so_5/named_dispatchers_layer/main.cpp

/*
 * An example of usage of SObjectizer's layer for holding a dictionary of named
 * dispatchers.
 */
#include <iostream>

#include <so_5/all.hpp>

// Implemetation of SObjectizer's layer that plays a role of
// a dictionary of named one_thread dispatchers.
class disp_binder_dictionary_layer_t : public so_5::layer_t
{
  // Type of dictionary for holding dispatcher binders.
  using map_t = std::map<std::string, so_5::disp_binder_shptr_t, std::less<>>;

  // Because layer can be used from different worker threads it should
  // be protected.
  std::mutex m_lock;

  // The dictionary.
  map_t m_dict;

public:
  // There is no need to override start()/shutdown()/wait() methods
  // because the basic implementation does nothing.

  // An interface of dictionary.
  
  // Add a new binder if there is no such name in the dictionary.
  void add(
    const std::string & name,
    so_5::disp_binder_shptr_t binder)
  {
    std::lock_guard<std::mutex> l{m_lock};
    auto [it, inserted] = m_dict.emplace(name, std::move(binder));
    (void)it; // To suppress warnings about unused variables.
    if(!inserted)
      throw std::runtime_error(name + ": is not unique name");
  }

  // Try find binder in the dictionary.
  // Absence of a binder is not an error.
  std::optional<so_5::disp_binder_shptr_t>
  try_get(std::string_view name) noexcept
  {
    std::lock_guard<std::mutex> l{m_lock};
    if(const auto it = m_dict.find(name); it != m_dict.end())
      return { it->second };
    else
      return std::nullopt;
  }

  // Try get binder from the dictinary.
  // Absence of a binder is reported by an exception.
  so_5::disp_binder_shptr_t
  get(std::string_view name)
  {
    auto r = try_get(name);
    if(!r) throw std::runtime_error("binder is not found");
    return std::move(*r);
  }
};

// Type of demo agent to be used in the example.
//
// This agent tells the parent about its start and then deregisters itself.
//
class a_child_t final : public so_5::agent_t
{
public:
  // Type of signal to be sent to the parent.
  struct i_am_completed final : public so_5::signal_t {};

  a_child_t(context_t ctx, so_5::mbox_t parent)
    : so_5::agent_t{std::move(ctx)}
    , m_parent{std::move(parent)}
  {}

  void so_evt_start() override
  {
    so_5::send<i_am_completed>(m_parent);

    so_deregister_agent_coop_normally();
  }

private:
  const so_5::mbox_t m_parent;
};

// Another type of demo agent to be used in the example.
class a_parent_t final : public so_5::agent_t
{
public:
  a_parent_t(context_t ctx, std::string disp_name)
    : so_5::agent_t{std::move(ctx)}
    , m_disp_name{std::move(disp_name)}
  {}

  void so_define_agent() override
  {
    so_subscribe_self().event(
      [this](mhood_t<a_child_t::i_am_completed>) {
        // We can finish our work too.
        std::cout << "child from '" << m_disp_name << "' completed"
            << std::endl;
        so_deregister_agent_coop_normally();
      });
  }

  void so_evt_start() override
  {
    // Create a new child on the specified dispatcher.
    so_5::introduce_child_coop( *this,
      [this](so_5::coop_t & coop) {
        auto binder = so_environment().query_layer<
            disp_binder_dictionary_layer_t
          >()->get(m_disp_name);
        coop.make_agent_with_binder<a_child_t>(binder, so_direct_mbox());
      });
  }

private:
  const std::string m_disp_name;
};

int main()
{
  so_5::launch(
    [](so_5::environment_t & env) {
      // Create several dispatchers and give them names.
      auto * layer = env.query_layer<disp_binder_dictionary_layer_t>();

      layer->add("first",
          so_5::disp::one_thread::make_dispatcher(env).binder());
      layer->add("second",
          so_5::disp::one_thread::make_dispatcher(env).binder());
      layer->add("third",
          so_5::disp::one_thread::make_dispatcher(env).binder());

      // Create several parent agents. All of them will work on
      // the default dispatcher.
      env.register_agent_as_coop(env.make_agent<a_parent_t>("first"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("second"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("third"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("second"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("first"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("third"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("third"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("third"));
      env.register_agent_as_coop(env.make_agent<a_parent_t>("third"));

      // Wait while all parents finish their work.
    },
    [](so_5::environment_params_t & params) {
      // Our layer should be created and stored in params.
      params.add_layer(std::make_unique<disp_binder_dictionary_layer_t>());
    });

  return 0;
}