c# - sequential execution inside a parallel for each loop -

my requirement thing this. have few independent jobs , few sequential jobs abide contract. in client app, inside parallel loop need make sure independent tasks executed in order if sequential should 1 after another. below code. thanks,

 using system;  using system.collections.generic;  using system.linq;  using system.text;  using system.reflection;  using system.threading.tasks;  namespace sample { class program {     static void main(string[] args)     {         program p = new program();          list<icontract> list = p.run();          parallel.foreach(list, t=> t.execute());     }      list<icontract> run()     {           list<icontract> list = new list<icontract>();      type[] typesinthisassembly = assembly.getexecutingassembly().gettypes();       array.foreach(         typesinthisassembly,         type =>           {             // if type of interface not ichartview, continue loop             if (type.getinterface(typeof(icontract).tostring()) != null)             {               var contractobj = activator.createinstance(type, new object[] { }) icontract;                list.add(contractobj);              }            });          return list;      }     }   public interface icontract {     void execute(); }  public class xmljob : icontract {     public void execute()     {         console.writeline("step1: getting data xml");      }  } public class dumptodbjob : icontract {     public void execute()     {         console.writeline("step2: dumping data whihc came in xml");      }  } public class independentjob1 : icontract {     public void execute()     {         console.writeline("this independent job");      }  } public class independentjob2 : icontract {     public void execute()     {         console.writeline("this independent job ");      }  } }  

desire out put

this independent job step1: getting data xml step2: dumping data whihc came in xml independent job press key continue . . .

can this

      program p = new program();          list<icontract> list = p.run();           icontract xj = list.find(i => i.gettype().tostring() == typeof(xmljob).tostring());          icontract dj = list.find(i => i.gettype().tostring() == typeof(dumptodbjob).tostring());          list.remove(xj);          list.remove(dj);           parallel.foreach(list, l => l.execute());         list<task> tasks = new list<task>();           task t1 = task.factory.startnew(xj.execute);          task t2 = t1.continuewith((antecedent)=>dj.execute());          tasks.add(t1);         tasks.add(t2);         task.waitall(tasks.toarray()); 

for of sequential tasks should have single icontract. execute method of contract should call 2, 3, etc. methods need run sequentially. if have group of 2 tasks run sequentially icontract. should not have more 1 icontracts defined group of tasks should run in sequence. if don't want way you'll need re-design entire framework introduce dependencies or more involved.