A connection policy object describes how a given connection should behave. More...

#include <rtt/ConnPolicy.hpp>

Classes
struct	ConnPolicyDefault

Public Member Functions
	ConnPolicy ()
	Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default(). More...

	ConnPolicy (int type)
	Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default(), but overrides the type. More...

	ConnPolicy (int type, int lock_policy)
	Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default(), but overrides the type and lock_policy. More...

Static Public Member Functions
static ConnPolicy &	Default ()
	Returns the process-wide default ConnPolicy that serves as a template for new ConnPolicy instances. More...

static ConnPolicy	buffer (int size, int lock_policy=LOCK_FREE, bool init_connection=false, bool pull=false)
	Create a policy for a (lock-free) fifo buffer connection of a given size. More...

static ConnPolicy	circularBuffer (int size, int lock_policy=LOCK_FREE, bool init_connection=false, bool pull=false)
	Create a policy for a (lock-free) circular fifo buffer connection of a given size. More...

static ConnPolicy	data (int lock_policy=LOCK_FREE, bool init_connection=true, bool pull=false)
	Create a policy for a (lock-free) shared data connection of a given size. More...

Public Attributes
int	type
	DATA, BUFFER or CIRCULAR_BUFFER. More...

int	size
	If the connection is a buffered connection, the size of the buffer. More...

int	lock_policy
	This is the locking policy on the connection. More...

bool	init
	If true, one should initialize the connection's value with the last value written on the writer port. More...

bool	pull
	If true, then the sink will have to pull data. More...

int	buffer_policy
	The policy on how buffer elements will be installed for this connection, which influences the behavior of reads and writes if the port has muliple connections. More...

int	max_threads
	The maximum number of threads that will access the connection data or buffer object. More...

bool	mandatory
	Whether the connection described by this connection policy is mandatory, which means that write operations will fail if the connection could not be served, e.g. More...

int	transport
	The prefered transport used. More...

int	data_size
	Suggest the payload size of the data sent over this channel. More...

std::string	name_id
	The name of this connection. More...

Static Public Attributes
static const int	UNBUFFERED = -1

static const int	DATA = 0

static const int	BUFFER = 1

static const int	CIRCULAR_BUFFER = 2

static const int	UNSYNC = 0

static const int	LOCKED = 1

static const int	LOCK_FREE = 2

static const bool	PUSH = false

static const bool	PULL = true

Detailed Description

A connection policy object describes how a given connection should behave.

Various parameters are available:

the connection type: DATA, BUFFER, CIRCULAR_BUFFER or UNBUFFERED. On a data connection, the reader will have only access to the last written value. On a buffered connection, a size number of elements can be stored until the reader reads them. BUFFER drops newer samples on full, CIRCULAR_BUFFER drops older samples on full. UNBUFFERED is only valid for output streaming connections.
the locking policy: LOCKED, LOCK_FREE or UNSYNC. This defines how locking is done in the connection. For now, only three policies are available. LOCKED uses mutexes, LOCK_FREE uses a lock free method and UNSYNC means there's no synchronisation at all (not thread safe). The latter should be used only when there is no contention (simultaneous write-read).
if, upon connection, the last value that has been written on the writer end should be written on the connection as well to initialize it. This flag has an effect only if the writer has keepsLastWrittenValue() set to true (see OutputPortInterface::keepLastWrittenValue()).
if the data is pushed or pulled on the connection. This has an effect only on multi-process communication. In the pushed case (the default), new data is actively pushed to the reader's process. In the pulled case, data must be requested by the reader.
the buffer policy, which controls how multiple connections to the same input or output port are handled in case of concurrent or subsequent read and write operations. See BufferPolicy to see all available options. Not all combinations of buffer policies and the pull flag are valid and non-standard transports can have additional restrictions.
if the connection is mandatory. Mandatory connections will let the write() call fail if the new sample cannot be successfully written. Default connections are not mandatory.
the transport type. Can be used to force a certain kind of transports. The number is a RTT transport id. When the transport type is zero, local in-process communication is used, unless one of the ports is remote. If the transport type deviates from the default remote transport of one of the ports, an out-of-band transport is setup using that type.
the data size. Some protocols require a hint on big the data will be, especially if the data is dynamically sized (like std::vector<double>). If you leave this empty (recommended), the protocol will try to guess it. The unit of data size is protocol dependent.
the name of the connection. Can be used to coordinate out of band transport such that they can find each other by name. In practice, the name contains a port number or file descriptor to be opened. You only need to provide a name_id if you're using out-of-band transports without supervisor, for example, when using MQueues without Corba.

