private static Task WriteWebRequestSizeAsync(string url)
{
StreamReader reader = null;
WebRequest webRequest = WebRequest.Create(url);
Task <WebResponse> task = webRequest.GetResponseAsync();
task.ContinueWith(antecedent =>
{
WebResponse response = antecedent.Result;
reader = new StreamReader(response.GetResponseStream());
return(reader.ReadToEndAsync());
})
.Unwrap()
.ContinueWith(antecedent =>
{
if (reader != null)
{
reader.Dispose();
}
string text = antecedent.Result;
Console.WriteLine(SyncTest.FormatBytes(text.Length));
});
return(task);
}
private static async Task WriteWebRequestSizeAsync(string url)
{
try
{
WebRequest webRequest = WebRequest.Create(url);
ConsoleTaskTest7Info($"in WriteWebRequestSizeAsync before GetResponseAsync {Thread.CurrentThread.ManagedThreadId}");
WebResponse response = await webRequest.GetResponseAsync();
ConsoleTaskTest7Info("download finished.");
ConsoleTaskTest7Info($"in WriteWebRequestSizeAsync after GetResponseAsync {Thread.CurrentThread.ManagedThreadId}");
using (StreamReader reader = new StreamReader(
response.GetResponseStream()))
{
ConsoleTaskTest7Info($"Now, Thread.CurrentThread.ManagedThreadId is {Thread.CurrentThread.ManagedThreadId}");
ConsoleTaskTest7Info("reading in using, and delay 5s");
ConsoleTaskTest7Info($"start time is {DateTime.Now.ToString()}");
await Task.Delay(5000);
ConsoleTaskTest7Info($"After await Task.Delay(5000), Thread.CurrentThread.ManagedThreadId is {Thread.CurrentThread.ManagedThreadId}");
ConsoleTaskTest7Info($"end time is {DateTime.Now.ToString()}");
string text = await reader.ReadToEndAsync();
ConsoleTaskTest7Info($"After await reader.ReadToEndAsync(), Thread.CurrentThread.ManagedThreadId is {Thread.CurrentThread.ManagedThreadId}");
ConsoleTaskTest7Info(SyncTest.FormatBytes(text.Length));
}
}
catch (WebException)
{
throw new WebException();
}
catch (IOException)
{
throw new IOException();
}
catch (NotSupportedException)
{
throw new NotSupportedException();
}
}
/// <summary>
/// 当运行Task task = WriteWebRequestSizeAsync(url);时,在await之前,没有返回task
/// 知道遇到了第一个await,然后task.wait生效,开始输出点
/// 运行完毕第一个task后,会继续运行,
/// 如果遇到下个await,仍旧会返回task
/// 直至代码段结束
/// 可以说,task.Wait(100)会仅等待await的结果.
/// 注意，无论将await放到循环中，还是单独地写，它们都会连续地、一个接一个地执行，
/// 而且顺序和从调用线程中调用的顺序一样。
/// 底层实现是用语义上等价于Task.ContinueWith()的方式把它们串接到一起，
/// 只是await操作符之间的代码全都在调用者的同步上下文中执行。
/// </summary>
public static void TestStart()
{
string url = "https://github.com/Microsoft/TypeScript/issues/315";
Task task = WriteWebRequestSizeAsync(url);
while (!task.Wait(100))
{
Console.Write(".");
}
// Console.WriteLine("writeWebRequestSizeWithLambdaAsync start");
Func <string, Task> writeWebRequestSizeWithLambdaAsync =
async(string webRequestUrl) =>
{
WebRequest webRequest = WebRequest.Create(webRequestUrl);
ConsoleTaskTest7Info($"in writeWebRequestSizeWithLambdaAsync before GetResponseAsync {Thread.CurrentThread.ManagedThreadId}");
WebResponse response = await webRequest.GetResponseAsync();
ConsoleTaskTest7Info($"in writeWebRequestSizeWithLambdaAsync after GetResponseAsync {Thread.CurrentThread.ManagedThreadId}");
using (StreamReader reader = new StreamReader(
response.GetResponseStream()
))
{
ConsoleTaskTest7Info($"Thread.CurrentThread.ManagedThreadId in Func<string, Task> is {Thread.CurrentThread.ManagedThreadId}");
string text = await reader.ReadToEndAsync();
ConsoleTaskTest7Info($"size is {SyncTest.FormatBytes(text.Length)}");
}
};
// Task taskWithLambda = writeWebRequestSizeWithLambdaAsync(url);
// while (!taskWithLambda.Wait(100))
// {
// Console.Write(".");
// }
}