c# - Cancel all async tasks -

is possible cancel async methods, without knowing running?

for example have several classes may run async tasks:

class class1 {     public async void sometask()     {         (int = 0; < 5; i++)         {             // doing job             await task.delay(2000);         }     } }  class class2 {     public async void continuouslytask()     {         (;;)         {             // doing job on background             await task.delay(1000);         }     } } 

and want turn off every async task, before logout:

class program {     static void main(string[] args)     {         var p = new program();         var c1 = new class1();         var c2 = new class2();          c1.sometask();         c2.continuouslytask();           while (console.readkey().key != consolekey.enter) { }          p.logout();     }      private void logout()     {         // cancel async tasks          // , logout work     } } 

is possible this, without saving tasks query?

this extending @frankfajardo answer provide concrete example. when pass in cancellationtoken, need monitor cancellation request outside. this:

class class1 {     public async task sometaskasync(cancellationtoken cancellationtoken)     {         (int = 0; < 5; i++)         {             if (cancellationtoken.iscancellationrequested)                 break;             // doing job             await task.delay(2000);         }     } }  class class2 {     public async task continuouslytaskasync(cancellationtoken cancellationtoken)     {         while (!cancellationtoken.iscancellationrequested)         {             // doing job on background             await task.delay(1000);         }     } } 

and when want cancel it, add cancellationtokensource.cancel() call code:

static void main(string[] args) {     var p = new program();     var c1 = new class1();     var c2 = new class2();      var cancellationtokensource = new cancellationtokensource();     var sometask = c1.sometask(cancellationtokensource.token);     var continuoustask = c2.continuouslytask(cancellationtokensource.token);       while (console.readkey().key != consolekey.enter) { }      cancellationtokensource.cancel();     task.waitall(sometask, continuoustask);      p.logout(); } 

note i'm using task.waitall because console application main can't async. otherwise, use task.whenall returns awaitable task.