DataObjectInterfaces.hpp

/***************************************************************************
  tag: Peter Soetens  Mon Jan 19 14:11:26 CET 2004  DataObjectInterfaces.hpp

                        DataObjectInterfaces.hpp -  description
                           -------------------
    begin                : Mon January 19 2004
    copyright            : (C) 2004 Peter Soetens
    email                : peter.soetens@mech.kuleuven.ac.be

 ***************************************************************************
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#ifndef CORELIB_DATAOBJECTINTERFACES_HPP
#define CORELIB_DATAOBJECTINTERFACES_HPP


#include "os/MutexLock.hpp"
#include "os/oro_atomic.h"
#include <string>

#include "DataSource.hpp"

namespace RTT
{

    template <class T>
    class DataObjectInterface
        : public AssignableDataSource<T>
    {
    public:
        typedef typename boost::intrusive_ptr<DataObjectInterface<T> > shared_ptr;

        DataObjectInterface() {
            this->ref();
        }

        virtual ~DataObjectInterface() {}

        typedef T DataType;

        virtual void Get( DataType& pull ) const = 0;

        virtual DataType Get() const = 0;

        virtual void Set( const DataType& push ) = 0;

        virtual const std::string& getName() const = 0;

        typename DataSource<T>::result_t value() const {
            return this->Get();
        }

        virtual typename DataSource<DataType>::result_t get() const {
            return this->Get();
        }

        virtual void set( typename AssignableDataSource<DataType>::param_t t ) {
            this->Set( t );
        }

        virtual typename AssignableDataSource<DataType>::reference_t set() {
            // return null reference, allowed by API.
            typename DataSource<DataType>::value_t* tmp = 0;
            return typename AssignableDataSource<DataType>::reference_t(*tmp);
        }

        virtual typename AssignableDataSource<DataType>::const_reference_t rvalue() const {
            // return null reference, allowed by API.
            typename DataSource<DataType>::value_t* tmp = 0;
            return typename AssignableDataSource<DataType>::const_reference_t(*tmp);
        }

    };


    template<class T>
    class DataObjectLocked
        : public DataObjectInterface<T>
    {
        mutable OS::Mutex lock;

        T data;

        std::string name;
    public:
        DataObjectLocked(const std::string& _name, const T& initial_value = T() )
            : data(initial_value), name(_name) {}

        const std::string& getName() const { return name;}

        void setName( const std::string& _name )
        {
            name = _name;
        }

        typedef T DataType;

        void Get( DataType& pull ) const { OS::MutexLock locker(lock); pull = data; }

        DataType Get() const { DataType cache;  Get(cache); return cache; }

        void Set( const DataType& push ) { OS::MutexLock locker(lock); data = push; }

        DataObjectLocked<DataType>* clone() const {
            return new DataObjectLocked<DataType>(name);
        }

        DataObjectLocked<DataType>* copy( std::map<const DataSourceBase*, DataSourceBase*>&  ) const {
            return const_cast<DataObjectLocked<DataType>*>(this);
        }
    };

    template<class T>
    class DataObjectPrioritySet
        : public DataObjectInterface<T>
    {
        mutable OS::Mutex lock;
        mutable bool dirty_flag;

        T data;
        T mcopy;

        std::string name;
    public:
        DataObjectPrioritySet(const std::string& _name, const T& initial_value = T() )
            : data(initial_value), mcopy(), name(_name) {}

        const std::string& getName() const { return name;}

        void setName( const std::string& _name )
        {
            name = _name;
        }

        typedef T DataType;

        void Get( DataType& pull ) const
        { if (dirty_flag) pull = mcopy; else {OS::MutexLock locker(lock); pull = data;} }

        DataType Get() const { DataType cache; Get(cache); return cache; }

        void Set( const DataType& push )
        {
            OS::MutexTryLock locker(lock);
            if (locker.isSuccessful())
                {data = push; dirty_flag = false;}
            else
                {mcopy = push; dirty_flag = true;}
        }

        DataObjectPrioritySet<DataType>* clone() const {
            return new DataObjectPrioritySet<DataType>(name);
        }

        DataObjectPrioritySet<DataType>* copy( std::map<const DataSourceBase*, DataSourceBase*>&  ) const {
            return const_cast<DataObjectPrioritySet<DataType>*>(this);
        }
    };

    template<class T>
    class DataObjectPriorityGet
        : public DataObjectInterface<T>
    {
        mutable OS::Mutex lock;

