/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* ***************************************************************************
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as 
 *  published by the Free Software Foundation.
 *
 *  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.
 *
 *  As a special exception, you may use this file as part of a free software
 *  library without restriction.  Specifically, if other files instantiate
 *  templates or use macros or inline functions from this file, or you compile
 *  this file and link it with other files to produce an executable, this
 *  file does not by itself cause the resulting executable to be covered by
 *  the GNU General Public License.  This exception does not however
 *  invalidate any other reasons why the executable file might be covered by
 *  the GNU General Public License.
 *
 ****************************************************************************
 */
/* 
 * Author: Massimo Torquati <torquati@di.unipi.it> 
 * Date:   November 2014
 */

// SPM class exercise (Class Work 2)
// Consider the possibility to list all prime numbers in an interval [MIn, MAX] by:
//
//  - split the interval in a number of given subintervals nw (n workers)
//  - assig each subinterval to a farm worker
//  - the worker
//        for each i in the interval
//            checks if i is prime if yes it packs the value in an array
//            finally the array is sent to the gatherer thread
//  - the gatherer threads gets all results and produces an ordered lists
//    of all primes
//                        
//             (primality check in each partition) 
//                         
//                   |----> Worker -->|
//         Emitter --|----> Worker -->|--Collector
//                   |----> Worker -->|   
//   (splits input array          (gathers all sub-partitions)
//    in partitions)
//              

#include <vector>
#include <iostream>
#include <ff/farm.hpp>
using namespace ff;

// see http://en.wikipedia.org/wiki/Primality_test
bool is_prime(unsigned long long n) {
    if (n <= 3)  return n > 1; // 1 is not prime !
    
    if (n % 2 == 0 || n % 3 == 0) return false;

    for (unsigned long long i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0) 
            return false;
    }
    return true;
}


// stream type
struct Task_t {
    Task_t(unsigned long long n1, unsigned long long n2):n1(n1),n2(n2) {}
    const unsigned long long n1, n2;   // input range
    std::vector<unsigned long long> V; // output data
};

// splits the range [n1,n2] in nw sub-ranges each one of size ~(n2-n1)/nw 
struct Emitter: ff_node_t<Task_t> {
    Emitter(const ff_loadbalancer *lb,
            unsigned long long n1, unsigned long long n2) 
        :lb(lb),n1(n1),n2(n2) {}

    Task_t *svc(Task_t *) {
        const int nw = lb->getNWorkers();  // gets the total number of workers added to the farm
        const size_t  size = (n2 - n1) / nw;
        ssize_t more = (n2-n1) % nw;
        unsigned long long start = n1;
        unsigned long long stop  = n1;

        for(int i=0; i<nw; ++i) {
            start = stop;
            stop  = start + size + (more>0 ? 1:0);
            --more;

            Task_t *task = new Task_t(start, stop);
            lb->ff_send_out_to(task, i);
        }
        return EOS; // broadcast EOS to all workers
    }
    const ff_loadbalancer *lb;
    unsigned long long n1, n2;
};
struct Worker: ff_node_t<Task_t> {
    Task_t *svc(Task_t *in) {
        auto   &V   = in->V;
        unsigned long long n, n1(in->n1), n2(in->n2);
        while( (n=n1++) < n2 )  if (is_prime(n)) V.push_back(n);
        return in;
    }
};
struct Collector: ff_node_t<Task_t> {
    Task_t *svc(Task_t *in) {
        auto V = in->V;

        if (V.size())  // I may receive empty sub-partitions
            primes.insert(std::upper_bound(primes.begin(), primes.end(), V[0]),
                          V.begin(), V.end());
        delete in;
        return GO_ON;
    }
    void svc_end() { 
        for(size_t i=0;i<primes.size(); ++i) 
            std::cout << primes[i] << " ";
        std::cout << "\n";
    }
    std::vector<unsigned long long> primes;
};

int main(int argc, char *argv[]) {    
    if (argc<4) {
        std::cerr << "use: " << argv[0]  << " number1 number2 nworkers\n";
        return -1;
    }
    unsigned long long n1 = atoll(argv[1]);
    unsigned long long n2 = atoll(argv[2]);
    const int    nw       = atoi(argv[3]);

    std::vector<ff_node*> W;
    for(int i=0;i<nw; ++i) W.push_back(new Worker);
    Collector C;
    ff_farm<> farm(W, nullptr, &C);
    Emitter E(farm.getlb(), n1,n2); 
    farm.add_emitter(&E);  // replacing default emitter
    farm.cleanup_workers();
    if (farm.run_and_wait_end()<0) error("running farm\n");
    return 0;
}