#### Source listing for Timer.5

    //
    // timer.cpp
    // ~~~~~~~~~
    //
    // Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
    //
    // Distributed under the Boost Software License, Version 1.0. (See accompanying
    // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    //

    #include <functional>
    #include <iostream>
    #include <thread>
    #include <asio.hpp>

    class printer
    {
    public:
      printer(asio::io_context& io)
        : strand_(asio::make_strand(io)),
          timer1_(io, asio::chrono::seconds(1)),
          timer2_(io, asio::chrono::seconds(1)),
          count_(0)
      {
        timer1_.async_wait(asio::bind_executor(strand_,
              std::bind(&printer::print1, this)));

        timer2_.async_wait(asio::bind_executor(strand_,
              std::bind(&printer::print2, this)));
      }

      ~printer()
      {
        std::cout << "Final count is " << count_ << std::endl;
      }

      void print1()
      {
        if (count_ < 10)
        {
          std::cout << "Timer 1: " << count_ << std::endl;
          ++count_;

          timer1_.expires_at(timer1_.expiry() + asio::chrono::seconds(1));

          timer1_.async_wait(asio::bind_executor(strand_,
                std::bind(&printer::print1, this)));
        }
      }

      void print2()
      {
        if (count_ < 10)
        {
          std::cout << "Timer 2: " << count_ << std::endl;
          ++count_;

          timer2_.expires_at(timer2_.expiry() + asio::chrono::seconds(1));

          timer2_.async_wait(asio::bind_executor(strand_,
                std::bind(&printer::print2, this)));
        }
      }

    private:
      asio::strand<asio::io_context::executor_type> strand_;
      asio::steady_timer timer1_;
      asio::steady_timer timer2_;
      int count_;
    };

    int main()
    {
      asio::io_context io;
      printer p(io);
      std::thread t([&]{ io.run(); });
      io.run();
      t.join();

      return 0;
    }

Return to Timer.5 - Synchronising completion handlers in multithreaded programs