when 
        /// navigating away from a Blazor Server page. Until the 
        /// release is stable DisposeAsync will have to be triggered from
        /// Dispose. Sadly, this means having to use GetAwaiter().GetResult()
        /// in Dispose().
        /// However, providing DisposeAsync() now makes the migration easier
        /// https://github.com/dotnet/aspnetcore/issues/26737
        /// https://github.com/dotnet/aspnetcore/issues/9960
        /// https://github.com/dotnet/aspnetcore/milestone/57?closed=1
        /// 
        public async virtual ValueTask DisposeAsync()
        {
            try
            {
                if (hubConnection != null)
                {
                    Logger.LogInformation("Closing secondary signalR connection...");
                    await hubConnection.StopAsync();
                    Logger.LogInformation("Closed secondary signalR connection");
                }
                // Dispose(); When migrated to ASP.NET Core 5 let DisposeAsync trigger Dispose
            }
            catch (Exception exception)
            {
                Logger.LogInformation($"Exception encountered wwhile stopping secondary signalR connection :: {exception.Message}");
            }
        }
        #endregion


        #region ComponentBase

        /// 
        /// Connect to the secondary signalR hub after rendering.
        /// Perform on the first render. 
        /// 
        /// 
        /// This could have been performed in OnInitializedAsync but
        /// that method gets executed twice when server prerendering is used.
        /// 
        protected override async Task OnAfterRenderAsync(bool firstRender)
        {
            if (firstRender)
            {
                var hubUrl = NavigationManager.BaseUri.TrimEnd('/') + "/motionhub";

                try
                {
                    Logger.LogInformation("Index.razor page is performing initial render, connecting to secondary signalR hub");

                    hubConnection = new HubConnectionBuilder()
                        .WithUrl(hubUrl)
                        .ConfigureLogging(logging =>
                        {
                            logging.AddConsole();
                            logging.AddFilter("Microsoft.AspNetCore.SignalR", LogLevel.Information);
                        })
                        .AddJsonProtocol(options =>
                        {
                            options.PayloadSerializerOptions = JsonConvertersFactory.CreateDefaultJsonConverters(LoggerMotionDetection, LoggerMotionInfo, LoggerJsonVisitor);
                        })
                        .Build();

                    hubConnection.On("ReceiveMotionDetection", ReceiveMessage);
                    hubConnection.Closed += CloseHandler;

                    Logger.LogInformation("Starting HubConnection");

                    await hubConnection.StartAsync();

                    Logger.LogInformation("Index Razor Page initialised, listening on signalR hub url => " + hubUrl.ToString());
                }
                catch (Exception e)
                {
                    Logger.LogError(e, "Encountered exception => " + e);
                }
            }
        }

        protected override async Task OnInitializedAsync()
        {
            await Task.CompletedTask;
        }
        #endregion


        #region signalR

        /// Log signalR connection closing
        /// 
        /// If an exception occurred while closing then this argument describes the exception
        /// If the signaR connection was closed intentionally by client or server, then this
        /// argument is null
        /// 
        private Task CloseHandler(Exception exception)
        {
            if (exception == null)
            {
                Logger.LogInformation("signalR client connection closed");
            }
            else
            {
                Logger.LogInformation($"signalR client closed due to error => {exception.Message}");
            }

            return Task.CompletedTask;
        }

        /// 
        /// Add motion detection notification to repository
        /// 
        /// Motion detection received via signalR
        private void ReceiveMessage(MotionDetection message)
        {
            try
            {
                Logger.LogInformation("Motion detection message received");

                Repository.AddItem(message);

                StateHasChanged();
            }
            catch (Exception ex)
            {
                Logger.LogError(ex, "An exception was encountered => " + ex.ToString());
            }
        }
        #endregion
    }
}

using System;
using System.Threading.Tasks;

using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Logging;


namespace WebApp.Realtime.SignalR
{
    /// 
    /// This represents endpoints available on the server, available for the
    /// clients to call
    /// 
    public class MotionHub : Hub
    {
        private bool _disposed = false;
        public ILogger Logger { get; set; }

        public MotionHub(ILogger logger) : base()
        {
            Logger = logger;
        }


        public override async Task OnConnectedAsync()
        {
            Logger.LogInformation($"OnConnectedAsync => Connection ID={Context.ConnectionId} : User={Context.User.Identity.Name}");
            await base.OnConnectedAsync();
        }

        public override async Task OnDisconnectedAsync(Exception exception)
        {
            if (exception != null)
            {
                Logger.LogInformation($"OnDisconnectedAsync => Connection ID={Context.ConnectionId} : User={Context.User.Identity.Name} : Exception={exception.Message}");
            }
            else
            {
                Logger.LogInformation($"OnDisconnectedAsync => Connection ID={Context.ConnectionId} : User={Context.User.Identity.Name}");
            }

            await base.OnDisconnectedAsync(exception);
        }

        // Protected implementation of Dispose pattern.
        protected override void Dispose(bool disposing)
        {
            if (_disposed)
            {
                return;
            }

            _disposed = true;

            // Call base class implementation.
            base.Dispose(disposing);
        }
    }
}