#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
#include <math.h>
#include <time.h>

pthread_mutex_t mutex;

typedef struct __task {
  long n;
  float x;
  struct __task * next;
} TASK;

TASK * tasks = NULL;

typedef unsigned long long ticks;

static __inline__ ticks getticks(void)
{
  unsigned a, d;
  asm volatile("rdtsc" : "=a" (a), "=d" (d));
  return ((ticks)a) | (((ticks)d) << 32);
}



void * worker(void * x) {
  int wno = *((int *) x);
  int * taskno = (int *) calloc(1, sizeof(int));

  *taskno = 0;

#ifdef DEBUG
  printf("Worker no %d created\n", wno);
#endif

  while(1==1) {
    // get a task from the list
    pthread_mutex_lock(&mutex);
    TASK * t = tasks;
    if(tasks!=NULL) {
      tasks = tasks->next;
    }
    pthread_mutex_unlock(&mutex);
    // process
    if(t == NULL)
      break; // nothing else to process
#ifdef DEBUG
    printf("Thread %ld processing task <%ld,%f>\n",pthread_self(), t->n, t->x);
#endif
    {
      long l;
      for(l=0; l<t->n; l++)
        t->x = sin(t->x);
    }
    // write results
#ifdef DEBUG
    printf("Thread %ld computed %f\n",pthread_self(),t->x);
#endif
    (*taskno)++;
  }
  return ((void *) taskno);
}

int main(int argc, char * argv[]) {
  int opt, nw, m, i ;
  float ta,tb,elapsed;
  pthread_t *w;
  struct timeval t0, t1;
  clock_t before, after;
  struct timespec c0,c1,p0,p1;
  ticks tck0, tck1;

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

#ifdef DEBUG
  printf("%d workers and %d tasks\n", nw, m);
#endif
  w = (pthread_t *) calloc(nw, sizeof(pthread_t));

  if((pthread_mutex_init(&mutex,NULL)!=0)) {
    printf("Failed to initialize the mutex\n");
    return(-1);
  }

  for(i=0; i<m; i++) {
    TASK * t = (TASK *) calloc(1, sizeof(TASK));
    t->x = (float)i ;
    t->n = (long) i*(100000L);
    pthread_mutex_lock(&mutex);   // may be in principle concurrent with task consuming
    t->next = tasks;
    tasks = t;
    pthread_mutex_unlock(&mutex);
  }

  before = clock();
  clock_gettime(CLOCK_THREAD_CPUTIME_ID,&c0);
  clock_gettime(CLOCK_PROCESS_CPUTIME_ID,&p0);
  gettimeofday(&t0,NULL);
  tck0 = getticks();
#ifdef DEBUG
  printf("Start %ld %ld \n", t0.tv_sec, t0.tv_usec);
#endif
  for(i=0; i<nw; i++) {
    // create the workers: they'll start working immediately
    if(pthread_create(&w[i],NULL, worker, &i)!=0) {
      printf("Error creating workers\n");
      return(-1);
    }
  }

  // workers running: wait termination
  for(i=0; i<nw; i++) {
    void * retcode;
    pthread_join(w[i],&retcode);
    printf("Worker %d terminated computing %d tasks\n",
           i, *((int *) retcode));
    fflush(stdout);
  }
  gettimeofday(&t1,NULL);
  clock_gettime(CLOCK_THREAD_CPUTIME_ID,&c1);
  clock_gettime(CLOCK_PROCESS_CPUTIME_ID,&p1);
  after = clock();
  tck1 = getticks();
#ifdef DEBUG
  printf("Start %ld %ld \n", t1.tv_sec, t1.tv_usec);
#endif
  printf("Elapsed %f msecs\n", (t1.tv_sec-t0.tv_sec)*1000.0 + ((float) (t1.tv_usec - t0.tv_usec))/1000.0);
  printf("Clock cycles %ld (%f msecs)\n", after-before, ((after-before)/ CLOCKS_PER_SEC));
  {
    float tproc =  ((float) (p1.tv_sec - p0.tv_sec))*1000.0 + ((float) (p1.tv_nsec-p0.tv_nsec))/1000000.0;
    float tthread = ((float) (c1.tv_sec - c0.tv_sec))*1000.0 + ((float) (c1.tv_nsec-c0.tv_nsec))/1000000.0;
    printf("clock_gettime (per process) %f msecs\n", tproc);
    printf("clock_gettime (per thread) %f msecs\n", tthread);
    printf("clock_gettime: average per worker %f\n", (tproc - tthread)/nw);
  }
  printf("Ticks %lld\n", tck1-tck0);

  printf("Workers terminated\n");
  return(0);
}