如何知道异步方法是否正在运行

Question

我有一个按钮，点击事件会从服务器获取数据并将其显示在网格上。

代码如下：

private void btnSearch_Click(object sender, EventArgs e)
{
    // Here I should do something in order to know if the async ProcessSearch method is busy..
    // if not busy then I will execute it if not then I will return.
    // shows loading animation
    ShowPleaseWait(Translate("Searching data. Please wait..."));
    ProcessSearch();
}

private async void ProcessSearch()
{
    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();

    if (_ds != null)
    {
        SetupInvoiceGrid();
    }
    // hides the loading animation
    HidePleaseWait();
}

我如何知道异步方法 ProcessSearch 是忙还是正在运行，这样我就可以防止用户在再次单击按钮时再次执行该方法。

Answer 1

你可以设置一个布尔值：

private bool isSearching = false;

private void btnSearch_Click(object sender, EventArgs e)
{
    if (isSearching)
        return;
    // shows loading animation
    ShowPleaseWait(Translate("Searching data. Please wait..."));
    ProcessSearch();
}

private async void ProcessSearch()
{
    isSearching = true;

    // do other stuff

    isSearching = false;
}

如果您担心并发，可以添加lock：

private bool isSearching = false;
private object lockObj = new object();

private void btnSearch_Click(object sender, EventArgs e)
{
    lock (lockObj)
    {
        if (isSearching)
            return;
        else
            isSearching = true;
    }
    // shows loading animation
    ShowPleaseWait(Translate("Searching data. Please wait..."));
    ProcessSearch();
}

private async void ProcessSearch()
{
    // do other stuff

    isSearching = false;
}