ranczo-io/include/boost/asio/basic_repeating_timer.hpp

#ifndef BOOST_ASIO_REPEATING_TIMER_H_INCLUDED
#define BOOST_ASIO_REPEATING_TIMER_H_INCLUDED

// Adapted from the original, developed 2007 by David C. Wyles (http:///www.codegorilla.co.uk)
// released for public consumption under the same
// licensing policy as the boost library http://www.boost.org/LICENSE_1_0.txt
//
// most people will use the repeating_timer typedef for working with posix time
//
// Is is based on the basic_deadline_timer
//
// Updated 2021 by Michael Haben, for compatibility with Boost 1.77 / ASIO 1.18.2
// - uses an executor instead of an io_service or io_context.

#include <boost/asio.hpp>
#include <boost/bind/bind.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/thread/recursive_mutex.hpp>
#include <boost/weak_ptr.hpp>

namespace boost {
namespace asio {
    // basic repeating timer with start/stop semantics.

    template < typename Time, typename TimeTraits = boost::asio::time_traits< Time >, typename Executor = boost::asio::any_io_executor >
    class basic_repeating_timer {
      public:
        typedef boost::asio::basic_deadline_timer< Time > timer_type;

        explicit basic_repeating_timer(Executor ex) : ex_(ex) {}

        ~basic_repeating_timer() {
            stop();
        }

        template < typename WaitHandler >
        void start(typename timer_type::duration_type const & repeat_interval, WaitHandler handler) {
            boost::recursive_mutex::scoped_lock guard(lock_);
            {
                // cleanup code, cancel any existing timer
                handler_.reset();
                if(timer_) {
                    timer_->cancel();
                }
                timer_.reset();
            }

            // create new handler.
            handler_.reset(new handler_impl< WaitHandler >(handler));
            // create new timer
            timer_ = internal_timer::create(this->ex_, repeat_interval, handler_);
        }

        void stop() {
            boost::recursive_mutex::scoped_lock guard(lock_);
            {
                // cleanup code.
                handler_.reset();
                if(timer_) {
                    timer_->cancel();
                }
                timer_.reset();
            }
        }

        void cancel() {
            stop();
        }

        // changes the interval the next time the timer is fired.
        void change_interval(typename timer_type::duration_type const & repeat_interval) {
            boost::recursive_mutex::scoped_lock guard(lock_);
            if(timer_) {
                timer_->change_interval(repeat_interval);
            }
        }

      private:
        const Executor & ex_;
        boost::recursive_mutex lock_;
        class internal_timer;
        typedef boost::shared_ptr< internal_timer > internal_timer_ptr;
        typedef boost::asio::executor executor_type;
        internal_timer_ptr timer_;

        class handler_base;
        boost::shared_ptr< handler_base > handler_;

        class handler_base {
          public:
            virtual ~handler_base() {}
            virtual void handler(boost::system::error_code const &) = 0;
        };

        template < typename HandlerFunc >
        class handler_impl : public handler_base {
          public:
            handler_impl(HandlerFunc func) : handler_func_(func) {}
            virtual void handler(boost::system::error_code const & result) {
                handler_func_(result);
            }
            HandlerFunc handler_func_;
        };

        class internal_timer : public boost::enable_shared_from_this< internal_timer > {
          public:
            static internal_timer_ptr create(const Executor & ex,
              typename timer_type::duration_type const & repeat_interval,
              boost::shared_ptr< handler_base > const & handler) {
                internal_timer_ptr timer(new internal_timer(ex));
                timer->start(repeat_interval, handler);
                return timer;
            }

            void cancel() {
                boost::recursive_mutex::scoped_lock guard(lock_);
                timer_.cancel();
            }

            void change_interval(typename timer_type::duration_type const & repeat_interval) {
                boost::recursive_mutex::scoped_lock guard(lock_);
                interval_ = repeat_interval;
            }

          private:
            timer_type timer_;
            boost::weak_ptr< handler_base > handler_;
            typename timer_type::duration_type interval_;
            boost::recursive_mutex lock_;

            internal_timer(boost::asio::any_io_executor ex) : timer_(ex) {}

            void start(typename timer_type::duration_type const & repeat_interval, boost::shared_ptr< handler_base > const & handler) {
                // only EVER called once, via create
                interval_ = repeat_interval;
                handler_  = handler;

                timer_.expires_from_now(interval_);
                timer_.async_wait(boost::bind(&internal_timer::handle_timeout, this->shared_from_this(), boost::asio::placeholders::error));
            }

            void handle_timeout(boost::system::error_code const & error) {
                // we lock in the timeout to block the cancel operation until this timeout completes
                boost::recursive_mutex::scoped_lock guard(lock_);
                {
                    // do the fire.
                    boost::shared_ptr< handler_base > Handler = handler_.lock();
                    if(Handler) {
                        try {
                            Handler->handler(error);
                        } catch(std::exception const & e) {
                            // consume for now, no much else we can do, we don't want to damage the
                            // io_context thread
                            ( void ) e;
                        }
                    }
                }

                if(!error) {
                    // check if we need to reschedule.
                    boost::shared_ptr< handler_base > Handler = handler_.lock();
                    if(Handler) {
                        timer_.expires_from_now(interval_);
                        timer_.async_wait(
                          boost::bind(&internal_timer::handle_timeout, this->shared_from_this(), boost::asio::placeholders::error));
                    }
                }
            }
        };
    };

    typedef basic_repeating_timer< boost::posix_time::ptime > repeating_timer;
} // namespace asio
} // namespace boost

#endif