Implements the a ChannelElement using message queues. More...

#include <rtt/transports/mqueue/MQChannelElement.hpp>

Inheritance diagram for RTT::mqueue::MQChannelElement< T >:

Public Types
typedef T	value_t
typedef boost::intrusive_ptr < ChannelElement< T > >	shared_ptr
typedef boost::call_traits< T > ::param_type	param_t
typedef boost::call_traits< T > ::reference	reference_t
Public Member Functions
	MQChannelElement (base::PortInterface *port, types::TypeMarshaller const &transport, const ConnPolicy &policy, bool is_sender)
	Create a channel element for remote data exchange.
virtual bool	inputReady ()
	This is called by an input port when it is ready to receive data.
virtual bool	data_sample (typename base::ChannelElement< T >::param_t sample)
bool	signal ()
	Signal will cause a read-write cycle to transfer the data from the data/buffer element to the message queue and vice versa.
FlowStatus	read (typename base::ChannelElement< T >::reference_t sample, bool copy_old_data)
	Read from the message queue.
bool	write (typename base::ChannelElement< T >::param_t sample)
	Write to the message queue.
shared_ptr	getOutput ()
	Returns the next channel element in the channel's propagation direction.
shared_ptr	getInput ()
	Returns the current input channel element.
virtual bool	data_sample (param_t sample)
	Provides a data sample to initialize this connection.
virtual value_t	data_sample ()
virtual bool	write (param_t sample)
	Writes a new sample on this connection.
virtual FlowStatus	read (reference_t sample, bool copy_old_data)
	Reads a sample from the connection.
void	removeInput ()
	Removes the input channel (if any).
ChannelElementBase::shared_ptr	getInputEndPoint ()
	Returns the first input channel element of this connection.
ChannelElementBase::shared_ptr	getOutputEndPoint ()
	Returns the last output channel element of this connection.
void	setOutput (shared_ptr output)
	Sets the output of this channel element to output and sets the input of output to this.
virtual void	clear ()
	Clears any data stored by the channel.
virtual void	disconnect (bool forward)
	Performs a disconnection of this channel's endpoints.
virtual PortInterface *	getPort () const
	Gets the port this channel element is connected to.
void	setupStream (base::DataSourceBase::shared_ptr ds, base::PortInterface *port, ConnPolicy const &policy, bool is_sender)
void	cleanupStream ()
virtual void	mqNewSample (base::DataSourceBase::shared_ptr ds)
	Adapts the mq send/receive buffer size according to the data in mqdata_source, or the value set in mdata_size;.
virtual bool	mqReady (base::DataSourceBase::shared_ptr ds, base::ChannelElementBase *chan)
	Works only in receive mode, waits for a new sample and adapts the receive buffer to match it's size.
bool	mqRead (base::DataSourceBase::shared_ptr ds)
	Read from the message queue.
bool	mqWrite (base::DataSourceBase::shared_ptr ds)
	Write to the message queue.
Protected Member Functions
void	ref ()
	Increases the reference count.
void	deref ()
	Decreases the reference count, and deletes the object if it is zero.
Protected Attributes
types::TypeMarshaller const &	mtransport
	Transport marshaller used for size calculations and data updates.
void *	marshaller_cookie
	A private blob that is returned by mtransport.getCookie().
mqd_t	mqdes
	MQueue file descriptor.
char *	buf
	Send/Receive buffer.
bool	mis_sender
	True if this object is a sender.
bool	minit_done
	True if setupStream() was called, false after cleanupStream().
int	max_size
	The size of buf.
std::string	mqname
	The name of the queue, as specified in the ConnPolicy when creating the stream, or self-calculated when that name was empty.
int	mdata_size
	The size of the data, as specified in the ConnPolicy when creating the stream, or calculated using the transport when that size was zero.

Detailed Description

template<typename T>
class RTT::mqueue::MQChannelElement< T >

Implements the a ChannelElement using message queues.

