从BackgroundWorker的迁移到异步/ await方法 [英] Migrate from backgroundworker to async / await methods

问题描述

我一直在使用一个WinForms C＃应用程序BackgroundWorkers做任何WCF服务的数据呼叫象下面这样：

I have been using in a WinForms C# application BackgroundWorkers to do any WCF service data calls like below:

private void Worker_DoWork(object sender, DoWorkEventArgs e)
        {
            switch (_workerType)
            {
                case "search":


                    Data.SeekWCF seekWcf = new Data.SeekWCF();
                    _ds = seekWcf.SearchInvoiceAdmin(new Guid(cboEmployer.Value.ToString()), new Guid(cboGroup.Value.ToString()), txtSearchInvoiceNumber.Text, chkSearchLike.Checked, txtSearchFolio.Text, Convert.ToInt32(txtYear.Value));
                    seekWcf.Dispose();

                    break;

                case "update":

                    Data.AccountingWCF accWcf = new Data.AccountingWCF();
                    _returnVal = accWcf.UpdateInvoiceAdmin(_ds);
                    accWcf.Dispose();

                    break;
            }
        }

为了调用后台工作为我做例子：

In order to call the background worker I do for example:

private void btnSearch_Click(object sender, EventArgs e)
        {
            if (!_worker.IsBusy)
                {

                    ShowPleaseWait(Translate("Searching data. Please wait..."));
                    _workerType = "search";
                    _worker.RunWorkerAsync();
                }
        }

现在，我想开始迁移至任务（异步/等待）C＃5.0，所以我在这个例子中所做的是：

Now, I would like to start migrating to Task (async / await) C# 5.0, so what I did in this example was:

private async void ProcessSearch()
        {

            Data.SeekWCF seekWcf = new Data.SeekWCF();
            _ds = seekWcf.SearchInvoiceAdmin(new Guid(cboEmployer.Value.ToString()), new Guid(cboGroup.Value.ToString()), txtSearchInvoiceNumber.Text, chkSearchLike.Checked, txtSearchFolio.Text, Convert.ToInt32(txtYear.Value));
            seekWcf.Dispose();
        }

但在这里我得到一个消息，说此异步方法缺乏'等待'经营者和将同步运行。

But here I get a message saying that "this async method lacks 'await' operators and will run synchronously".

如何是最好的做法，这样做我想要完成什么？正道任何线索

Any clue on how is the best practice and the right way to do what I want to accomplish?

推荐答案

在理想情况下，你的WCF服务包装应该有它的方法异步版本，即 SearchInvoiceAdminAsync 。然后你会指日可待：

Ideally, your WCF service wrapper should have Async versions of its methods, i.e. SearchInvoiceAdminAsync. Then you'd await for it:

        private async Task ProcessSearchAsync()
        {

            Data.SeekWCF seekWcf = new Data.SeekWCF();
            _ds = await seekWcf.SearchInvoiceAdminAsync(new Guid(cboEmployer.Value.ToString()), new Guid(cboGroup.Value.ToString()), txtSearchInvoiceNumber.Text, chkSearchLike.Checked, txtSearchFolio.Text, Convert.ToInt32(txtYear.Value));
            seekWcf.Dispose();
        }

编辑：一个不同的问题是，最终你需要从一个普通的方法调用您的异步方法，例如，在点击一个按钮，也许当任务完成后做一些事情。这里是一个非常简单的场景：

EDITED: A different matter is that eventually you'd need to call your async method from a regular method, e.g, upon a button click, and perhaps do something when the task is done. Here is a very simplistic scenario:

// UI Thread

Task _pendingTask = null;

void button_click()
{
    if ( _pendingTask != null)
    {
        MessageBox.Show("Still working!");
    }
    else
    {
        _pendingTask = ProcessSearchAsync();


        _pendingTask.ContinueWith((t) =>
        {
            MessageBox.Show("Task is done!");
            // check _pendingTask.IsFaulted here
            _pendingTask = null;
        }, TaskScheduler.FromCurrentSynchronizationContext());
    }
}

编辑：注意，一开始我忘了指定时调用的TaskScheduler ContinueWith 。这可能导致 continuationAction 被称为一个线程池

EDITED: Note, initially I forgot to specify TaskScheduler when calling ContinueWith. That might have resulted in continuationAction being called on a pool thread.

这篇关于从BackgroundWorker的迁移到异步/ await方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！