Loop asynchronous calls and process data at the end of all executions

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Loop asynchronous calls and process data at the end of all executions

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#1 by (2 votes)

3

I have a method of a web service that receives the IP of a server as a parameter and returns a DataSet . Multiple servers must be queried by this web service, A List<string> contains the list of IPs. A loop executes the method, a merge is returned to a local DataSet, and then a% winforms is populated with that data.

The code that does this is simple:

    foreach (var server in servers)
    {
        ds.Merge(ws.GetData(server));
    }

    dataGridView1.DataSource = ds.Tables[0];

This call runs in a queue and takes a while to finish, in addition to locking the entire form.

How can I convert this process to an asynchronous form using the DataGridView method with GetDataAsync and async to execute all calls at once and display the data in Task at the end?

c# multithreading async winforms

asked by anonymous 26.02.2014 / 15:57

1 answer

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score 2 · Accepted Answer

Do this:

var tasks = servers.Select(server => ws.GetDataAsync(server)).ToArray();
Task.WaitAll(tasks);
var results = tasks.SelectMany(t => t.Result).ToList();
foreach (var res in results)
    ds.Merge(res);

If the method in which the code exists (eg an event of a windows forms control) can be declared with async , it could still use await and leave execution of the whole block after await for when all results are ready:

private async Task EventoDoForm(EventArgs e)
{
    var tasks = servers.Select(server => ws.GetDataAsync(server)).ToArray();
    await Task.WhenAll(tasks);
    var results = tasks.SelectMany(t => t.Result).ToList();
    foreach (var res in results)
        ds.Merge(res);
}

So, the event will not crash form.