问题描述

我之前有一个问题，我已经提供了我的解决方案；但是，由于我使用的是 .Net 3.5，因此我无法访问 ConcurrentQueue<T>.我需要 Queue<T> 来允许并发.我读了这个 问题，如果一个项目是 不在队列中，并且线程方法尝试使项目出队.

I have a previous question which I have provided my solution; however, I don't have access to ConcurrentQueue<T> since I am on .Net 3.5. I need Queue<T> to allow concurrency. I read this question and seems to present a problem if an item is not in the queue and the threaded method tries to dequeue an item.

我现在的任务是确定我是否可以派生我自己的并发队列类.这是我想出的:

My task now is to determine whether I can derive my own concurrent Queue class. This is what I came up with:

public sealed class ConcurrentQueue : Queue<DataTable>
{
    public event EventHandler<TableQueuedEventArgs> TableQueued;
    private ICollection que;

    new public void Enqueue(DataTable Table)
    {
        lock (que.SyncRoot)
        {
            base.Enqueue(Table);
        }

        OnTableQueued(new TableQueuedEventArgs(Dequeue()));
    }

    //  this is where I think I will have a problem...
    new public DataTable Dequeue()
    {
        DataTable table;

        lock (que.SyncRoot)
        {
            table = base.Dequeue();
        }

        return table;
    }

    public void OnTableQueued(TableQueuedEventArgs table)
    {
        EventHandler<TableQueuedEventArgs> handler = TableQueued;

        if (handler != null)
        {
            handler(this, table);
        }
    }
}

因此，当 DataTable 排队时，EventArgs 会将出队的表传递给事件订阅者.这个实现会为我提供一个线程安全的队列吗?

So, when a DataTable is queued, the EventArgs will pass a dequeued table to the event subscriber. Will this implementation provide me with a thread-safe Queue?

推荐答案

您在将项目入队时将其出队.
您需要使用您的参数引发事件.

You're dequeueing your items as you enqueue them.
You need to raise the event using your parameter.

它是否真的是线程安全的取决于你如何使用它.
如果您曾经检查过 Count 或检查是否为空，则它不是线程安全的，也不能轻易地成为线程安全的.
如果你不这样做，你可能可以使用比队列更简单的东西.

Whether it's actually thread-safe depends on how you use it.
If you ever check the Count or check for emptiness, it's not threadsafe and cannot easily be made threadsafe.
If you don't, you can probably use something simpler than a queue.

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