It converts the C++ calls into MQ messages and vice versa.

Todo:

This class can be refactored into a base class with generic mqueue code and a subclass with type specific info.

This is an inspiration for a generic, transport independent channel element.

Definition at line 62 of file MQChannelElement.hpp.

Constructor & Destructor Documentation

template<typename T>

RTT::mqueue::MQChannelElement< T >::MQChannelElement	(	base::PortInterface *	port,
		types::TypeMarshaller const &	transport,
		const ConnPolicy &	policy,
		bool	is_sender
	)		`[inline]`

Create a channel element for remote data exchange.

Parameters:

transport The type specific object that will be used to marshal the data.

Definition at line 74 of file MQChannelElement.hpp.

Member Function Documentation

void ChannelElementBase::clear ( ) [virtual, inherited]

Clears any data stored by the channel.

It means that ChannelElement::read() will return false afterwards (provided that no new data has been written on the meantime of course)

By default, the channel element forwards the calls to its input

Reimplemented in RTT::internal::ChannelBufferElement< T >, and RTT::internal::ChannelDataElement< T >.

Definition at line 116 of file ChannelInterface.cpp.

References RTT::base::ChannelElementBase::getInput().

template<typename T>

virtual bool RTT::base::ChannelElement< T >::data_sample ( param_t sample ) [inline, virtual, inherited]

Provides a data sample to initialize this connection.

This is used before the first write() in order to inform this connection of the size of the data. As such enough storage space can be allocated before the actual writing begins.

Returns:: false if an error occured that requires the channel to be invalidated.

Reimplemented in RTT::internal::ChannelBufferElement< T >, and RTT::internal::ChannelDataElement< T >.

Definition at line 82 of file ChannelElement.hpp.

References RTT::base::ChannelElement< T >::data_sample(), and RTT::base::ChannelElement< T >::getOutput().

Referenced by RTT::base::ChannelElement< T >::data_sample(), RTT::InputPort< T >::getDataSample(), and RTT::mqueue::MQChannelElement< T >::inputReady().

void ChannelElementBase::disconnect ( bool forward ) [virtual, inherited]

Performs a disconnection of this channel's endpoints.

If forward is true, then the disconnection is initiated by the input endpoint. Otherwise, it has been initiated by the output endpoint.

Reimplemented in RTT::corba::RemoteChannelElement< T >, RTT::internal::ConnOutputEndpoint< T >, and RTT::internal::ConnInputEndpoint< T >.

Definition at line 75 of file ChannelInterface.cpp.

References RTT::base::ChannelElementBase::getInput(), and RTT::base::ChannelElementBase::getOutput().

template<typename T>

shared_ptr RTT::base::ChannelElement< T >::getInput ( ) [inline, inherited]

Returns the current input channel element.

This will only return a valid channel element if another element has received this object as an argument to setOutput().

Returns:

Reimplemented from RTT::base::ChannelElementBase.

Definition at line 68 of file ChannelElement.hpp.

Referenced by RTT::corba::RemoteChannelElement< T >::inputReady(), RTT::base::ChannelElement< T >::read(), and RTT::mqueue::MQChannelElement< T >::signal().

ChannelElementBase::shared_ptr ChannelElementBase::getInputEndPoint ( ) [inherited]

Returns the first input channel element of this connection.

Will return the channel element the furthest away from the input port, or this if none.

Returns:: getInput() ? getInput()->getInputEndPoint() : this

Definition at line 96 of file ChannelInterface.cpp.

References RTT::base::ChannelElementBase::getInput().

ChannelElementBase::shared_ptr ChannelElementBase::getOutputEndPoint ( ) [inherited]

Returns the last output channel element of this connection.

Will return the channel element the furthest away from the output port, or this if none.

Returns:: getOutput() ? getOutput()->getInputEndPoint() : this

Definition at line 101 of file ChannelInterface.cpp.