Definition at line 107 of file ConnPolicy.hpp.

Constructor & Destructor Documentation

RTT::ConnPolicy::ConnPolicy ( )

Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default().

Definition at line 109 of file ConnPolicy.cpp.

RTT::ConnPolicy::ConnPolicy ( int type )

explicit

Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default(), but overrides the type.

You should not use this contructor anymore and prefer the static methods ConnPolicy::data(), ConnPolicy::buffer(), etc. instead.

Parameters

type

Deprecated:

Definition at line 122 of file ConnPolicy.cpp.

RTT::ConnPolicy::ConnPolicy	(	int	type,
		int	lock_policy
	)

explicit

Constructs a new ConnPolicy instance based on the current default settings as returned by ConnPolicy::Default(), but overrides the type and lock_policy.

You should not use this contructor anymore and prefer the static methods ConnPolicy::data(), ConnPolicy::buffer(), etc. instead.

Parameters

type
lock_policy

Deprecated:

Definition at line 135 of file ConnPolicy.cpp.

Member Function Documentation

ConnPolicy RTT::ConnPolicy::buffer	(	int	size,
		int	lock_policy = `LOCK_FREE`,
		bool	init_connection = `false`,
		bool	pull = `false`
	)

static

Create a policy for a (lock-free) fifo buffer connection of a given size.

Parameters

size	The size of the buffer in this connection
lock_policy	The locking policy
init_connection	If an initial sample should be pushed into the buffer upon creation.
pull	In inter-process cases, should the consumer pull itself ?

Returns: the specified policy.

Definition at line 77 of file ConnPolicy.cpp.

References init, lock_policy, pull, size, and type.

Referenced by RTT::base::OutputPortInterface::createBufferConnection().

ConnPolicy RTT::ConnPolicy::circularBuffer	(	int	size,
		int	lock_policy = `LOCK_FREE`,
		bool	init_connection = `false`,
		bool	pull = `false`
	)

static

Create a policy for a (lock-free) circular fifo buffer connection of a given size.

Parameters

size	The size of the buffer in this connection
lock_policy	The locking policy
init_connection	If an initial sample should be pushed into the buffer upon creation.
pull	In inter-process cases, should the consumer pull itself ?

Returns: the specified policy.

Definition at line 88 of file ConnPolicy.cpp.

References init, lock_policy, pull, size, and type.

ConnPolicy RTT::ConnPolicy::data	(	int	lock_policy = `LOCK_FREE`,
		bool	init_connection = `true`,
		bool	pull = `false`
	)

static

Create a policy for a (lock-free) shared data connection of a given size.

Parameters

lock_policy	The locking policy
init_connection	If the data object should be initialised with the last value of the OutputPort upon creation.
pull	In inter-process cases, should the consumer pull data itself ?

Returns: the specified policy.

Definition at line 99 of file ConnPolicy.cpp.

References init, lock_policy, pull, and type.

Referenced by RTT::base::OutputPortInterface::createDataConnection().

ConnPolicy & RTT::ConnPolicy::Default ( )

static

Returns the process-wide default ConnPolicy that serves as a template for new ConnPolicy instances.

This method returns a non-const reference and you can change the defaults. This is not thread-safe and should only be done very early in the deployment phase, before the first component is loaded and before connecting ports.

Definition at line 71 of file ConnPolicy.cpp.

Referenced by RTT::types::RealTimeTypekitPlugin::loadGlobals().

