void sendRequestMulti()

in mcrouter/lib/carbon/connection/ExternalCarbonConnectionImpl-inl.h [257:326]
60 lines of code
12 McCabe index (conditional complexity)

  void sendRequestMulti(
      std::vector<std::reference_wrapper<const Request>>&& reqs,
      F&& f) {
    auto threadInfo = threadInfo_.lock();
    if (!threadInfo) {
      throw CarbonConnectionRecreateException(
          "Singleton<ThreadPool> was destroyed!");
    }

    auto cl = client_.lock();
    assert(cl);

    auto ctx =
        std::make_shared<std::vector<std::reference_wrapper<const Request>>>(
            std::move(reqs));

    for (size_t i = 0; i < ctx->size();) {
      auto num = cl->limitRequests(ctx->size() - i);

      if (num == 0) {
        // Hit outstanding limit.
        for (; i < ctx->size(); ++i) {
          f((*ctx)[i].get(),
            facebook::memcache::ReplyT<Request>(carbon::Result::LOCAL_ERROR));
        }
        break;
      }

      threadInfo->addTaskRemote([clientWeak = client_,
                                 ctx,
                                 i,
                                 num,
                                 f]() mutable {
        auto client = clientWeak.lock();
        if (!client) {
          folly::fibers::runInMainContext([&ctx, i, num, &f]() mutable {
            for (size_t cnt = 0; cnt < num; ++cnt, ++i) {
              f((*ctx)[i].get(),
                facebook::memcache::ReplyT<Request>(carbon::Result::UNKNOWN));
            }
          });
          return;
        }

        for (size_t cnt = 0; cnt + 1 < num; ++cnt, ++i) {
          const Request& req = (*ctx)[i];
          folly::fibers::addTaskFinally(
              [clientWeak, &req] {
                if (auto c = clientWeak.lock()) {
                  return c->sendRequest(req);
                }
                return facebook::memcache::ReplyT<Request>(
                    carbon::Result::UNKNOWN);
              },
              [f, &req](
                  folly::Try<facebook::memcache::ReplyT<Request>>&& r) mutable {
                f(req, std::move(r.value()));
              });
        }

        // Send last request in a batch on this fiber.
        const auto& req = (*ctx)[i].get();
        auto reply = client->sendRequest(req);
        folly::fibers::runInMainContext(
            [&req, &f, &reply]() mutable { f(req, std::move(reply)); });
      });

      i += num;
    }
  }