===== Sample FastFlow farms =====
These are the programs used in the course notes. Comments may be found in the course notes book. 

<code c++ farm1.cpp>
#include <vector>
#include <iostream>
#include <ff/farm.hpp>


using namespace ff;

class Worker: public ff_node {
public:
    
    void * svc(void * task) {
        int * t = (int *)task;
        std::cout << "Worker got " << *t << std::endl;
        (*t)++;
      	std::cout << "Worker emitting " << *t << std::endl;
        return t;
    }
};

class Collector: public ff_node {
public:
    void * svc(void * task) {
        int * t = (int *)task;
        std::cout << "Collector received " << *t << "\n";
        if (*t == -1) return NULL;
        return task;
    }
};

// the load-balancer filter
class Emitter: public ff_node {
public:
    Emitter(int max_task):ntask(max_task) {};

    void * svc(void *) {	
        int * task = new int(ntask);
        --ntask;
        if (ntask<0) return NULL;
        std::cout << "Emitting task " << ntask << std::endl;;
        return task;
    }
private:
    int ntask;
};


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

    if (argc<3) {
        std::cerr << "use: " 
                  << argv[0] 
                  << " nworkers streamlen\n";
        return -1;
    }
    
    int nworkers=atoi(argv[1]);
    int streamlen=atoi(argv[2]);

    if (!nworkers || !streamlen) {
        std::cerr << "Wrong parameters values\n";
        return -1;
    }
    
    ff_farm<> farm;
    
    Emitter E(streamlen);
    farm.add_emitter(&E);

    std::vector<ff_node *> w;
    for(int i=0;i<nworkers;++i) w.push_back(new Worker);
    farm.add_workers(w); 

    Collector C;
    farm.add_collector(&C);
    
    if (farm.run_and_wait_end()<0) {
        error("running farm\n");
        return -1;
    }
    std::cerr << "DONE, time= " << farm.ffTime() << " (ms)\n";
    farm.ffStats(std::cerr);

    return 0;
}
</code>

<code c++ farme.cpp>
#include <vector>
#include <iostream>
#include <ff/farm.hpp>


using namespace ff;

class Worker: public ff_node {
public:
    void * svc(void * task) {
        int * t = (int *)task;
        (*t)++;
        return task;
    }
};


class Collector: public ff_node {
public:
    void * svc(void * task) {
        int * t = (int *)task;
        std::cout << "Collector got " << *t << std::endl;
        return GO_ON;
    }
};

class Emitter: public ff_node {
public:
    Emitter(int n) {
        streamlen = n; 
        task = 0; 
    };

    void * svc(void *) {	
        sleep(1);
        task++;
        int * t = new int(task);
        if (task<streamlen) 
            return t;
        else 
            return NULL; 
    }

private:
    int streamlen;
    int task; 
};


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

    if (argc<3) {
        std::cerr << "use: " 
                  << argv[0] 
                  << " nworkers streamlen\n";
        return -1;
    }
    
    int nworkers=atoi(argv[1]);
    int streamlen=atoi(argv[2]);

    if (!nworkers || !streamlen) {
        std::cerr << "Wrong parameters values\n";
        return -1;
    }
    
    ff_farm<> farm; // farm object
    
    Emitter E(streamlen);
    farm.add_emitter(&E);

    std::vector<ff_node *> w;
    for(int i=0;i<nworkers;++i) w.push_back(new Worker);
    farm.add_workers(w); // add all workers to the farm

    Collector C;
    farm.add_collector(&C);
    
    if (farm.run_and_wait_end()<0) {
        error("running farm\n");
        return -1;
    }
    return 0;
}
</code>

<code c++ farmNoC.cpp>
#include <vector>
#include <iostream>
#include <ff/farm.hpp>

static int * results; 

typedef struct task_t {
    int i; 
    int t; 
} TASK; 

using namespace ff;

class Worker: public ff_node {
public:
    void * svc(void * task) {
        TASK * t = (TASK *) task; 
        results[t->i] = ++(t->t);
        return GO_ON;
    }
};


class Emitter: public ff_node {
public:
    Emitter(int n) {
        streamlen = n; 
        task = 0; 
    };

    void * svc(void *) {	
        task++;
        TASK * t = (TASK *) calloc(1,sizeof(TASK));
        t->i = task;
        t->t = task*task;
        if (task<streamlen) 
            return t;
        else 
            return NULL; 
    }

private:
    int streamlen;
    int task; 
};


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

    int nworkers=atoi(argv[1]);
    int streamlen=atoi(argv[2]);
    results = (int *) calloc(streamlen,sizeof(int));
    
    ff_farm<> farm;
    
    Emitter E(streamlen);
    farm.add_emitter(&E);

    std::vector<ff_node *> w;
    for(int i=0;i<nworkers;++i)
        w.push_back(new Worker);
    farm.add_workers(w);

    std::cout << "Before starting computation" << std::endl;
    for(int i=0; i<streamlen; i++) 
        std::cout << i << " : " << results[i] << std::endl;
    if (farm.run_and_wait_end()<0) {
        error("running farm\n");
        return -1;
    }
    std::cout << "After computation" << std::endl;
    for(int i=0; i<streamlen; i++) 
        std::cout << i << " : " << results[i] << std::endl;
    return 0;
}
</code>