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===== Master worker (sample code) =====
<code c++ masterworker.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.
 *
 ****************************************************************************
 */

/*  Example of master-worker computation:  
 *               
 *                       --------------------- <--
 *                      |                     |   |
 *                      |        ---> Worker--    |
 *                      v       |                 |
 *                 Scheduler --- ---> Worker------ 
 *                      ^       |
 *                      |        ---> Worker--
 *                      |                     |
 *                       ---------------------
 *
 *
 */



#include <cstdlib>
#include <cstdio>
#include <ff/farm.hpp>

using namespace ff;

class Scheduler: public ff_node {
public:
    Scheduler(unsigned streamlen, ff_loadbalancer *lb=0):
        lb(lb), numtasks(streamlen), seed(111) {}

    int svc_init() {
        srandom(seed);
        return 0;
    }
    
    void * svc(void *task) {
        if (task==NULL) { // first time
            for(size_t i=0;i<numtasks;++i)
                ff_send_out(new long(random() % 10));
            return GO_ON;
        }
        const long t = *(static_cast<long*>(task));
        printf("Scheduler: got %ld from %d\n", t, lb->get_channel_id());
        if ( t > 0 ) ff_send_out(task);
        else --numtasks;
        
        return (numtasks>0)?GO_ON:NULL;
    }
private:    
    ff_loadbalancer *lb;
    unsigned numtasks;
    unsigned seed;
};

class Worker: public ff_node {
public:
    void *svc(void *task) {
        long *t = static_cast<long*>(task);
        printf("Worker(%d): got %ld\n", get_my_id(), *t);
        --*t;        
        return task;
    }
};

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_farm<> farm;
    farm.add_emitter(new Scheduler(streamlen, farm.getlb()));

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

    farm.wrap_around();

    if (farm.run_and_wait_end()<0) {
        error("running farm\n");
        return -1;
    }
    std::cerr << "DONE, pipe  time= " << farm.ffTime() << " (ms)\n";
    return 0;
}
</code>