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/* 
 * Author: Massimo Torquati <torquati@di.unipi.it> 
 * Date:   November 2014
 */

//
// Toy example to test FastFlow farm.
// It finds the prime numbers in the range (n1,n2) using a farm + feedback.
//
//                   |----> Worker --
//         Emitter --|----> Worker --|--
//           ^       |----> Worker --   |
//           |__________________________|
//
//  -   The Emitter generates all number between n1 and n2 and then waits 
//      to receive primes from the Workers.
//  -   The Worker check if the number is prime (by using the is_prime function), 
//      if yes then it sends the prime number back to the Emitter.
//
//  Usage example:
//    ./farm_primes 1900 2000 3 | tr -s ' ' '\n' | sort -n


#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;
}
struct Emitter: ff_node_t<long> {
    Emitter(ff_loadbalancer *lb, 
            unsigned long long n1, unsigned long long n2)
        :lb(lb),n1(n1),n2(n2) {}

    long *svc(long *x) {
        if (x == nullptr) { // first time
            unsigned long long n;
            while( (n=n1++) <= n2 ) ff_send_out((void*)n);
            lb->broadcast_task(EOS);
            return GO_ON;
        }
        std::cout << reinterpret_cast<long>(x) << " ";
        return GO_ON;
    }
    ff_loadbalancer *const lb;
    unsigned long long n1,n2;
};
struct Worker: ff_node_t<long> {
    long *svc(long *in) {
        if (is_prime(reinterpret_cast<long>(in))) return in;
        return GO_ON;
    }
};

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);
    ff_farm<> farm(W); // by default adds an emitter and a collector
    Emitter E(farm.getlb(), n1,n2);
    farm.add_emitter(&E);    // replacing the default emitter

    farm.remove_collector(); // removing the default collector
    farm.wrap_around();      // adds feedback channel between worker and emitter
    farm.run_and_wait_end();
    std::cout << "\n\n";
    return 0;
}