trouble with boost error lock - c++

Question

I can't figure out where is the problem with this simple code, I think that here is the trouble with output to Console maybe deadlock or something, can somebody, please help.
#include <iostream>
#include <string>
#include <sstream>
#include <boost/thread.hpp>
using namespace std;
struct IntegrateTask
{
int id;
double from, to, step, result;
IntegrateTask(int id, double from, double to, double step)
{
this -> id;
this -> from = from;
this -> to = to;
this -> step = step;
}
~IntegrateTask()
{}
};
vector<IntegrateTask> * tasks = new vector<IntegrateTask>();
boost::mutex mutlist;
boost::mutex iomutex;
boost::condition_variable condtask;
bool isInterrupted = false;
double foo(double x)
{
return x * x;
}
void integrate(IntegrateTask * task)
{
double result = 0;
double step = task -> step;
for(double i = task -> from ; i != task -> to; i =+ step)
{
result += foo(i) * step;
}
task -> result = result;
}
void integrateThread()
{
boost::thread::id id = boost::this_thread::get_id();
try
{
{
boost::mutex::scoped_lock iolock(iomutex);
cout << "Thread #" << id << " is working!" << endl;
}
while(!isInterrupted)
{
IntegrateTask * currtask = NULL;
{
boost::mutex::scoped_lock lock(mutlist);
while(!isInterrupted && tasks -> empty())
{
condtask.wait(lock);
}
if (!tasks -> empty())
{
currtask = &tasks->back();
tasks->pop_back();
}
}
if (currtask != NULL)
{
integrate(currtask);
boost::mutex::scoped_lock iolock(iomutex);
cout << "Task #" << (currtask->id) << "; result = " << (currtask->result) << endl;
}
}
boost::mutex::scoped_lock iolock(iomutex);
cout << "Thread # " << id << " stoped working normal!" << endl;
}
catch(boost::thread_interrupted)
{
boost::mutex::scoped_lock ioLock(iomutex);
cout << "Thread # " << id << " stoped working by interruption!" << endl;
}
catch(exception & e)
{
boost::mutex::scoped_lock iolock(iomutex);
cout << "Error: " << e.what() << endl;
}
}
int main()
{
cout << "Function for integration: f(x)=x*x" << endl;
cout << "For stopping program press EXIT" << endl;
int thcount = 6;// or boost::thread::hardware_concurrency()
boost::thread_group thgroup;
for (int i = 1; i <= thcount; i++){
thgroup.create_thread(&integrateThread);
}
int id = 0;
while (true)
{
string line;
{
boost::mutex::scoped_lock iolock(iomutex);
cout << "Task #" << ++id << "; left bound, right bound and step: ";
getline(cin, line);
}
if (line.find("e") != string::npos)
{
isInterrupted = true;
condtask.notify_all();
thgroup.interrupt_all();
thgroup.join_all();
return 0;
}
double from, to, step;
istringstream input(line);
input >> from >> to >> step;
IntegrateTask * task = new IntegrateTask(id, from, to, step);
{
boost::mutex::scoped_lock lock(mutlist);
tasks->push_back(*task);
}
condtask.notify_one();
}
}

Answer 1

I haven't tried to follow the logic of what you're aiming to achieve here, but there are 2 issues (at least):
You're not using id in IntegrateTask's constructor. You should generally favour initialisation lists over assignments in constructor bodies, and using class member variable names in function signatures is a recipe for disaster too, so I'd change your constructor to:
IntegrateTask(int id_init, double from_init, double to_init, double step_init)
: from(from_init), to(to_init), step(step_init), id(id_init) {}
The probable cause of the hanging is your use of != in the for loop in integrate. If you change that to < your program shouldn't hang, but I'm not sure if this breaks your program's logic.