Example of Transaction Processing

/** Recursion for enumeration of all possible transaction schedules */
void gen_all_sch_r(const xa_coll_t& xa_coll,
    vector<xa_t::const_iterator>& xac_pos,
    vector<xa_op_t>& sch)
{
    size_t num_xa = xa_coll.size();

    //if(xac_pos.empty())
    //{
    //    xac_pos = vector<xa_coll_t::const_iterator>(num_xa);
    //}

    /*
    vector<size_t> v(4);
    iota(v.begin(), v.end(), 0);
    print_coll(cout, v.begin(), v.end(), " ", "\n");
    while(next_permutation(v.begin(), v.end()))
    {
        print_coll(cout, v.begin(), v.end(), " ", "\n");
    }
    //copy(v.begin(), v.end(), ostream_iterator<int>(cout, " "));
    */

    // Have all transaction operations been added to the schedule?
    bool all_xa_op_used = true;
    for(size_t i = 0; i < num_xa; i++)
    {
        if(xac_pos[i] != xa_coll[i].end())
        {
            all_xa_op_used = false;
        }
    }

    if(all_xa_op_used)
    {
        // We have found another schedule
        cout << "SCHEDULE" << endl;
        cout << sch;

        // TODO: Is this schedule serializable? Use graphs and cycles.
    }
    else
    {
        // Still need to recurse one level lower to continue filling
        // the schedule
        for(size_t i = 0; i < num_xa; i++)
        {
            if(xac_pos[i] != xa_coll[i].end())
            {
                sch.push_back(*xac_pos[i]);
                xac_pos[i]++;
                gen_all_sch_r(xa_coll, xac_pos, sch);
                xac_pos[i]--;
                sch.pop_back();
            }
        }
    }

}

void gen_all_sch(const xa_coll_t& xa_coll)
{
    vector<xa_op_t> sch;
    vector<xa_t::const_iterator> xac_pos(xa_coll.size());

    for(size_t pos = 0; pos < xa_coll.size(); pos++)
    {
        xac_pos[pos] = xa_coll[pos].cbegin();
    }

    gen_all_sch_r(xa_coll, xac_pos, sch);
}