Class MapGNode

example/E04-MapReduce.cpp:50–60

template<int MAP_TAG>
class MapGNode : public GNode {
public:
    CStatus run() override {
        auto param = CGRAPH_GET_GPARAM_WITH_NO_EMPTY(NumsGParam, PARAM_KEY);
        for (int i = 0; i < NUMS_PER_MAP; i++) {
            int num = param->random_nums_[MAP_TAG * NUMS_PER_MAP + i];
            param->map_results_[MAP_TAG][num]++;    // 实际上是线程安全的
        }
        return CStatus();
    }
};


class ReduceGNode : public GNode {