【C#】52. 使用Flatten方法处理并行任务抛出的异常

async static Task<string> GetInfoAsync(string name, int seconds)
{
await Task.Delay(TimeSpan.FromSeconds(seconds));
throw new Exception(string.Format("Boom from {0}!", name));
}

async static Task AsynchronousProcessing()
{
Console.WriteLine("1. Single exception");
try
{
string result = await GetInfoAsync("Task 1", 2);
Console.WriteLine(result);
}
catch (Exception ex)
{
Console.WriteLine("Exception details: {0}", ex);
}
}

Console.WriteLine("2. Multiple exceptions");
Task<string> t1 = GetInfoAsync("Task 1", 3);
Task<string> t2 = GetInfoAsync("Task 2", 2);
try
{
string[] results = await Task.WhenAll(t1, t2);
Console.WriteLine(results.Length);
}
catch (Exception ex)
{
Console.WriteLine("Exception details: {0}", ex);
}

Console.WriteLine("2. Multiple exceptions with AggregateException");
var t1 = GetInfoAsync("Task 1", 3);
var t2 = GetInfoAsync("Task 2", 2);
Task<string[]> t3 = Task.WhenAll(t1, t2);
try
{
string[] results = await t3;
Console.WriteLine(results.Length);
}
catch
{
var ae = t3.Exception.Flatten(); //这句话是关键！
var exceptions = ae.InnerExceptions;
Console.WriteLine("Exceptions caught: {0}", exceptions.Count);
foreach (var e in exceptions)
{
Console.WriteLine("Exception details: {0}", e);
Console.WriteLine();
}
}