Question

在我的WPF项目中。我有：

public partial class MainWindow : Window
{
    ObservableCollection<Calls> items = new ObservableCollection<Calls>();
public MainWindow()
{
    InitializeComponent();
    icTodoList.ItemsSource = items;
    this.DataContext = new MainViewModel();
}

icTodoList是ItemsControl，我想为其添加两列。

<DockPanel>
<ItemsControl Height="300" Name="icTodoList" ItemsSource="{Binding Calls}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="60"/>
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>

                <TextBlock Text="{Binding DialingNumber, Mode=OneWay, FallbackValue=' '}" Grid.Column="0"/>
                <TextBlock Text="{Binding DialResult, Mode=OneWay, FallbackValue=' '}" Grid.Column="1"/>
            </Grid>
        </DataTemplate>

    </ItemsControl.ItemTemplate>
</ItemsControl></DockPanel>

对于Calls类，我们有

public class Calls : NotifyUIBase
{
    private string dialingNumber;
    public string DialingNumber
    {
        get { return dialingNumber; }
        set
        {
            dialingNumber = value;
            RaisePropertyChanged();
        }
    }
    public string dialResult;
    public string DialResult {
        get { return dialResult; }
        set
        {
            dialResult = value;
            RaisePropertyChanged();
        }
    }
}

NotifyUIBase继承自INotifyPropertyChanged，它包含RaisePropertyChanged属性，忽略此处写入以节省空间。

现在，点击Start按钮即可获得生产者 - 消费者流程。

    private async void Start_Click(object sender, RoutedEventArgs e)
    {
        var producer = Producer();
        var consumer = Consumer();
        await Task.WhenAll(producer, consumer);
    }

在consumer方法中，我们更新ItemsControl。

async Task Consumer()
{
    try
    {
        var executionDataflowBlockOptions = new ExecutionDataflowBlockOptions
        {
            MaxDegreeOfParallelism = 50
        };
        var consumerBlock = new ActionBlock<AppointmentReminder>(
remainder =>
{
   Calls c = new Calls();
   c.DialingNumber = "number..";
   c.DialResult = "result...;
   items.Add(c);
},
executionDataflowBlockOptions);
 bufferBlock.LinkTo(
 consumerBlock, new DataflowLinkOptions { PropagateCompletion = true });
                await Task.Delay(500);
          }

然而我有一个例外：

这种类型的CollectionView不支持从与Dispatcher线程不同的线程更改其SourceCollection。

发生在这一行：

items.Add（C）;

我想这是线程问题，所以如何解决？

Answer 1

您已经将一些选项传递给ActionBlock;您可以在那里轻松指定UI调度程序：

var executionDataflowBlockOptions = new ExecutionDataflowBlockOptions
{
  TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext(),
};

请注意，它不再并行运行。如果您的操作代码很简单（创建单个对象并设置几个属性），这应该足够了。但是，如果对象创建是CPU密集型的，您可能希望保持并行性：

var transformOptions = new ExecutionDataflowBlockOptions
{
  MaxDegreeOfParallelism = 50
};
var actionOptions = new ExecutionDataflowBlockOptions
{
  TaskScheduler = TaskScheduler.FromCurrentSynchronizationContext(),
};
var transformBlock = new TransformBlock<AppointmentReminder, Calls>(reminder =>
{
  Calls c = new Calls();
  c.DialingNumber = "number..";
  c.DialResult = "result...;
  return c;
}, transformOptions);
var consumerBlock = new ActionBlock<Calls>(c =>
{
  items.Add(c);
}, actionOptions);
var linkOptions = new DataflowLinkOptions { PropagateCompletion = true };
bufferBlock.LinkTo(transformBlock, linkOptions);
transformBlock.LinkTo(consumerBlock, linkOptions);

Answer 2

只需获取您的项目。在UI线程上执行添加调用：

remainder =>
{
   Calls c = new Calls();
   c.DialingNumber = "number..";
   c.DialResult = "result...;
   Dispatcher.Invoke(()=> // Get the dispatcher from your window and use it here
   {
       items.Add(c);
   }
},

Answer 3

在CP上查看Asynchronous Multi-threaded ObservableCollection结束。

我在我的所有项目中使用它，并且从多个TPL线程中添加项目或项目范围从未出现任何问题......

在TPL中安全地添加集合

3 个答案: