Pipeline with farm stage (sample code)

pipefarm.cpp
/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
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#include <cstdlib>
#include <cstdio>
#include <ff/pipeline.hpp>
#include <ff/farm.hpp>
 
using namespace ff;
 
 
// generic stage
class Stage1: public ff_node {
public:
    Stage1(unsigned streamlen):streamlen(streamlen), seed(111) {}
 
    int svc_init() {
        srandom(seed);
        return 0;
    }
 
    void * svc(void *) {
        // f
        for(size_t i=0;i<streamlen;++i)
            ff_send_out(new long(random() % 1000000));
 
        return NULL;
    }
private:    
    unsigned streamlen;
    unsigned seed;
};
 
class Stage2: public ff_node {
public:
    void *svc(void *task) {
        // g
        long *t = static_cast<long*>(task);
        usleep(*t);
        return task;
    }
};
 
class Stage3: public ff_node {
public:
    void *svc(void *task) {
        // h
        long *t = static_cast<long*>(task);
        printf("received %ld\n", *t);
        delete t;
        return GO_ON;
    }
};
 
int main(int argc, char * argv[]) {
    if (argc!=3) {
        std::cerr << "use: "  << argv[0] << " streamlen nworkers\n";
        return -1;
    }
    long streamlen = atol(argv[1]);
    long nworkers  = atoi(argv[2]);
 
    ff_pipeline pipe;
 
    pipe.add_stage(new Stage1(streamlen));
 
    ff_farm<> farm;
    // to use an ordering farm comment the previous line and uncomment the next one
    // ff_ofarm farm;
    std::vector<ff_node*> w;
    for(int i=0;i<nworkers;++i)
        w.push_back(new Stage2);
    farm.add_workers(w);
    // comment the next line in case of ordering farm
    farm.add_collector(NULL);
 
    pipe.add_stage(&farm);
    pipe.add_stage(new Stage3);
 
    if (pipe.run_and_wait_end()<0) {
        error("running pipeline\n");
        return -1;
    }
    std::cerr << "DONE, pipe  time= " << pipe.ffTime() << " (ms)\n";
    //pipe.ffStats(std::cerr);
    return 0;
}