md5_bruteforce solution with SObjectizer-5.5.4 (SepAgents)

#include <iostream>
#include <chrono>
#include <array>
#include <iterator>

#include <so_5/all.hpp>

#include <md5_cpp11/all.hpp>

using namespace std;
using namespace std::chrono;

using password = array< char, 5 >;

ostream & operator<<( ostream & to, const password & pw )
{
    copy( begin(pw), end(pw), ostream_iterator< password::value_type >(to) );
    return to;
}

password::value_type next_byte( password::value_type b )
{
    switch( b )
    {
        case 'z' : return '0';
        case '9' : return 'a';
        default : return b + 1;
    }
}

void next_pass( password & p )
{
    for( auto e = p.rbegin(); e != p.rend(); ++e )
    {
        *e = next_byte( *e );
        if( '0' != *e )
            break;
    }
}

struct found : public so_5::rt::message_t
{
    const password m_result;

    found( const password & result ) : m_result( result ) {}
};

void do_brute_force( so_5::rt::environment_t & env )
{
    const auto hash = md5_cpp11::from_hex_string(
            "95ebc3c7b3b9f1d2c40fec14415d3cb8" );

    using namespace so_5::disp::thread_pool;

    auto coop = env.create_coop( so_5::autoname,
            create_private_disp( env, thread::hardware_concurrency() )->binder(
                    params_t{}.fifo( fifo_t::individual ) ) );

    const auto channel = env.create_local_mbox();

    // Result printer.
    coop->define_agent( so_5::rt::create_default_disp_binder() )
            .event( channel, [&env]( const found & evt ) {
                cout << "password: " << evt.m_result << endl;
                env.stop();
            } );

    // Workers.
    // Create a separate worker for every range.
    password start; start.fill( '0' );
    do {
        auto end = next_byte( start[ 0 ] );
        coop->define_agent().on_start( [channel, hash, start, end] {
                auto pw = start;
                while( pw[ 0 ] != end && md5_cpp11::make_digest( pw ) != hash )
                    next_pass( pw );

                if( pw[ 0 ] != end )
                    so_5::send< found >( channel, pw );
            } );
        start[ 0 ] = end;
    } while( start[ 0 ] != '0' );

    env.register_coop( move( coop ) );
}

double time_spent( const steady_clock::time_point s )
{
    const auto e = steady_clock::now();
    return duration_cast< milliseconds >( e - s ).count() / 1000.0;
}

int main()
{
    try
    {
        const auto started_at = steady_clock::now();

        so_5::launch( do_brute_force );

        cout << "time: " << time_spent( started_at ) << "s" << endl;

        return 0;
    }
    catch( const exception & x )
    {
        cerr << "Exception: " << x.what() << endl;
    }

    return 2;
}