so_5/mchain_handler_formats/main.cpp

/*
 * An example for demonstration of different format of message handlers for mchain.
 */

#include <iostream>
#include <string>

// Main SObjectizer header file.
#include <so_5/all.hpp>

// Types of messages and signals to be placed into mchain.
struct two_ints
{
  int a, b;
};

struct delayed_two_ints
{
  int a, b;
};

struct just_signal final : public so_5::signal_t {};
struct periodic_signal final : public so_5::signal_t {};

void demo()
{
  // A SObjectizer instance.
  so_5::wrapped_env_t sobj;

  // Message chain to be used.
  auto ch = so_5::create_mchain( sobj,
      // Wait on overloaded mchain for 5min.
      std::chrono::minutes{5},
      // No more than 3 messages in chain.
      3u,
      // Space for mchain will be preallocated.
      so_5::mchain_props::memory_usage_t::preallocated,
      // What to do on overflow.
      // This value has no sence because we use too large time limit.
      // Because of that use hardest case.
      so_5::mchain_props::overflow_reaction_t::abort_app );

  // We must store timer_id for periodic signal somewhere.
  // Otherwise periodic signal will be canceled automaticallly right after
  // exit from send_periodic function.
  so_5::timer_id_t periodic_signal_timer;

  // Spawn another thread to fill mchain.
  std::thread worker{ [&]{
    // Send a string as message.
    so_5::send< std::string >( ch, "Hello!" );
    // Send int as message.
    so_5::send< int >( ch, 42 );
    // Send struct instance as message.
    so_5::send< two_ints >( ch, 0, 1 );
    // Send delayed messages.
    so_5::send_delayed< delayed_two_ints >(
        ch, std::chrono::milliseconds{150}, 1, 2 );
    // Send signal.
    so_5::send< just_signal >( ch );
    // Send periodic signal.
    periodic_signal_timer = so_5::send_periodic< periodic_signal >(
        ch, std::chrono::milliseconds{20}, std::chrono::milliseconds{150} );
  } };

  // Read content of mchain.
  // We expect exactly 8 messages/signals.
  receive( from( ch ).handle_n( 8 ),
    // Message instance by const reference.
    []( const std::string & v ) { std::cout << "str: " << v << std::endl; },
    // Message instance by value (efficient for small types like int).
    []( int v ) { std::cout << "int: " << v << std::endl; },
    // Message instance via mhood_t value.
    []( so_5::mhood_t< two_ints > v ) {
      std::cout << "two_ints: " << v->a << ", " << v->b << std::endl;
    },
    // Message instance via const reference to mhood_t.
    []( const so_5::mhood_t< delayed_two_ints > & v ) {
      std::cout << "delayed_two_ints: " << v->a << ", " << v->b << std::endl;
    },
    // Signal handler via mhood_t value.
    []( so_5::mhood_t< just_signal > ) {
      std::cout << "just signal" << std::endl;
    },
    // Signal handler via const reference to mhood_t.
    []( const so_5::mhood_t< periodic_signal > & ) {
      std::cout << "periodic signal" << std::endl;
    } );

  // Close channel with dropping all its content.
  // It has sence because timer thread can send periodic signals to
  // mchain while we wait on worker.join().
  close_drop_content( so_5::exceptions_enabled, ch );

  worker.join();

  // SObjectizer will be stopped automatically.
}

int main()
{
  try
  {
    demo();
  }
  catch( const std::exception & ex )
  {
    std::cerr << "Error: " << ex.what() << std::endl;
  }

  return 0;
}