References RTT::base::ChannelElementBase::getOutput().

PortInterface * ChannelElementBase::getPort ( ) const [virtual, inherited]

Gets the port this channel element is connected to.

Returns:: null if no port is connected to this element, the port (or a proxy representing the port) otherwise.

Reimplemented in RTT::internal::ConnOutputEndpoint< T >, and RTT::internal::ConnInputEndpoint< T >.

Definition at line 131 of file ChannelInterface.cpp.

template<typename T>

virtual bool RTT::mqueue::MQChannelElement< T >::inputReady ( ) [inline, virtual]

This is called by an input port when it is ready to receive data.

Each channel element has the responsibility to pass this notification on to the next, in the direction of the output.

Returns:: false if a fatal connection failure was encountered and the channel needs to be destroyed.

Reimplemented from RTT::base::ChannelElementBase.

Definition at line 89 of file MQChannelElement.hpp.

References RTT::base::ChannelElement< T >::data_sample(), RTT::base::ChannelElement< T >::getOutput(), and RTT::mqueue::MQSendRecv::mqReady().

void MQSendRecv::mqNewSample ( base::DataSourceBase::shared_ptr ds ) [virtual, inherited]

Adapts the mq send/receive buffer size according to the data in mqdata_source, or the value set in mdata_size;.

Parameters:

sample

Definition at line 181 of file MQSendRecv.cpp.

References RTT::mqueue::MQSendRecv::buf, RTT::types::TypeMarshaller::getSampleSize(), RTT::mqueue::MQSendRecv::max_size, RTT::mqueue::MQSendRecv::mdata_size, and RTT::mqueue::MQSendRecv::mtransport.

bool MQSendRecv::mqRead ( base::DataSourceBase::shared_ptr ds ) [inherited]

Read from the message queue.

Parameters:

sample stores the resulting data sample.

Returns:: true if an item could be read.

Definition at line 239 of file MQSendRecv.cpp.

References RTT::mqueue::MQSendRecv::buf, RTT::mqueue::MQSendRecv::marshaller_cookie, RTT::mqueue::MQSendRecv::max_size, RTT::mqueue::MQSendRecv::mqdes, RTT::mqueue::MQSendRecv::mtransport, and RTT::types::TypeMarshaller::updateFromBlob().

Referenced by RTT::mqueue::MQChannelElement< T >::signal().

bool MQSendRecv::mqReady	(	base::DataSourceBase::shared_ptr	ds,
		base::ChannelElementBase *	chan
	)		`[virtual, inherited]`

Works only in receive mode, waits for a new sample and adapts the receive buffer to match it's size.

Returns:

Definition at line 191 of file MQSendRecv.cpp.

References RTT::mqueue::MQSendRecv::buf, RTT::mqueue::MQSendRecv::marshaller_cookie, RTT::mqueue::MQSendRecv::max_size, RTT::mqueue::MQSendRecv::minit_done, RTT::mqueue::MQSendRecv::mis_sender, RTT::mqueue::MQSendRecv::mqdes, RTT::mqueue::MQSendRecv::mtransport, and RTT::types::TypeMarshaller::updateFromBlob().

Referenced by RTT::mqueue::MQChannelElement< T >::inputReady().

bool MQSendRecv::mqWrite ( base::DataSourceBase::shared_ptr ds ) [inherited]

Write to the message queue.

Parameters:

ds	the data sample to write
is_data_sample	true if the sample is used for initialization, false if it is a proper write

Returns:: true if it could be sent.

Definition at line 254 of file MQSendRecv.cpp.

References RTT::mqueue::MQSendRecv::buf, RTT::types::TypeMarshaller::fillBlob(), RTT::mqueue::MQSendRecv::marshaller_cookie, RTT::mqueue::MQSendRecv::max_size, RTT::mqueue::MQSendRecv::mqdes, and RTT::mqueue::MQSendRecv::mtransport.

