dlib C++ Library - multithreaded_object_extension.cpp

    // Copyright (C) 2007  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_MULTITHREADED_OBJECT_EXTENSIOn_CPP
    #define DLIB_MULTITHREADED_OBJECT_EXTENSIOn_CPP

    #include "multithreaded_object_extension.h"
    #include "create_new_thread_extension.h"

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        multithreaded_object::
        multithreaded_object (
        ):
            s(m_),
            is_running_(false),
            should_stop_(false),
            threads_started(0)
        {
        }

    // ----------------------------------------------------------------------------------------

        multithreaded_object::
        ~multithreaded_object (
        )
        {
            try
            {
                DLIB_ASSERT(number_of_threads_alive() == 0,
                       "\tmultithreaded_object::~multithreaded_object()"
                       << "\n\tYou have let a multithreaded object destruct itself before terminating its threads"
                       << "\n\tthis: " << this
                );
            }
            catch (std::exception& e)
            {
                std::cerr << e.what() << std::endl;
                assert(false);
                abort();
            }
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        clear (
        )
        {
            auto_mutex M(m_);
            stop();
            wait();
            dead_threads.clear();
            is_running_ = false;
            should_stop_ = false;
        }

    // ----------------------------------------------------------------------------------------

        bool multithreaded_object::
        is_running (
        ) const
        {
            auto_mutex M(m_);
            return is_running_;
        }

    // ----------------------------------------------------------------------------------------

        unsigned long multithreaded_object::
        number_of_threads_registered (
        ) const
        {
            auto_mutex M(m_);
            return thread_ids.size() + dead_threads.size();
        }

    // ----------------------------------------------------------------------------------------

        unsigned long multithreaded_object::
        number_of_threads_alive (
        ) const
        {
            auto_mutex M(m_);
            return threads_started;
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        wait (
        ) const
        {
            auto_mutex M(m_);

            DLIB_ASSERT(thread_ids.is_in_domain(get_thread_id()) == false,
                   "\tvoid multithreaded_object::wait()"
                   << "\n\tYou can NOT call this function from one of the threads registered in this object"
                   << "\n\tthis: " << this
            );

            while (threads_started > 0)
                s.wait();
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        start (
        )
        {
            auto_mutex M(m_);
            const unsigned long num_threads_registered = dead_threads.size() + thread_ids.size();
            // start any dead threads
            for (unsigned long i = threads_started; i < num_threads_registered; ++i)
            {
                if (create_new_thread<multithreaded_object,&multithreaded_object::thread_helper>(*this) == false)
                {
                    should_stop_ = true;
                    is_running_ = false;
                    throw thread_error();
                }
                ++threads_started;
            }
            is_running_ = true;
            should_stop_ = false;
            s.broadcast();
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        pause (
        )
        {
            auto_mutex M(m_);
            is_running_ = false;
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        stop (
        )
        {
            auto_mutex M(m_);
            should_stop_ = true;
            is_running_ = false;
            s.broadcast();
        }

    // ----------------------------------------------------------------------------------------

        bool multithreaded_object::
        should_stop (
        ) const
        {
            auto_mutex M(m_);
            DLIB_ASSERT(thread_ids.is_in_domain(get_thread_id()),
                   "\tbool multithreaded_object::should_stop()"
                   << "\n\tYou can only call this function from one of the registered threads in this object"
                   << "\n\tthis: " << this
            );
            while (is_running_ == false && should_stop_ == false)
                s.wait();
            return should_stop_;
        }

    // ----------------------------------------------------------------------------------------

        multithreaded_object::raii_thread_helper::
        raii_thread_helper(
            multithreaded_object& self_,
            thread_id_type id_
        ) : self(self_), id(id_){}

        multithreaded_object::raii_thread_helper::
        ~raii_thread_helper()
        {
            auto_mutex M(self.m_);
            if (self.thread_ids.is_in_domain(id))
            {
                mfp temp;
                thread_id_type id_temp;
                self.thread_ids.remove(id,id_temp,temp);
                // put this thread's registered function back into the dead_threads queue
                self.dead_threads.enqueue(temp);
            }

            --self.threads_started;
            // If this is the last thread to terminate then
            // signal that that is the case.
            if (self.threads_started == 0)
            {
                self.is_running_ = false;
                self.should_stop_ = false;
                self.s.broadcast();
            }
        }

    // ----------------------------------------------------------------------------------------

        void multithreaded_object::
        thread_helper(
        )
        {
            mfp mf;
            thread_id_type id = get_thread_id();

            // this guy's destructor does all the necessary cleanup in this function
            raii_thread_helper raii(*this, id);

            // if there is a dead_thread sitting around then pull it
            // out and put it into mf
            {
                auto_mutex M(m_);
                if (dead_threads.size() > 0)
                {
                    dead_threads.dequeue(mf);
                    mfp temp(mf);
                    thread_ids.add(id,temp);
                }
            }

            if (mf.is_set())
            {
                // call the registered thread function
                mf();
            }
        }

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_MULTITHREADED_OBJECT_EXTENSIOn_CPP