#include <iostream>
#include <vector>
#include <list>
#include <stdlib.h>
#include <unistd.h>
#include <thread>
#include <cmath>
#include <mutex>
#include <sys/time.h>

using namespace std;

typedef struct __task {
  float          x;
  long           n;
} farm_task_t;

mutex locche;
list<farm_task_t *> tasks;

void worker(int no) {
  int taskno = 0;
  thread::id mythreadid = this_thread::get_id();

#ifdef DEBUG
  cout << "Worker No. " << no << " started (on thread " << mythreadid << ")" << endl;
#endif

  while(true) {
    farm_task_t t;

    locche.lock();
    if(!tasks.empty()) {
      t = *(tasks.front());
      tasks.pop_front();
      locche.unlock();
    } else {
      locche.unlock();
      break; // TODO
    }
#ifdef DEBUG
    cout << "Worker no. " << no << " got task " << t.x <<  " " << t.n << endl;
#endif
    taskno++;
    for(long i=0; i<t.n; i++) {
      t.x = sin(t.x);
    }
  }
#ifdef DEBUG
  cout << "Worker " << no << " computed " << taskno << " tasks " << endl;
#endif
  return;
}


int main(int argc, char * argv[]) {

  int opt, nw, ntasks;
  struct timeval t0, t1;

  while((opt = getopt(argc, argv, "n:m:"))!= (-1)) {
    switch(opt) {
    case 'n': {
      nw = atoi(optarg);
      break;
    }
    case 'm': {
      ntasks = atoi(optarg);
      break;
    }
    default: {
      printf("Usage is:\n%s -n pardegree -m streamlenght\n", argv[0]);
      return(0);
    }
    }
  }

  cout << "Initializing ..." << endl;

  for(int i=0; i<ntasks; i++) {
    farm_task_t * t = (farm_task_t *) calloc(1, sizeof(farm_task_t));
    t->x = (float) i;
    t->n = i*100000L;
    tasks.push_back(t);
  }
  cout << "Tasks created ..." << endl;

  vector<thread> workers;

  gettimeofday(&t0,NULL);
  for(int i=0; i<nw; i++) {
    workers.push_back(thread(bind(worker,i)));
  }
 #ifdef DEBUG
  cout << "Workers created ..." << endl;
#endif

#ifdef DEBUG
  cout << "Awaiting worker termination ..." << endl;
#endif
  for(auto &t : workers) {
    t.join();
  }
  gettimeofday(&t1,NULL);
  cout << "All workers terminated " << endl;
  cout << "Elapsed time " <<   (t1.tv_sec-t0.tv_sec)*1000.0 + ((float) (t1.tv_usec - t0.tv_usec))/1000.0 << " msecs " << endl;
  return(0);
}