public void testStopTaskWait()
{
//2020/7/17 9:47:55 before cts.cancel in thread 10 and no task // step 1
//执行cts.Cancel() // step 2
//2020/7/17 9:47:55 cancel token reg - 03 in thread 10 and no task // step 3
//2020/7/17 9:47:55 cancel token reg - 02 in thread 10 and no task // step 4
//2020/7/17 9:47:55 cancel token reg - 01 in thread 10 and no task // step 5
//Delay地方捕捉到异常 // step 6
//2020/7/17 9:47:55 after delay in thread 13 and no task // step 7
CancellationTokenSource cts = new CancellationTokenSource();
//这些注册的delegate，将在执行Cancel的时候调用到
cts.Token.Register(() => { ThreadEval_Util.TraceThreadAndTask("cancel token reg - 01"); }); // step 5
cts.Token.Register(() => { ThreadEval_Util.TraceThreadAndTask("cancel token reg - 02"); }); // step 4
cts.Token.Register(() => { ThreadEval_Util.TraceThreadAndTask("cancel token reg - 03"); }); // step 3
ThreadPool.QueueUserWorkItem(state => {
ThreadEval_Util.TraceThreadAndTask("before cts.cancel"); // step 1
Thread.Sleep(10);
cts.Cancel(); // step 2
});
//System.AggregateException : One or more errors occurred. (A task was canceled.)
// ----> System.Threading.Tasks.TaskCanceledException : A task was canceled.
Assert.Throws <AggregateException>(() => Task.Delay(100, cts.Token).Wait()); // step 6
ThreadEval_Util.TraceThreadAndTask("after delay"); // step 7
}
public void testGreetingClient()
{
//下面是这个过程的输出
//2020.07.17 10:11:55:536 testGreetingClient enter in thread 13 and no task
//2020.07.17 10:11:55:538 callGreetingClientAsync enter in thread 13 and no task
//2020.07.17 10:11:55:539 running GreetingAsync in thread 11 and task 1
//2020.07.17 10:11:55:539 running Greeting in thread 11 and task 1
//2020.07.17 10:11:55:539 testGreetingClient got Task<String> greetingResult, and next to get greetingResult.Result in thread 13 and no task
//这里有个500毫秒的gap（当时Greeting方法正在blocking wait）
//2020.07.17 10:11:56:050 callGreetingClientAsync done in thread 11 and no task
//2020.07.17 10:11:56:050 testGreetingClient done - got greetingResult.Result:Hello, HanMeiMei in thread 13 and no task
ThirdPartyAsyncSimulator greetingClient = new ThirdPartyAsyncSimulator();
//线程A - 调用者当前线程
ThreadEval_Util.TraceThreadAndTask($"{nameof(testGreetingClient)} enter");
Task <String> greetingResult = callGreetingClientAsync();
ThreadEval_Util.TraceThreadAndTask($"{nameof(testGreetingClient)} got Task<String> greetingResult, and next to get greetingResult.Result");
//线程A - 前面都很快，而执行这个获取task结果卡住了，因为结果还没有出来
String greetingResultStr = greetingResult.Result;
//线程A - 这里线程没变
ThreadEval_Util.TraceThreadAndTask($"{nameof(testGreetingClient)} done - got greetingResult.Result:{greetingResultStr}");
}
//尝试过去掉async/await，结果没啥两样。加上他们是为了让代码看起来更一致
private async Task <String> forgedTaskFromResultAsync()
{
ThreadEval_Util.TraceThreadAndTask("forgedTaskFromResultAsync - before await");
var result = await Task.FromResult(longRunTask());
ThreadEval_Util.TraceThreadAndTask("forgedTaskFromResultAsync - after await");
return(result);
}
public Task <String> GreetingAsync(String name)
{
Task <String> result = Task.Run <String>(() =>
{
ThreadEval_Util.TraceThreadAndTask($"running {nameof(GreetingAsync)}");
return(Greeting(name));
});
return(result);
}
/**
*
* 这里给出了1个使用httpclient async方法的例子（其实也没看出来节省时间！因为最外部调用方法还是要等待）
* 注释掉了[Test]是因为其有外部依赖（baidu.com). 这个调用过程用上面的Greeting完全是一致的
*
*/
//[Test]
public void testHttpClient()
{
