C++0x, thread, promise and future

[Claudio La Rosa <clros@xxxxxxxxxx>]

Hello! 

I am making a simple template class for communication with two thread in
C++0x, using the promise and future. 
My class make a channel to communicate thread with the main program and
another channel to allow the child thread to initiate communication with the
parent thread (or main program). 

This is the code: 


#include <iostream> 
#include <future> 
#include <thread> 

using namespace std; 

template<typename T = std::string,typename T1 = std::string> 
class ThreadChannel 
{ 
    private: 
     std::promise<T> ch1_Promise; 
     std::future<T>  ch1_Future; 

     std::promise<T1> ch2_Promise; 
     std::future<T1>  ch2_Future; 

    public: 
        ThreadChannel(); 
        virtual ~ThreadChannel(); 

         T1 recvFromFather(void); 
         void sendToChild(T1); 
         //canale 1 
         void sendToFather(T); 
         T recvFromChild(void); 

}; 


// 
template<typename T,typename T1> 
ThreadChannel<T,T1>::ThreadChannel() 
{ 
 ch1_Future = ch1_Promise.get_future(); 
 ch2_Future = ch2_Promise.get_future(); 
} 

template<typename T,typename T1> 
ThreadChannel<T,T1>::~ThreadChannel() 
{ 
  //cout<<"Sono nel distruttore!!"<<endl; 
} 

template<typename T,typename T1> 
T ThreadChannel<T,T1>::recvFromChild() 
{ 
  return ch1_Future.get(); 
} 

template<typename T,typename T1> 
void ThreadChannel<T,T1>::sendToFather(T data) 
{ 
  return ch1_Promise.set_value(data); 
} 

template<typename T,typename T1> 
void ThreadChannel<T,T1>::sendToChild(T1 data) 
{ 
  return ch2_Promise.set_value(data); 
} 

template<typename T,typename T1> 
T1 ThreadChannel<T,T1>::recvFromFather() 
{ 
  return ch2_Future.get(); 
} 


void myAsyncFun(ThreadChannel<int,int>* ch) 
{ 
    while(1) 
    { 
     int r = ch->recvFromFather(); 
     ch->sendToFather(++r); 
    } 
} 

int main() 
{ 
    ThreadChannel<int,int>* myChannel=new ThreadChannel<int,int>(); 
    // thread 
    std::thread* t = new std::thread(myAsyncFun,myChannel); 
    int myVar = 33; 
    myChannel->sendToChild(myVar); 
    int resp = myChannel->recvFromChild(); 
    cout<<"Response from thread: "<<resp<<endl; 

  
    t->join(); 
    delete myChannel; 

    return 0; 
} 

The first time the while loop executes (in myAsyncFun), it works well. 
but the second time, when for the second time the statement is executed: 

int r = ch-> recvFromFather (); 

I have a segmentation fault. 

Why?

(I use GCC 4.5.2 on Linux Ubuntu and libpthread 2.13)
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