This DataObject is a Lock-Free implementation, such that reads and writes can happen concurrently without priority inversions. More...

#include <DataObjectLockFree.hpp>

Inheritance diagram for RTT::base::DataObjectLockFree< T >:

[legend]

Classes
struct	DataBuf

Public Types
typedef DataObjectBase::Options	Options

typedef DataObjectInterface< T >::param_t	param_t

typedef DataObjectInterface< T >::reference_t	reference_t

typedef DataObjectInterface< T >::value_t	value_t

Public Types inherited from RTT::base::DataObjectInterface< T >
typedef boost::call_traits< T >::param_type	param_t

typedef boost::call_traits< T >::reference	reference_t

typedef boost::shared_ptr< DataObjectInterface< T > >	shared_ptr

typedef T	value_t

Public Member Functions
virtual void	clear ()

virtual bool	data_sample (param_t sample, bool reset=true)

virtual value_t	data_sample () const

	DataObjectLockFree (const Options &options=Options())

	DataObjectLockFree (param_t initial_value, const Options &options=Options())

virtual value_t	Get () const

virtual FlowStatus	Get (reference_t pull, bool copy_old_data, bool copy_sample) const

virtual FlowStatus	Get (reference_t pull, bool copy_old_data=true) const

virtual bool	Set (param_t push)

	~DataObjectLockFree ()

Public Member Functions inherited from RTT::base::DataObjectInterface< T >
	DataObjectInterface ()

virtual	~DataObjectInterface ()

Public Member Functions inherited from RTT::base::DataObjectBase
virtual	~DataObjectBase ()

Public Attributes
const unsigned int	MAX_THREADS
	The maximum number of threads. More...

Private Types
typedef DataBuf *	PtrType

typedef DataBuf	ValueType

typedef DataBuf *volatile	VolPtrType

Private Attributes
const unsigned int	BUF_LEN

DataBuf *	data

bool	initialized

VolPtrType	read_ptr

VolPtrType	write_ptr

Detailed Description

template<class T>
class RTT::base::DataObjectLockFree< T >

This DataObject is a Lock-Free implementation, such that reads and writes can happen concurrently without priority inversions.

When there are more writes than reads, the last write will be returned. The internal buffer can get full if too many concurrent reads are taking to long. In that case, each new read will read the element the previous read returned.

* The following Truth table applies when a Low Priority thread is
* preempted by a High Priority thread :
*
*   L\H | Set | Get |
*   Set | Ok  | Ok  |
*   Get | Ok  | Ok  |
*
* legend : L : Low Priority thread
*          H : High Priority thread
*          Blk: Blocks High Priority thread (bad!)
*          internal::NA : Not allowed !
*

Further, multiple reads may occur before, during and after a write operation simultaneously. The buffer needs readers+2*writers elements to be guaranteed non blocking.

Definition at line 80 of file DataObjectLockFree.hpp.

Member Typedef Documentation

template<class T>

typedef DataObjectBase::Options RTT::base::DataObjectLockFree< T >::Options

Definition at line 88 of file DataObjectLockFree.hpp.

template<class T>

typedef DataObjectInterface<T>::param_t RTT::base::DataObjectLockFree< T >::param_t

Definition at line 86 of file DataObjectLockFree.hpp.

template<class T>

typedef DataBuf* RTT::base::DataObjectLockFree< T >::PtrType

private

Definition at line 123 of file DataObjectLockFree.hpp.

template<class T>

typedef DataObjectInterface<T>::reference_t RTT::base::DataObjectLockFree< T >::reference_t

Definition at line 85 of file DataObjectLockFree.hpp.

template<class T>

typedef DataObjectInterface<T>::value_t RTT::base::DataObjectLockFree< T >::value_t

Definition at line 84 of file DataObjectLockFree.hpp.

template<class T>

typedef DataBuf RTT::base::DataObjectLockFree< T >::ValueType

private

Definition at line 122 of file DataObjectLockFree.hpp.

template<class T>

typedef DataBuf* volatile RTT::base::DataObjectLockFree< T >::VolPtrType

private

Definition at line 121 of file DataObjectLockFree.hpp.

Constructor & Destructor Documentation

template<class T>

RTT::base::DataObjectLockFree< T >::DataObjectLockFree ( const Options & options = Options() )

inline

Construct an uninitialized DataObjectLockFree.

Parameters

max_threads The maximum number of threads accessing this DataObject.