//线程A
ThreadEval_Util.TraceThreadAndTask("{nameof(testHttpClient)} enter");
Task <int> lengthTask = GetPageLengthAsync("http://www.baidu.com");
//在async方法运行的时候，当前task已经返回到这里了，但是如果这里获取结果的话，则继续等待直到async方法执行完毕
//也就是说，从这儿的角度，其并没有加快什么
//除非当前这里的业务逻辑不在乎task执行结果（我是说这一行不在乎执行结果，执行结果可以在GetPageLengthAsync里的线程B中做某种处理）································································································································································································································································································································································································································································································································································································································································································································································································································
Console.WriteLine(lengthTask.Result);
//线程A - 这里线程没变
ThreadEval_Util.TraceThreadAndTask("{nameof(testHttpClient)} done");
}
public async Task testTaskAsyncDelay()
{
//2020.07.17 10:09:59:294 before delay in thread 13 and no task - step 1 - 调用者线程
//调用者碰到await直接返回，继续执行其他工作(这里的调用者实际上为NUnit测试框架） - step 2
//2020.07.17 10:09:59:394 after delay in thread 9 and no task - step 3 - 100毫秒之后，新线程继续执行
Int32 delayInterval = 100;
//线程A
ThreadEval_Util.TraceThreadAndTask("before delay"); //step 1
//线程A执行到await之后，立马返回
await Task.Delay(delayInterval); //step 2
//过delayInterval毫秒之后，线程B继续执行下面逻辑
//线程B
ThreadEval_Util.TraceThreadAndTask("after delay"); //step 3
}
public void testTaskFromResult()
{
//全部都是在同步调用，只不过可以融入到async调用的moshi
//2020.07.17 22:11:27:820 forgedTaskFromResultAsync - before await in thread 13 and no task
//2020.07.17 22:11:27:822 longRunTask in thread 13 and no task
//2020.07.17 22:11:30:825 forgedTaskFromResultAsync - after await in thread 13 and no task
//2020.07.17 22:11:30:825 task got in thread 13 and no task
//2020.07.17 22:11:30:825 task result got in thread 13 and no task
var task = forgedTaskFromResultAsync();
ThreadEval_Util.TraceThreadAndTask("task got");
var result = task.Result;
ThreadEval_Util.TraceThreadAndTask("task result got");
}
static async Task <int> GetPageLengthAsync(string url)
{
using (HttpClient client = new HttpClient()) {
//线程A
ThreadEval_Util.TraceThreadAndTask("{nameof(GetPageLengthAsync)} enter");
Task <String> fetchTextTask = client.GetStringAsync(url);
//代码执行到这里方法就返回了。这个耗时的client.GetStringAsync(url)将在
//<=====这个await的magic之处在于前后的线程变了
int length = (await fetchTextTask).Length;
//线程B 《=== 不再是线程A了！！！！
ThreadEval_Util.TraceThreadAndTask("{nameof(GetPageLengthAsync)} done");
//注意，函数返回类型为Task<int>, 但是我们这里要返回int
return(length);
}
}
public async Task <String> callGreetingClientAsync()
{
ThirdPartyAsyncSimulator greetingClient = new ThirdPartyAsyncSimulator();
//线程A - 就是调用者所在的线程
ThreadEval_Util.TraceThreadAndTask($"{nameof(callGreetingClientAsync)} enter");
Task <String> greetingResult = greetingClient.GreetingAsync("HanMeiMei");
//一旦开始await，这个方法就返回了。调用方法立马得到了Task<String>的结果
//String greetingResultStr = await greetingResult;
//这里使用await greetingResult与 await greetingResult.ConfigureAwait(false)是一样的
