数据链接对象具有空闲状态,必须等待以下四种情况之一：

>收到一个字节
>网络线程提供了一条消息
>保持活动计时器已过期
>所有通信都被网络层取消

我很难找到最好的方法来实现这一点,而无需将通信分成读/写线程(从而大大增加了复杂性).以下是我如何获得4分中的3分：

// Read a byte from 'stream'. Timeout after 10 sec. Monitor the cancellation token.
stream.ReadTimeout = 10000;
await stream.ReadAsync(buf,1,cts.Token);

要么

BlockingCollection<byte[]> SendQueue = new ...;
...
// Check for a message from network layer. Timeout after 10 seconds.
// Monitor cancellation token.
SendQueue.TryTake(out msg,10000,cts.Token);

我该怎么做才能阻止线程,等待所有四个条件？欢迎所有建议.我没有设置任何架构或数据结构.

编辑：********感谢大家的帮助.这是我的解决方案********

首先,我认为没有生产者/消费者队列的异步实现.所以我实现了类似于this stackoverflow post的东西.

我需要一个外部和内部取消源来分别停止使用者线程并取消中间任务,similar to this article.

byte[] buf = new byte[1];
using (CancellationTokenSource internalTokenSource = new CancellationTokenSource())
{
    CancellationToken internalToken = internalTokenSource.Token;
    CancellationToken stopToken = stopTokenSource.Token;
    using (CancellationTokenSource linkedCts =
        CancellationTokenSource.CreateLinkedTokenSource(stopToken,internalToken))
    {
        CancellationToken ct = linkedCts.Token;
        Task<int> readTask = m_stream.ReadAsync(buf,ct);
        Task<byte[]> msgTask = m_sendQueue.DequeueAsync(ct);
        Task keepAliveTask = Task.Delay(m_keepAliveTime,ct);

        // Wait for at least one task to complete
        await Task.WhenAny(readTask,msgTask,keepAliveTask);

        // Next cancel the other tasks
        internalTokenSource.Cancel();
        try {
            await Task.WhenAll(readTask,keepAliveTask);
        } catch (OperationCanceledException e) {
            if (e.CancellationToken == stopToken)
                throw;
        }

        if (msgTask.IsCompleted)
            // Send the network layer message
        else if (readTask.IsCompleted)
            // Process the byte from the physical layer
        else
            Contract.Assert(keepAliveTask.IsCompleted);
            // Send a keep alive message
    }
}

解决方法

CancellationToken token = ...;

var readByteTask = stream.ReadAsync(buf,token);

var keepAliveTimerTask = Task.Delay(TimeSpan.FromSeconds(10),token);

BufferBlock<byte[]> SendQueue = new ...;
...
var messageTask = SendQueue.ReceiveAsync(token);

var completedTask = await Task.WhenAny(readByteTask,keepAliveTimerTask,messageTask);

if (completedTask == readByteTask)
{
  // Throw an exception if there was a read error or cancellation.
  await readByteTask;
  var byte = buf[0];
  ...
  // Continue reading
  readByteTask = stream.ReadAsync(buf,token);
}
else if (completedTask == keepAliveTimerTask)
{
  // Throw an exception if there was a cancellation.
  await keepAliveTimerTask;
  ...
  // Restart keepalive timer.
  keepAliveTimerTask = Task.Delay(TimeSpan.FromSeconds(10),token);
}
else if (completedTask == messageTask)
{
  // Throw an exception if there was a cancellation (or the SendQueue was marked as completed)
  byte[] message = await messageTask;
  ...
  // Continue reading
  messageTask = SendQueue.ReceiveAsync(token);
}

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