我的 c# 8.0 using 声明会正确处理我的对象吗？什么时候处置？

Question

当它为真时，我在循环中调用以下方法，这会导致自动重新连接。由于我使用关键字using，它是在每个客户端上处置 ClientWebSockettry/catch return false还是仅在到达 ConnectAsync 末尾时才处置它？

private async Task<bool> ConnectAsync(CancellationToken cancellationToken)
{
    using var clientWebSocket = new ClientWebSocket(); // TODO: Check if it's actually disposed
    _clientWebSocket = clientWebSocket;

    try
    {
        await clientWebSocket.ConnectAsync(new Uri(_url), cancellationToken);
    }
    catch
    {
        return false;
    }

    try
    {
        while (clientWebSocket.State == WebSocketState.Open && !cancellationToken.IsCancellationRequested)
        {
            var bytesReceived = new ArraySegment<byte>(new byte[1024]);
            var receiveResult = await clientWebSocket.ReceiveAsync(bytesReceived, cancellationToken);
            var message = Encoding.UTF8.GetString(bytesReceived.Array, 0, receiveResult.Count);
            
            ...
        }
    }
    catch
    {
        return false;
    }

    try
    {
        if (clientWebSocket.State == WebSocketState.Open)
        {
            await clientWebSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "bye", CancellationToken.None);
        }
    }
    catch
    {
        return false;
    }

    return true;
}

Answer 1

using var clientWebSocket = new ClientWebSocket();只是语法糖，它是以下内容的缩写：

private async Task<bool> ConnectAsync(CancellationToken cancellationToken)
{
    using( var clientWebSocket = new ClientWebSocket())
    {
        _clientWebSocket = clientWebSocket;

        try
        {
            await clientWebSocket.ConnectAsync(new Uri(_url), cancellationToken);
        }
        catch
        {
            return false;
        }

        try
        {
            while (clientWebSocket.State == WebSocketState.Open && !cancellationToken.IsCancellationRequested)
            {
                var bytesReceived = new ArraySegment<byte>(new byte[1024]);
                var receiveResult = await clientWebSocket.ReceiveAsync(bytesReceived, cancellationToken);
                var message = Encoding.UTF8.GetString(bytesReceived.Array, 0, receiveResult.Count);
                
                ...
            }
        }
        catch
        {
            return false;
        }

        try
        {
            if (clientWebSocket.State == WebSocketState.Open)
            {
                await clientWebSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "bye", CancellationToken.None);
            }
        }
        catch
        {
            return false;
        }

        return true;

    }
}

这是以下内容的简写：

private async Task<bool> ConnectAsync(CancellationToken cancellationToken)
{
    var clientWebSocket = new ClientWebSocket();
    try
    {
        _clientWebSocket = clientWebSocket;

        try
        {
            await clientWebSocket.ConnectAsync(new Uri(_url), cancellationToken);
        }
        catch
        {
            return false;
        }

        try
        {
            while (clientWebSocket.State == WebSocketState.Open && !cancellationToken.IsCancellationRequested)
            {
                var bytesReceived = new ArraySegment<byte>(new byte[1024]);
                var receiveResult = await clientWebSocket.ReceiveAsync(bytesReceived, cancellationToken);
                var message = Encoding.UTF8.GetString(bytesReceived.Array, 0, receiveResult.Count);
                
                ...
            }
        }
        catch
        {
            return false;
        }

        try
        {
            if (clientWebSocket.State == WebSocketState.Open)
            {
                await clientWebSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "bye", CancellationToken.None);
            }
        }
        catch
        {
            return false;
        }

        return true;

    }
    finally
    {
        if (clientWebSocket != null) {
            ((IDisposable)clientWebSocket).Dispose();  
        }
    }
}

我认为还值得强调此评论：

我更担心您正在处理分配给 _clientWebSocket 字段的内容

clientWebSocket将被释放，但因为你分配_clientWebSocket给 this ( _clientWebSocket = clientWebSocket;)，varibale 指向的对象也将被释放！他们是一样的东西。他们互相引用。我想这不是您希望在这里发生的情况，但从您共享的代码中很难看出。