//note：但是如果是UI程序，或者asp.net则不一样
//使用ConfigureAwait(false)的目的是让醒来后的线程可以是随意一个线程池中的线程
//见本类开头更多总结
String greetingResultStr = await greetingResult.ConfigureAwait(false);
//线程B - await之后，task执行之后，处理执行结果是其他线程（不再保证是进入是的线程A）
ThreadEval_Util.TraceThreadAndTask($"{nameof(callGreetingClientAsync)} done");
return(greetingResultStr);
}
public void testResetEvent()
{
//ThreadEval_QueueUserWorkItem::testBasicTaskExecution中，使用了ManualResetEvent
//注意：如果在Wait之前就发送了信号by Set（），也没关系
//下面就是证明这个的， WaitOne执行的时候，Set已经执行完了。WaitOne还是顺利的继续执行
//false：not signaled, 就是需要等待一个新信号才能执行的意思，就是执行WaitOne的时候会block的意思
//true：signaled, 直接WaitOne就能返回了
ManualResetEvent mre = new ManualResetEvent(false);
ThreadPool.QueueUserWorkItem(state => {
Thread.Sleep(5);
ThreadEval_Util.TraceThreadAndTask("002 before set");
mre.Set();
});
Thread.Sleep(1000);
ThreadEval_Util.TraceThreadAndTask("002 before wait");
for (int i = 0; i < 5; i++)
{
//因为没有执行Reset，其一直是signaled状态，所以WaitOne一直可以返回
mre.WaitOne(); //很可惜没有等待时间超时设置
}
ThreadEval_Util.TraceThreadAndTask("003 got signal");
}
private String longRunTask()
{
ThreadEval_Util.TraceThreadAndTask("longRunTask");
Task.Delay(3000).Wait();
return("abc");
}
public void testParallelFor_3delegates()
{
var nums = Enumerable.Range(1, 99);
//ForEach<TSource, TLocal>
//- TSource: 顾名思义，就是输入数据的类型
//- TLocal是第一个LocalInit方法返回值。该值在整个上下文中使用
// - 之后，其被传入body方法中（最后的那个参数）
// - 特别注意：body中调用的方法也要返回该类型
// - 最后LocalFinally方法的输入参数类型就是它，值将一路传递下来
//
//- 特别注意： 该方法还有更多参数（譬如增加option），参考文档
//
//, ,
//如何Cancel，看这连接https://docs.microsoft.com/en-us/dotnet/standard/parallel-programming/how-to-cancel-a-parallel-for-or-foreach-loop
ParallelOptions options = new ParallelOptions();
CancellationTokenSource cts = new CancellationTokenSource();
options.CancellationToken = cts.Token;
//cts.Cancel();外部线程执行这个就cancel了
ParallelLoopResult result = Parallel.ForEach <Int32, Int32>(
//IEnumerable<TSource> source
nums,
options,
//特别注意：每个线程运行一次
//Func<TLocal> localInit - 输入值：empty，返回值TLocal的方法
() =>
{
ThreadEval_Util.TraceThreadAndTask("localInit");
return(0);
},
//Func<TSource, ParallelLoopState, long, TLocal, TLocal> body - 输入值：TSource, ParallelLoopState, long, TLocal，返回值：TLocal
//最后一个输入参数：taskLocalTotal 是从localInit中传过来的，可以在body方法中更新它
(i, loopState, index, taskLocalTotal) => {
//注意：stop/break都不会从当前方法返回，当前方法还会继续执行完
//但是新的iteration大概率不会继续开始，这是有Parallel框架来判断的
//Stop
ThreadEval_Util.TraceThreadAndTask($"004-body:{i}-{index} before stop");
//应该用if(options.CancellationToken.IsCancellationRequested)，外部调用
//可以使用token.ThrowIfCancellationRequested()， 不过Parallel外部要捕捉异常
//参考 https://stackoverflow.com/questions/8818203/what-is-difference-between-loopstate-break-loopstate-stop-and-cancellationt
//这里为了测试，直接比较i>10
if (i > 10)
{
loopState.Stop();
//loopState.Break();
ThreadEval_Util.TraceThreadAndTask($"003-body:{i}-{index} stop here");
}
ThreadEval_Util.TraceThreadAndTask($"003-body:{i}-{index} after stop");
Thread.Sleep(100);
//loopState.Stop();
return(DoWork(i));
},
//特别注意：每个线程运行一次
//Action<TLocal> localFinally - 输入值：TLocal（即talksLocalTotal）， 返回值：empty
//talksLocalTotal是从body中传过来的
talksLocalTotal =>
{
ThreadEval_Util.TraceThreadAndTask("localFinally");
}
);
Console.WriteLine($"result.LowestBreakIteration:{result.LowestBreakIteration.ToString()}");
}
public void testParallelForOfAsync()
{
//2020.07.17 12:12:48:143 S 3 in thread 14 and task 4
//2020.07.17 12:12:48:143 S 1 in thread 11 and task 2
