samples/tcp_service/main.cpp

#include <userver/utest/using_namespace_userver.hpp>

#include <userver/components/minimal_component_list.hpp>
#include <userver/components/tcp_acceptor_base.hpp>
#include <userver/utils/daemon_run.hpp>
#include <userver/yaml_config/merge_schemas.hpp>
 
namespace samples::tcp {
 
class Hello final : public components::TcpAcceptorBase {
public:
    static constexpr std::string_view kName = "tcp-hello";
 
    // Component is valid after construction and is able to accept requests
    Hello(const components::ComponentConfig& config, const components::ComponentContext& context)
        : TcpAcceptorBase(config, context), greeting_(config["greeting"].As<std::string>("hi")) {}
 
    void ProcessSocket(engine::io::Socket&& sock) override;
 
    static yaml_config::Schema GetStaticConfigSchema();
 
private:
    const std::string greeting_;
};
 
}  // namespace samples::tcp

 
namespace samples::tcp {

void Hello::ProcessSocket(engine::io::Socket&& sock) {
    std::string data;
    data.resize(2);
 
    while (!engine::current_task::ShouldCancel()) {
        const auto read_bytes = sock.ReadAll(data.data(), 2, {});
        if (read_bytes != 2 || data != "hi") {
            sock.Close();
            return;
        }
 
        const auto sent_bytes = sock.SendAll(greeting_.data(), greeting_.size(), {});
        if (sent_bytes != greeting_.size()) {
            return;
        }
    }
}

yaml_config::Schema Hello::GetStaticConfigSchema() {
    return yaml_config::MergeSchemas<TcpAcceptorBase>(R"(
    type: object
    description: |
      Component for accepting incoming TCP connections and responding with some
      greeting as long as the client sends 'hi'.
    additionalProperties: false
    properties:
      greeting:
          type: string
          description: greeting to send to client
          defaultDescription: hi
  )");
}
 
}  // namespace samples::tcp

int main(int argc, const char* const argv[]) {
    const auto component_list = components::MinimalComponentList().Append<samples::tcp::Hello>();
 
    return utils::DaemonMain(argc, argv, component_list);
}