异步添加Bindinglist/Cross-threading&Locking问题的价值

Question

我有一个BindingList数据绑定到datgridview.我用它来跟踪一些实时价格.各种线程每秒多次调用方法'update(Quote quote)'.如果datagridview不包含Quote,则添加它.如果是,则更新报价的值.我不希望在BindingList(或GUI)上出现两次相同的引用,所以我试图锁定检查值是否在列表中的操作.它不起作用!我究竟做错了什么？我尝试了两种不同的锁定方式,并锁定了一个String对象,而不仅仅是一个对象.问题肯定在BeginInvoke(new MethodInvoker(delegate() { activeQuotes.Insert(0, quote); }));调用中(这可能需要一些时间),但是如果我将其设置为同步,则"add"方法会抛出"交叉线程"错误...我该怎么做才能避免交叉线程错误,但确保锁也可以工作？

public BindingList<Quote> activeQuotes = new BindingList<Quote>();
object lockObject = "lockObject";

dataGridViewActive.DataSource = activeQuotes;


public void update(Quote quote)
{
//lock (lockObject)
if(Monitor.TryEnter(lockObject))
{
try
   {
    if (!activeQuotes.Contains(quote))
    {
       try
       {
          activeQuotes.Add(quote);
          AddQuote(quote);
       }
       catch (Exception ex)
       {
          Console.WriteLine("Datagridview!!!!!!");
       }
     }
 else
 {
   int index = activeQuotes.IndexOf(quote);
   activeQuotes[index].Bid = quote.Bid;
   activeQuotes[index].Ask = quote.Ask;
   activeQuotes[index].Mid = quote.Mid;
   activeQuotes[index].Spread = quote.Spread;
   activeQuotes[index].Timestamp = quote.Timestamp;
}
finally
{
    Monitor.Exit(lockObject);
}
}

private void AddQuote(Quote quote)
{
     if (this.InvokeRequired)
     {
                BeginInvoke(new MethodInvoker(delegate() { activeQuotes.Insert(0, quote); }));
                BeginInvoke(new MethodInvoker(delegate() { dataGridViewActive.Refresh(); }));
                BeginInvoke(new MethodInvoker(delegate() { dataGridViewActive.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.AllCells); }));
    }
    else
    {
                activeQuotes.Add(quote);
                dataGridViewActive.Refresh();
                dataGridViewActive.AutoResizeColumns (DataGridViewAutoSizeColumnsMode.AllCells);
     }
}

我对此表示感谢.

谢谢.

Answer 1

我之前写过的这段代码会做

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        BindingListInvoked<Name> names;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            names = new BindingListInvoked<Name>(dataGridView1);

            dataGridView1.DataSource = names;

            new Thread(() => names.Add(new Name() { FirstName = "Larry", LastName = "Lan" })).Start();
            new Thread(() => names.Add(new Name() { FirstName = "Jessie", LastName = "Feng" })).Start();
        }
    }

    public class BindingListInvoked<T> : BindingList<T>
    {
        public BindingListInvoked() { }

        private ISynchronizeInvoke _invoke;
        public BindingListInvoked(ISynchronizeInvoke invoke) { _invoke = invoke; }
        public BindingListInvoked(IList<T> items) { this.DataSource = items; }
        delegate void ListChangedDelegate(ListChangedEventArgs e);

        protected override void OnListChanged(ListChangedEventArgs e)
        {

            if ((_invoke != null) && (_invoke.InvokeRequired))
            {
                IAsyncResult ar = _invoke.BeginInvoke(new ListChangedDelegate(base.OnListChanged), new object[] { e });
            }
            else
            {
                base.OnListChanged(e);
            }
        }
        public IList<T> DataSource
        {
            get
            {
                return this;
            }
            set
            {
                if (value != null)
                {
                    this.ClearItems();
                    RaiseListChangedEvents = false;

                    foreach (T item in value)
                    {
                        this.Add(item);
                    }
                    RaiseListChangedEvents = true;
                    OnListChanged(new ListChangedEventArgs(ListChangedType.Reset, -1));
                }
            }
        }
    }

    public class Name
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
}