Referenced by RTT::mqueue::MQChannelElement< T >::write().

template<typename T>

virtual FlowStatus RTT::base::ChannelElement< T >::read	(	reference_t	sample,
		bool	copy_old_data
	)		`[inline, virtual, inherited]`

Reads a sample from the connection.

sample is a reference which will get updated if a sample is available. The method returns true if a sample was available, and false otherwise. If false is returned, then sample is not modified by the method

Reimplemented in RTT::internal::ChannelBufferElement< T >, and RTT::internal::ChannelDataElement< T >.

Definition at line 116 of file ChannelElement.hpp.

References RTT::base::ChannelElement< T >::getInput(), and RTT::base::ChannelElement< T >::read().

Referenced by RTT::base::ChannelElement< T >::read(), and RTT::mqueue::MQChannelElement< T >::signal().

template<typename T>

FlowStatus RTT::mqueue::MQChannelElement< T >::read	(	typename base::ChannelElement< T >::reference_t	sample,
		bool	copy_old_data
	)		`[inline]`

Read from the message queue.

Parameters:

sample stores the resulting data sample.

Returns:: true if an item could be read.

Definition at line 156 of file MQChannelElement.hpp.

void RTT::base::ChannelElementBase::removeInput ( ) [inherited]

Removes the input channel (if any).

This call may delete channels from memory.

void ChannelElementBase::setOutput ( shared_ptr output ) [inherited]

Sets the output of this channel element to output and sets the input of output to this.

This implies that this channel element becomes the input of output. There is no setInput function since this function does both setting input and output of this and output.

Parameters:

output the next element in chain.

Definition at line 68 of file ChannelInterface.cpp.

Referenced by RTT::internal::ConnFactory::buildBufferedChannelInput(), RTT::internal::ConnFactory::buildBufferedChannelOutput(), and RTT::internal::ConnFactory::buildChannelInput().

template<typename T>

bool RTT::mqueue::MQChannelElement< T >::signal ( ) [inline, virtual]

Signal will cause a read-write cycle to transfer the data from the data/buffer element to the message queue and vice versa.

Note: this virtual function is a bit abused. For a sending MQ, signal triggers a direct read on the data element. For a receiving MQ, signal is used by the dispatcher thread to provoque a read from the MQ and forward it to the next channel element.

In the sending case, signal could trigger a dispatcher thread that does the read/write cycle, but that seems only causing overhead. The receiving case must use a thread which blocks on all mq file descriptors.

Returns:: true in case the forwarding could be done, false otherwise.

Reimplemented from RTT::base::ChannelElementBase.

Definition at line 132 of file MQChannelElement.hpp.

References RTT::base::ChannelElement< T >::getInput(), RTT::base::ChannelElement< T >::getOutput(), RTT::mqueue::MQSendRecv::mis_sender, RTT::mqueue::MQSendRecv::mqRead(), RTT::base::ChannelElement< T >::read(), RTT::base::ChannelElement< T >::write(), and RTT::mqueue::MQChannelElement< T >::write().

template<typename T>

virtual bool RTT::base::ChannelElement< T >::write ( param_t sample ) [inline, virtual, inherited]

Writes a new sample on this connection.

sample is the sample to write.

Returns:: false if an error occured that requires the channel to be invalidated. In no ways it indicates that the sample has been received by the other side of the channel.

Reimplemented in RTT::internal::ChannelBufferElement< T >, and RTT::internal::ChannelDataElement< T >.

Definition at line 103 of file ChannelElement.hpp.

References RTT::base::ChannelElement< T >::getOutput(), and RTT::base::ChannelElement< T >::write().

Referenced by RTT::mqueue::MQChannelElement< T >::signal(), and RTT::base::ChannelElement< T >::write().

template<typename T>

bool RTT::mqueue::MQChannelElement< T >::write ( typename base::ChannelElement< T >::param_t sample ) [inline]