/home/mhx/git/github/libmoost/include/moost/process/sleeper.hpp

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/* vim:set ts=3 sw=3 sts=3 et: */
#ifndef FM_LAST_MOOST_PROCESS_SLEEPER_H_
#define FM_LAST_MOOST_PROCESS_SLEEPER_H_

#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/noncopyable.hpp>
#include <boost/enable_shared_from_this.hpp>

namespace moost { namespace process {

class sleeper : public boost::noncopyable
{
private:
   // This helper class avoids creating all the io_service and deadline_timer cruft right away.
   // It might be a user of moost::process::sleeper doesn't even go beyond creating an instance.
   class impl : public boost::enable_shared_from_this<impl>, public boost::noncopyable
   {
   public:
      impl()
        : m_sleeping(false)
        , m_ios()
        , m_timer(m_ios)
      {
      }

      void sleep()
      {
         if (!m_sleeping)
         {
            m_sleeping = true;
            on_timer();
            m_ios.run();
         }
      }

      void awaken()
      {
         m_sleeping = false;
         m_timer.cancel();
      }

   private:
      void on_timer()
      {
         if (m_sleeping)
         {
            m_timer.expires_from_now(boost::posix_time::time_duration(boost::posix_time::pos_infin));
            m_timer.async_wait(boost::bind(&impl::on_timer, shared_from_this()));
         }
      }

      bool m_sleeping;
      boost::asio::io_service m_ios;
      boost::asio::deadline_timer m_timer;
   };

public:
   sleeper()
   {
   }

   void sleep()
   {
      if (!m_impl)
      {
         m_impl.reset(new impl());
      }

      m_impl->sleep();
   }

   void awaken()
   {
      if (m_impl)
      {
         m_impl->awaken();
      }
   }

private:
   boost::shared_ptr<impl> m_impl;
};

} }

#endif