ChannelElement.hpp

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/***************************************************************************
  tag: Peter Soetens  Thu Oct 22 11:59:07 CEST 2009  ChannelElement.hpp

                        ChannelElement.hpp -  description
                           -------------------
    begin                : Thu October 22 2009
    copyright            : (C) 2009 Sylvain Joyeux
    email                : sylvain.joyeux@m4x.org

 ***************************************************************************
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 *   version 2 of the License.                                             *
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#ifndef ORO_CHANNEL_ELEMENT_HPP
#define ORO_CHANNEL_ELEMENT_HPP

#include <boost/intrusive_ptr.hpp>
#include <boost/call_traits.hpp>
#include "ChannelElementBase.hpp"
#include "../ConnPolicy.hpp"
#include "../FlowStatus.hpp"
#include "../os/MutexLock.hpp"

#include <boost/bind.hpp>

namespace RTT { namespace base {


    template<typename T>
    class ChannelElement : virtual public ChannelElementBase
    {
    public:
        typedef boost::intrusive_ptr< ChannelElement<T> > shared_ptr;
        typedef T value_t;
        typedef typename boost::call_traits<T>::param_type param_t;
        typedef typename boost::call_traits<T>::reference reference_t;

        shared_ptr getOutput()
        {
             return ChannelElementBase::narrow<T>(ChannelElementBase::getOutput().get());
        }

        shared_ptr getInput()
        {
            return ChannelElementBase::narrow<T>(ChannelElementBase::getInput().get());
        }

        virtual WriteStatus data_sample(param_t sample, bool reset = true)
        {
            typename ChannelElement<T>::shared_ptr output = boost::static_pointer_cast< ChannelElement<T> >(getOutput());
            if (output)
                return output->data_sample(sample, reset);
            return WriteSuccess;
        }

        virtual value_t data_sample()
        {
            typename ChannelElement<T>::shared_ptr input = boost::static_pointer_cast< ChannelElement<T> >(getInput());
            if (input)
                return input->data_sample();
            return value_t();
        }

        virtual WriteStatus write(param_t sample)
        {
            typename ChannelElement<T>::shared_ptr output = getOutput();
            if (output)
                return output->write(sample);
            return NotConnected;
        }

        virtual FlowStatus read(reference_t sample, bool copy_old_data = true)
        {
            typename ChannelElement<T>::shared_ptr input = this->getInput();
            if (input)
                return input->read(sample, copy_old_data);
            else
                return NoData;
        }
    };

    template<typename T>
    class MultipleInputsChannelElement : virtual public MultipleInputsChannelElementBase, virtual public ChannelElement<T>
    {
    public:
        typedef boost::intrusive_ptr< MultipleInputsChannelElement<T> > shared_ptr;
        typedef typename ChannelElement<T>::value_t value_t;
        typedef typename ChannelElement<T>::param_t param_t;
        typedef typename ChannelElement<T>::reference_t reference_t;

        MultipleInputsChannelElement()
            : last()
        {}

        virtual value_t data_sample()
        {
            RTT::os::SharedMutexLock lock(inputs_lock);
            typename ChannelElement<T>::shared_ptr input = currentInput();
            if (input) {
                return input->data_sample();
            }
            return value_t();
        }

        virtual FlowStatus read(reference_t sample, bool copy_old_data = true)
        {
            FlowStatus result = NoData;
            RTT::os::SharedMutexLock lock(inputs_lock);

            // read and iterate if necessary.
            select_reader_channel( boost::bind( &MultipleInputsChannelElement<T>::do_read, this, boost::ref(sample), boost::ref(result), _1, _2), copy_old_data );
            return result;
        }

    private:
        typename ChannelElement<T>::shared_ptr currentInput() {
            typename ChannelElement<T>::shared_ptr last = this->last;
            if ( !last && !inputs.empty() ) last = inputs.front()->template narrow<T>();
            return last;
        }

        bool do_read(reference_t sample, FlowStatus& result, bool copy_old_data, typename ChannelElement<T>::shared_ptr& input)
        {
            assert( result != NewData );
            if ( input ) {
                FlowStatus tresult = input->read(sample, copy_old_data);
                // the result trickery is for not overwriting OldData with NoData.
                if (tresult == NewData) {
                    result = tresult;
                    return true;
                }
                // stores OldData result
                if (tresult > result)
                    result = tresult;
            }
            return false;
        }

        template<typename Pred>
        void select_reader_channel(Pred pred, bool copy_old_data) {
            typename ChannelElement<T>::shared_ptr new_input =
                find_if(pred, copy_old_data);

            if (new_input)
            {
                // We don't clear the current channel (to get it to NoData state), because there is a race
                // between find_if and this line. We have to accept (in other parts of the code) that eventually,
                // all channels return 'OldData'.
                last = new_input.get();
            }
        }

        template<typename Pred>
        typename ChannelElement<T>::shared_ptr find_if(Pred pred, bool copy_old_data) {
            typename ChannelElement<T>::shared_ptr current = currentInput();