Definition at line 141 of file DataObjectLockFree.hpp.

template<class T>

RTT::base::DataObjectLockFree< T >::DataObjectLockFree	(	param_t	initial_value,
		const Options &	options = `Options()`
	)

inline

Construct a DataObjectLockFree.

Parameters

initial_value	The initial value of this DataObject.
max_threads	The maximum number of threads accessing this DataObject.

Note: You have to specify the maximum number of threads explicitly

Definition at line 158 of file DataObjectLockFree.hpp.

template<class T>

RTT::base::DataObjectLockFree< T >::~DataObjectLockFree ( )

inline

Definition at line 170 of file DataObjectLockFree.hpp.

Member Function Documentation

template<class T>

virtual void RTT::base::DataObjectLockFree< T >::clear ( )

inlinevirtual

Clears any data stored by this data object, so that any subsequent Get() without a new Set() will return NoData.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 337 of file DataObjectLockFree.hpp.

template<class T>

virtual bool RTT::base::DataObjectLockFree< T >::data_sample	(	param_t	sample,
		bool	reset = `true`
	)

inlinevirtual

Provides a data sample to initialize this data object. As such enough storage space can be allocated before the actual writing begins.

Parameters

sample	the data sample
reset	enforce reinitialization even if this operation clears the stored data.

Returns: true if the data object was successfully (re)initialized.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 310 of file DataObjectLockFree.hpp.

template<class T>

virtual value_t RTT::base::DataObjectLockFree< T >::data_sample ( ) const

inlinevirtual

Reads back a data sample.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 329 of file DataObjectLockFree.hpp.

template<class T>

virtual value_t RTT::base::DataObjectLockFree< T >::Get ( ) const

inlinevirtual

Get a copy of the data. This method will allocate memory twice if data is not a value type. Use Get(reference_t) for the non-allocating version.

Returns: A copy of the data.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 181 of file DataObjectLockFree.hpp.

template<class T>

virtual FlowStatus RTT::base::DataObjectLockFree< T >::Get	(	reference_t	pull,
		bool	copy_old_data,
		bool	copy_sample
	)		const

inlinevirtual

Get a copy of the Data (non allocating). If pull has reserved enough memory to store the copy, no memory will be allocated.

Parameters

pull	A copy of the data.
copy_old_data	If true, also copy the data if the data object has not been updated since the last call.
copy_sample	If true, copy the data unconditionally.

Definition at line 197 of file DataObjectLockFree.hpp.

template<class T>

virtual FlowStatus RTT::base::DataObjectLockFree< T >::Get	(	reference_t	pull,
		bool	copy_old_data = `true`
	)		const

inlinevirtual

Get a copy of the Data (non allocating). If pull has reserved enough memory to store the copy, no memory will be allocated.

Parameters

pull	A copy of the data.
copy_old_data	If true, also copy the data if the data object has not been updated since the last call.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 245 of file DataObjectLockFree.hpp.

template<class T>

virtual bool RTT::base::DataObjectLockFree< T >::Set ( param_t push )

inlinevirtual

Set the data to a certain value (non blocking).

Parameters

push	The data which must be set.

Implements RTT::base::DataObjectInterface< T >.

Definition at line 255 of file DataObjectLockFree.hpp.

Member Data Documentation

template<class T>

const unsigned int RTT::base::DataObjectLockFree< T >::BUF_LEN

private

Conversion of number of threads to size of buffer.

Definition at line 99 of file DataObjectLockFree.hpp.

template<class T>

DataBuf* RTT::base::DataObjectLockFree< T >::data

private

A 3 element Data buffer

Definition at line 131 of file DataObjectLockFree.hpp.

template<class T>

bool RTT::base::DataObjectLockFree< T >::initialized

private

Definition at line 133 of file DataObjectLockFree.hpp.

template<class T>

const unsigned int RTT::base::DataObjectLockFree< T >::MAX_THREADS

The maximum number of threads.

Definition at line 93 of file DataObjectLockFree.hpp.

template<class T>

VolPtrType RTT::base::DataObjectLockFree< T >::read_ptr

private

Definition at line 125 of file DataObjectLockFree.hpp.

template<class T>

VolPtrType RTT::base::DataObjectLockFree< T >::write_ptr

private

Definition at line 126 of file DataObjectLockFree.hpp.

The documentation for this class was generated from the following file:

DataObjectLockFree.hpp

Classes

Public Types

Public Member Functions

Public Attributes

Private Types

Private Attributes

Detailed Description

template<class T> class RTT::base::DataObjectLockFree< T >

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

template<class T>
class RTT::base::DataObjectLockFree< T >