/***************************************************************************
 *   Copyright (C) 2005 by Jeff Ferr                                       *
 *   root@sat                                                              *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include "jthreadpool.h"
#include "jrunnable.h"

#include <iostream>

#include <stdio.h>
#include <math.h>
#include <time.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdlib.h>

#define MAX_THREAD	10000

typedef struct {
	int id;
	int noproc;
	int dim;
} parm;

typedef struct {
	int cur_count;
	pthread_mutex_t barrier_mutex;
	pthread_cond_t barrier_cond;
} barrier_t;

barrier_t barrier1;

double *finals;
int rootn;

void barrier_init(barrier_t * mybarrier)
{
	/* must run before spawning the thread */
	pthread_mutexattr_t attr;

	pthread_mutexattr_setprotocol(&attr, PTHREAD_PRIO_INHERIT);
	pthread_mutexattr_setprioceiling(&attr, 0); 

	pthread_mutex_init(&(mybarrier->barrier_mutex), &attr);
	pthread_cond_init(&(mybarrier->barrier_cond), NULL);
	mybarrier->cur_count = 0;
}

void barrier(int numproc, barrier_t * mybarrier)
{
	pthread_mutex_lock(&(mybarrier->barrier_mutex));
	mybarrier->cur_count++;
	if (mybarrier->cur_count!=numproc) {
		pthread_cond_wait(&(mybarrier->barrier_cond), &(mybarrier->barrier_mutex));
	} else {
		mybarrier->cur_count=0;
		pthread_cond_broadcast(&(mybarrier->barrier_cond));
	}
	pthread_mutex_unlock(&(mybarrier->barrier_mutex));
}

double f(double a)
{
	return (4.0 / (1.0 + a * a));
}

class CPI : public jthread::Runnable{
	private:
		parm *p;

	public:
		CPI(parm *arg)
		{
			p = arg;
		}

		virtual ~CPI()
		{
		}

		virtual void Run()
		{
			int myid = p->id;
			int numprocs = p->noproc;
			int i;
			double PI25DT = 3.141592653589793238462643;
			double mypi = 0.0, pi, h, sum, x;
			double startwtime = 0.0, endwtime;

			if (myid == 0) {
				startwtime = clock();
			}
			barrier(numprocs, &barrier1);
			if (rootn==0) {
				finals[myid]=0;
			} else {
				h = 1.0 / (double) rootn;
				sum = 0.0;
				for (i = myid + 1; i <=rootn; i += numprocs) {
					x = h * ((double) i - 0.5);
					sum += f(x);
				}
				mypi = h * sum;
			}
			finals[myid] = mypi;

			barrier(numprocs, &barrier1);

			if (myid == 0) {
				pi = 0.0;
				for (i =0; i < numprocs; i++) {
					pi += finals[i];
				}
				endwtime = clock();
				std::cout << "pi is approximately " << pi << ", Error is " << fabs(pi - PI25DT) << std::endl;
				std::cout << "wall clock time = " << (endwtime-startwtime)/CLOCKS_PER_SEC << std::endl;
			}
		}
};

int main(int argc, char **argv)
{
	parm *arg;
	int n, 
			i;

	if (argc != 2) {
		std::cout << "usage: " << argv[0] << " n [where n is no. of thread]" << std::endl;
		exit(1);
	}
	n = atoi(argv[1]);
	if ((n < 1) || (n > MAX_THREAD)) {
		std::cout << "The no of thread should between 1 and " << MAX_THREAD << std::endl;
		exit(1);
	}

	/* setup barrier */
	barrier_init(&barrier1);

	/* allocate space for final result */
	finals = (double *) malloc(n * sizeof(double));

	rootn = 10000000;

	arg=(parm *)malloc(sizeof(parm)*n);

	try {
		jthread::ThreadPool group1(n);

		for (i = 0; i < n; i++) {
			arg[i].id = i;
			arg[i].noproc = n;

			group1.AttachThread(new CPI(&arg[i]));
		}

		group1.WaitForAll();
	} catch (jcommon::RuntimeException &e) {
		perror("Error:: ");
	}
	
	free(arg);
}