        T data;
        T mcopy;

        std::string name;
    public:
        DataObjectPriorityGet(const std::string& _name, const T& initial_value = T()  )
            : data(initial_value), mcopy(), name(_name) {}

        const std::string& getName() const { return name;}

        void setName( const std::string& _name )
        {
            name = _name;
        }

        typedef T DataType;

        void Get( DataType& pull ) const
        {
            // If two low priority gets access this method,
            // while Set() is in copy,
            // the second one will pull in the copy which
            // is modified by the Set().
            OS::MutexTryLock locker(lock);
            if ( locker.isSuccessful() )
                {pull = data;}
            else
                {pull = mcopy;}
        }

        DataType Get() const { DataType cache; Get(cache); return cache; }

        void Set( const DataType& push )
        {
            {
                OS::MutexLock locker(lock);
                data = push;
            }
            mcopy = data;
        }

        DataObjectPriorityGet<DataType>* clone() const {
            return new DataObjectPriorityGet<DataType>(name);
        }

        DataObjectPriorityGet<DataType>* copy( std::map<const DataSourceBase*, DataSourceBase*>&  ) const {
            return const_cast<DataObjectPriorityGet<DataType>*>(this);
        }
    };

    template<class T>
    class DataObjectLockFree
        : public DataObjectInterface<T>
    {
    public:
        typedef T DataType;

        static const unsigned int MAX_THREADS=8;
    private:
        static const unsigned int BUF_LEN=MAX_THREADS+2;

        struct DataBuf {
            DataBuf()
                : data(), counter(), next()
            {
                oro_atomic_set(&counter, 0);
            }
            DataType data; mutable oro_atomic_t counter; DataBuf* next;
        };

        typedef DataBuf* volatile VolPtrType;
        typedef DataBuf  ValueType;
        typedef DataBuf* PtrType;

        VolPtrType read_ptr;
        VolPtrType write_ptr;

        DataBuf data[BUF_LEN];

        std::string name;

    public:

        DataObjectLockFree(const std::string& _name, const T& initial_value = T() )
            : read_ptr(&data[ 0 ]),
              write_ptr(&data[ 1 ]),
              name(_name)
        {
            // prepare the buffer.
            for (unsigned int i = 0; i < BUF_LEN-1; ++i) {
                data[i].data = initial_value;
                data[i].next = &data[i+1];
            }
            data[BUF_LEN-1].next = &data[0];
        }

        const std::string& getName() const { return name;}

        void setName( const std::string& _name )
        {
            name = _name;
        }

        DataType Get() const {DataType cache; Get(cache); return cache; }

        void Get( DataType& pull ) const
        {
            PtrType reading;
            // loop to combine Read/Modify of counter
            // This avoids a race condition where read_ptr
            // could become write_ptr ( then we would read corrupted data).
            do {
                reading = read_ptr;            // copy buffer location
                oro_atomic_inc(&reading->counter); // lock buffer, no more writes
                if ( reading != read_ptr )     // if read_ptr changed,
                    oro_atomic_dec(&reading->counter); // better to start over.
                else
                    break;
            } while ( true );
            // from here on we are sure that 'reading'
            // is a valid buffer to read from.
            pull = reading->data;               // takes some time
            oro_atomic_dec(&reading->counter);       // release buffer
        }

        void Set( const DataType& push )
        {
            // writeout in any case
            write_ptr->data = push;
            PtrType wrote_ptr = write_ptr;
            // if next field is occupied (by read_ptr or counter),
            // go to next and check again...
            while ( oro_atomic_read( &write_ptr->next->counter ) != 0 || write_ptr->next == read_ptr )
                {
                    write_ptr = write_ptr->next;
                    if (write_ptr == wrote_ptr)
                        return; // nothing found, to many readers !
                }

            // we will be able to move, so replace read_ptr
            read_ptr  = wrote_ptr;
            write_ptr = write_ptr->next; // we checked this in the while loop
        }

        DataObjectLockFree<DataType>* clone() const {
            return new DataObjectLockFree<DataType>(name);
        }

        DataObjectLockFree<DataType>* copy( std::map<const DataSourceBase*, DataSourceBase*>&  ) const {
            return const_cast<DataObjectLockFree<DataType>*>(this);
        }

    };

    template<class T>
    class DataObject
        : public DataObjectInterface<T>
    {
        T data;

        std::string name;
    public:
        DataObject(const std::string& _name, const T& initial_value = T()  )
            : data(initial_value), name(_name) {}

        const std::string& getName() const { return name;}

        void setName( const std::string& _name )
        {
            name = _name;
        }

        typedef T DataType;

        void Get( DataType& pull ) const { pull = data; }

        DataType Get() const { return data; }

        void Set( const DataType& push ) { data = push; }

        DataObject<DataType>* clone() const {
            return new DataObject<DataType>(name);
        }

        DataObject<DataType>* copy( std::map<const DataSourceBase*, DataSourceBase*>&  ) const {
            return const_cast<DataObject<DataType>*>(this);
        }

    };
}

#endif