C#中间件如何管理WebSocket会话池

在C#中，要管理WebSocket会话池，你需要创建一个类来存储和处理所有活动的WebSocket连接。以下是一个简单的示例，展示了如何使用中间件来管理WebSocket会话池：

1. 首先，安装Microsoft.AspNetCore.WebSockets包：

dotnet add package Microsoft.AspNetCore.WebSockets

2. 创建一个WebSocketSession类，用于存储WebSocket连接信息：

public class WebSocketSession
{
    public string Id { get; set; }
    public WebSocket WebSocket { get; set; }
}

3. 创建一个WebSocketSessionManager类，用于管理WebSocket会话池：

public class WebSocketSessionManager
{
    private ConcurrentDictionary<string, WebSocketSession> _sessions = new ConcurrentDictionary<string, WebSocketSession>();

    public void AddSession(WebSocketSession session)
    {
        _sessions.TryAdd(session.Id, session);
    }

    public void RemoveSession(string id)
    {
        _sessions.TryRemove(id, out _);
    }

    public WebSocketSession GetSessionById(string id)
    {
        _sessions.TryGetValue(id, out var session);
        return session;
    }

    public List<WebSocketSession> GetAllSessions()
    {
        return _sessions.Values.ToList();
    }
}

4. 创建一个中间件来处理WebSocket请求：

public class WebSocketMiddleware
{
    private readonly RequestDelegate _next;
    private readonly WebSocketSessionManager _sessionManager;

    public WebSocketMiddleware(RequestDelegate next, WebSocketSessionManager sessionManager)
    {
        _next = next;
        _sessionManager = sessionManager;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.WebSockets.IsWebSocketRequest)
        {
            var webSocket = await context.WebSockets.AcceptWebSocketAsync();
            var session = new WebSocketSession
            {
                Id = Guid.NewGuid().ToString(),
                WebSocket = webSocket
            };

            _sessionManager.AddSession(session);

            try
            {
                await HandleWebSocketSession(session);
            }
            finally
            {
                _sessionManager.RemoveSession(session.Id);
            }
        }
        else
        {
            await _next(context);
        }
    }

    private async Task HandleWebSocketSession(WebSocketSession session)
    {
        var buffer = new byte[1024 * 4];
        var result = await session.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

        while (!result.CloseStatus.HasValue)
        {
            // Process received data
            // ...

            // Send data to client
            // ...

            result = await session.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
        }

        await session.WebSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
    }
}

5. 在Startup类中注册中间件和WebSocketSessionManager：

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<WebSocketSessionManager>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseWebSockets();
        app.UseMiddleware<WebSocketMiddleware>();

        // Other middlewares
        // ...
    }
}

现在，你已经创建了一个可以管理WebSocket会话池的中间件。你可以通过WebSocketSessionManager类的实例来访问和操作所有活动的WebSocket连接。