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==== Pipeline with farm stage (sample code) ====
<code c++ pipefarm.cpp>
/* -*- 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.
 *
 ****************************************************************************
 */

#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;
}

</code>
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