            // We only copy OldData in the initial read of the current channel.
            // if it has no new data, the search over the other channels starts,
            // but no old data is needed.
            if ( current )
                if ( pred( copy_old_data, current ) )
                    return current;

            for (Inputs::iterator it = inputs.begin(); it != inputs.end(); ++it) {
                if (*it == current) continue;
                typename ChannelElement<T>::shared_ptr input = (*it)->narrow<T>();
                assert(input);
                if ( pred(false, input) == true)
                    return input;
            }

            return typename ChannelElement<T>::shared_ptr();
        }

    protected:
        virtual void removeInput(ChannelElementBase::shared_ptr const& input)
        {
            if (last == input) last = 0;
            MultipleInputsChannelElementBase::removeInput(input);
        }

    private:
        ChannelElement<T> *last;
    };

    template<typename T>
    class MultipleOutputsChannelElement : virtual public MultipleOutputsChannelElementBase, virtual public ChannelElement<T>
    {
    public:
        typedef boost::intrusive_ptr< MultipleInputsChannelElement<T> > shared_ptr;
        typedef typename ChannelElement<T>::value_t value_t;
        typedef typename ChannelElement<T>::param_t param_t;
        typedef typename ChannelElement<T>::reference_t reference_t;

        virtual WriteStatus data_sample(param_t sample, bool reset = true)
        {
            WriteStatus result = WriteSuccess;
            bool at_least_one_output_is_disconnected = false;
            bool at_least_one_output_is_connected = false;

            {
                RTT::os::SharedMutexLock lock(outputs_lock);
                if (outputs.empty()) return WriteSuccess;
                for(Outputs::iterator it = outputs.begin(); it != outputs.end(); ++it)
                {
                    typename ChannelElement<T>::shared_ptr output = it->channel->narrow<T>();
                    WriteStatus fs = output->data_sample(sample, reset);
                    if (result < fs) result = fs;
                    if (fs == NotConnected) {
                        it->disconnected = true;
                        at_least_one_output_is_disconnected = true;
                    } else {
                        at_least_one_output_is_connected = true;
                    }
                }
            }

            if (at_least_one_output_is_disconnected) {
                removeDisconnectedOutputs();
                if (!at_least_one_output_is_connected) result = NotConnected;
            }

            return result;
        }

        virtual WriteStatus write(param_t sample)
        {
            WriteStatus result = WriteSuccess;
            bool at_least_one_output_is_disconnected = false;
            bool at_least_one_output_is_connected = false;

            {
                RTT::os::SharedMutexLock lock(outputs_lock);
                if (outputs.empty()) return NotConnected;
                for(Outputs::iterator it = outputs.begin(); it != outputs.end(); ++it)
                {
                    typename ChannelElement<T>::shared_ptr output = it->channel->narrow<T>();
                    WriteStatus fs = output->write(sample);
                    if (it->mandatory && (result < fs)) result = fs;
                    if (fs == NotConnected) {
                        it->disconnected = true;
                        at_least_one_output_is_disconnected = true;
                    } else {
                        at_least_one_output_is_connected = true;
                    }
                }
            }

            if (at_least_one_output_is_disconnected) {
                removeDisconnectedOutputs();
                if (!at_least_one_output_is_connected) result = NotConnected;
            }

            return result;
        }
    };

    template<typename T>
    class MultipleInputsMultipleOutputsChannelElement : public MultipleInputsMultipleOutputsChannelElementBase, public MultipleInputsChannelElement<T>, public MultipleOutputsChannelElement<T>
    {
    public:
        typedef boost::intrusive_ptr< MultipleInputsMultipleOutputsChannelElement<T> > shared_ptr;
        typedef typename ChannelElement<T>::value_t value_t;
        typedef typename ChannelElement<T>::param_t param_t;
        typedef typename ChannelElement<T>::reference_t referene_t;

        using MultipleInputsChannelElement<T>::data_sample;
        using MultipleOutputsChannelElement<T>::data_sample;

        using MultipleInputsMultipleOutputsChannelElementBase::disconnect;
    };
}}

#endif