//2020.07.17 12:12:48:143 S 4 in thread 15 and task 5
//2020.07.17 12:12:48:143 S 2 in thread 6 and task 3
//2020.07.17 12:12:48:143 S 0 in thread 13 and task 1
//2020.07.17 12:12:48:144 S 6 in thread 18 and task 7
//2020.07.17 12:12:48:143 S 5 in thread 16 and task 6
//2020.07.17 12:12:48:144 S 7 in thread 17 and task 8
//2020.07.17 12:12:49:029 E 7 in thread 17 and task 8
//2020.07.17 12:12:49:029 E 5 in thread 16 and task 6
//2020.07.17 12:12:49:029 E 6 in thread 18 and task 7
//2020.07.17 12:12:49:029 E 0 in thread 13 and task 1
//2020.07.17 12:12:49:029 S 8 in thread 19 and task 9
//2020.07.17 12:12:49:029 E 4 in thread 15 and task 5
//2020.07.17 12:12:49:029 S 9 in thread 13 and task 1
//2020.07.17 12:12:49:029 E 1 in thread 11 and task 2
//2020.07.17 12:12:49:029 E 3 in thread 14 and task 4
//2020.07.17 12:12:49:029 E 2 in thread 6 and task 3
//2020.07.17 12:12:49:234 E 9 in thread 13 and task 1
//2020.07.17 12:12:49:234 E 8 in thread 19 and task 9
//2020.07.17 12:12:49:234 Completed - WITHOUT async/with - True in thread 13 and no task
//这是没有async/await的情况，用于对比
//可以看到S/E所使用的线程是一致是一样的；还可以看到这个Delay的时间不是很准确，我要delay200毫秒，而这里显示达到了900毫秒左右。
ParallelLoopResult result1 = Parallel.For(0, 10, i =>
{
ThreadEval_Util.TraceThreadAndTask($"S {i}");
Task.Delay(200).Wait();
ThreadEval_Util.TraceThreadAndTask($"E {i}");
});
ThreadEval_Util.TraceThreadAndTask($"Completed - WITHOUT async/with - {result1.IsCompleted}");
//2020.07.17 12:12:49:236 S 0 in thread 13 and task 10
//2020.07.17 12:12:49:236 S 6 in thread 14 and task 11
//2020.07.17 12:12:49:236 S 7 in thread 11 and task 12
//2020.07.17 12:12:49:236 S 2 in thread 19 and task 13
//2020.07.17 12:12:49:236 S 8 in thread 18 and task 14
//2020.07.17 12:12:49:236 S 1 in thread 17 and task 15
//2020.07.17 12:12:49:236 S 3 in thread 16 and task 16
//2020.07.17 12:12:49:236 S 4 in thread 15 and task 17
//2020.07.17 12:12:49:236 S 5 in thread 6 and task 18
//2020.07.17 12:12:49:238 S 9 in thread 13 and task 10
//2020.07.17 12:12:49:239 Completed - WITH async/with - True in thread 13 and no task
//2020.07.17 12:12:49:429 E 9 in thread 6 and no task
//2020.07.17 12:12:49:429 E 3 in thread 11 and no task
//2020.07.17 12:12:49:429 E 8 in thread 16 and no task
//2020.07.17 12:12:49:429 E 1 in thread 18 and no task
//2020.07.17 12:12:49:429 E 4 in thread 17 and no task
//2020.07.17 12:12:49:429 E 7 in thread 14 and no task
//2020.07.17 12:12:49:429 E 5 in thread 19 and no task
//2020.07.17 12:12:49:429 E 2 in thread 15 and no task
//2020.07.17 12:12:49:429 E 0 in thread 11 and no task
//2020.07.17 12:12:49:429 E 6 in thread 19 and no task
//1. 这里可以看到，S/E所对应的线程是不同的
//2. Parallel.For方法直接返回了（没有等Delay执行完成 - Completed直接打印了）
// 过了一会儿，await完成后其他线程把await后的结果执行一遍
ParallelLoopResult result2 = Parallel.For(0, 10, async i =>
{
ThreadEval_Util.TraceThreadAndTask($"S {i}");
await Task.Delay(200);
ThreadEval_Util.TraceThreadAndTask($"E {i}");
});
ThreadEval_Util.TraceThreadAndTask($"Completed - WITH async/with - {result1.IsCompleted}");
//下面这个Sleep是有必要的，因为使用了async之后，Parallel调用直接返回（碰到await就返回了），不等待Delay。
//如果不加这个Sleep，测试case就直接完成了，则后续的ThreadEval_Util.TraceThreadAndTask($"E {i}");无法打印了。
Thread.Sleep(250);
}
private String Greeting(String name)
{
ThreadEval_Util.TraceThreadAndTask($"running {nameof(Greeting)}");
Task.Delay(500).Wait();
return($"Hello, {name}");
}