csharp-async.md

basic

// return Task all the time
public async Task DoWorkAsync(int parameter)
{
  await Task.Delay(parameter);
  Console.WriteLine("Awiated the delayed time");
}

// composition of async task
public async Task<double> GetSumAsync()
{
    var left = await GetNumberAsync();
    var right = await GetNumberAsync();
    
    return left + right;
}

// call async from sync
var requestTask = Task.Run(async () => await _requestService.IssueRequest(
    client => new OrgRc(client, _logger).GetAllByIdsAsync(ids),
    "Failed to get orgs by id (Id)",
    new {Id = id}
));
var result = requestTask.Result;

parallelism

// start and wait for all to complete
var left = updateLeft(generator);
var right = updateRight(generator);

await Task.When.All(left, right);
await updateTotal(generator);

// avoid serial await. use list of tasks for a loop
var tasks = new List<Task>();
foreach (var episode in eposodes)
{
    tasks.Add(downloadAsync(episode.url);
}
await Task.WhenAll(tasks);

UI Context and threadpool

// Use available thread-pool whenever possible
var file = await folder.CreateFileAsync(name, CreationCollisonOption.GenerateUniqueName)
    .AsTask().ConfigureAwait(continueOnCapturedContext: false);
    
// When touching UI element, can't use thread-pool thread
var file = await folder.CreateFileAsync(name, CreationCollisonOption.GenerateUniqueName);