Passing Arguments of Various Types to TThread

ROOT
#1

Hi All,

I’ve created a function which takes arguments of type TString and Double_t which I would like to utilize in TThreads. I’ve been able to get the TThread examples from the ROOT tutorials page to work, but have not been able to figure out how to pass multiple variables and variables of different types to TThread. I’ve created this simple script to show proof of concept…any thoughts you can provide are greatly appreciated…thanks.

void *myFunction(TString Particle, Double_t Energy){
cout <<This thread is: " <<Particle <<" " <<Energy <<endl;
return 0;
}

void contrulFun(){
TThread *pionThread = new TThread(“pionThread”,myFunction,[NOT SURE HOW TO STRUCTURE ARGS]);
TThread *protonThread = new TThread(“pionThread”,myFunction,[NOT SURE HOW TO STRUCTURE ARGS]);

    pionThread->Run();
    protonThread->Run();

    pionThread->Join();
    protonThread->Join();

}

#2

The function should take a void * as an argument. A void * may be cast between any type of pointer. The easiest way to do what you want is probably something like this (warning, I didn’t test):


struct myFuncArgs
{
   TString particle; 
   Double_t energy; 
};

void * myFunction(void * a)
{
  myFuncArgs args = (myFuncArgs*) a; 
  cout << This thread is: " << args.particle << " " << args.energy << endl; 
  return 0; 
}


void controlFun()
{
 myFuncArgs pionArgs; 
 pionArgs.energy = 140; 
 pionArgs.earticle = "pi+";

 TThread * pionThread = new TThread("pionThread", myFunction, (void*) &pionArgs);  

 myFuncArgs protonArgs; 
 protonArgs.energy = 938; 
 protonArgs.earticle = "p";

 TThread * protonThread = new TThread("protonThread", myFunction, (void*) &protonArgs);  

 pionThread->Run(); 
 protonThread->Run(); 

 pionThread->Join(); 
 protonThread->Join();

}