. NET Async await

usingSystem;usingSystem.Net.Http;usingSystem.Threading;usingSystem.Threading.Tasks;namespacecookbook{classProgram {Static voidMain (string[] args) {            //Class1 class1 = new Class1 (); //Console.WriteLine ("Main thread start"); //Class1.            Dosomethingasync (); //Console.WriteLine ("Main thread End"); //Class2 class2 = new Class2 (); //Console.WriteLine ("Main thread start"); //Class2.            Dosomethingasync (); //Console.WriteLine ("Main thread End"); //String info = Class3.geturlstr ("http://www.baidu.com"); //Console.WriteLine (info);Console.WriteLine ("1 Main thread start: {0}", Thread.CurrentThread.ManagedThreadId); Program P=NewProgram (); stringURL ="http://www.baidu.com"; intTimeout =1;            P.dosomethingasync (URL, timeout);            P.dosomething (); Console.WriteLine ("6 Main thread end: {0}", Thread.CurrentThread.ManagedThreadId);        Console.readkey (); }         Public AsyncTask Dosomethingasync (stringUrlintTimeout) {Console.WriteLine ("2 Child thread start: {0}", Thread.CurrentThread.ManagedThreadId); Try            {                varresult =awaitdownloadstringwithretries (URL, timeout); Console.WriteLine ("{0}", result); }            Catch(Exception ex) {Console.WriteLine ("7 error: {1},{0}", Thread.CurrentThread.ManagedThreadId, ex.            Message); } Console.WriteLine ("4 Child thread end: {0}", Thread.CurrentThread.ManagedThreadId); }        Private voiddosomething () {Console.WriteLine ("3 main thread start: {0}", Thread.CurrentThread.ManagedThreadId);  for(intj =0; J! = +; J + +)            {                intresult =0;  for(inti =0; I! =10000000; i++) {result*=i; }} Console.WriteLine ("5 Main thread start: {0}", Thread.CurrentThread.ManagedThreadId); }        /// <summary>        ///get URL source code, error retry/// </summary>        /// <param name= "url" ></param>        /// <param name= "Timeout" ></param>        /// <returns></returns>        Private Asynctask<string> Downloadstringwithretries (stringUrlintTimeout) {            varNextdelay = Timespan.fromseconds (1);  for(inti =0; I! =3; ++i) {Try                {                    return awaitdownloadstringwithtimeout (URL, timeout); }                Catch                {                }                awaitTask.delay (Nextdelay); Nextdelay= Nextdelay +Nextdelay; }            return awaitdownloadstringwithtimeout (URL, timeout); }        /// <summary>        ///get URL source code, time out direct error/// </summary>        /// <param name= "url" ></param>        /// <param name= "Timeout" ></param>        /// <returns></returns>        Private Asynctask<string> Downloadstringwithtimeout (stringUrlintTimeout) {            using(varClient =NewHttpClient ()) {                varDownloadtask =client.                Getstringasync (URL); varTimeouttask =Task.delay (timeout); varCompletedtask =awaitTask.whenany (Downloadtask, Timeouttask); if(Completedtask = =timeouttask) {                    Throw NewException ("Processing Timeout"); }                return awaitDownloadtask; }        }    }}

. NET Async await