Member Data Documentation

const int RTT::ConnPolicy::BUFFER = 1

static

Definition at line 112 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildDataStorage(), RTT::types::RealTimeTypekitPlugin::loadGlobals(), RTT::operator<<(), and RTT::internal::SharedConnectionBase::SharedConnectionBase().

int RTT::ConnPolicy::buffer_policy

The policy on how buffer elements will be installed for this connection, which influences the behavior of reads and writes if the port has muliple connections.

See BufferPolicy enum for possible options.

Definition at line 216 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildChannelInput(), RTT::internal::ConnFactory::buildChannelOutput(), RTT::internal::ConnFactory::createAndCheckSharedConnection(), RTT::internal::ConnFactory::createConnection(), RTT::corba::CDataFlowInterface_i::deregisterChannel(), RTT::operator<<(), RTT::internal::ChannelBufferElement< T >::read(), boost::serialization::serialize(), RTT::internal::SharedConnection< T >::SharedConnection(), toCORBA(), and toRTT().

const int RTT::ConnPolicy::CIRCULAR_BUFFER = 2

static

Definition at line 113 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildDataStorage(), RTT::types::RealTimeTypekitPlugin::loadGlobals(), and RTT::operator<<().

const int RTT::ConnPolicy::DATA = 0

static

Definition at line 111 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildDataStorage(), RTT::types::RealTimeTypekitPlugin::loadGlobals(), RTT::operator<<(), and RTT::internal::SharedConnectionBase::SharedConnectionBase().

int RTT::ConnPolicy::data_size

mutable

Suggest the payload size of the data sent over this channel.

Connections can use this value to optimize transmission or prepare the communication channel for real-time communication. This value might be overruled by the transport protocol if it can make a better guess. The interpretation of data_size is transport specific. It may be bytes, it may be something else. Leave this value set to zero, unless the transport documents otherwise.

Definition at line 248 of file ConnPolicy.hpp.

Referenced by RTT::corba::RemoteInputPort::buildRemoteChannelOutput(), RTT::internal::ConnFactory::createAndCheckStream(), RTT::corba::RemoteOutputPort::createConnection(), RTT::corba::RemoteInputPort::createConnection(), boost::serialization::serialize(), RTT::mqueue::MQSendRecv::setupStream(), toCORBA(), and toRTT().

bool RTT::ConnPolicy::init

If true, one should initialize the connection's value with the last value written on the writer port.

This is only possible if the writer port has the keepsLastWrittenValue() flag set (i.e. if it remembers what was the last written value).

Definition at line 203 of file ConnPolicy.hpp.

Referenced by buffer(), circularBuffer(), data(), boost::serialization::serialize(), toCORBA(), and toRTT().

const int RTT::ConnPolicy::LOCK_FREE = 2

static

Definition at line 117 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildDataStorage(), RTT::types::RealTimeTypekitPlugin::loadGlobals(), and RTT::operator<<().

int RTT::ConnPolicy::lock_policy

This is the locking policy on the connection.

Definition at line 196 of file ConnPolicy.hpp.

Referenced by buffer(), RTT::internal::ConnFactory::buildChannelInput(), RTT::internal::ConnFactory::buildChannelOutput(), RTT::internal::ConnFactory::buildDataStorage(), circularBuffer(), RTT::internal::ConnFactory::createAndCheckSharedConnection(), data(), RTT::operator<<(), boost::serialization::serialize(), toCORBA(), and toRTT().

const int RTT::ConnPolicy::LOCKED = 1

static

Definition at line 116 of file ConnPolicy.hpp.

Referenced by RTT::internal::ConnFactory::buildDataStorage(), RTT::types::RealTimeTypekitPlugin::loadGlobals(), and RTT::operator<<().

bool RTT::ConnPolicy::mandatory

Whether the connection described by this connection policy is mandatory, which means that write operations will fail if the connection could not be served, e.g.

due to a full input buffer or because of a broken remote connection. By default, all connections are mandatory.

Definition at line 232 of file ConnPolicy.hpp.

Referenced by RTT::corba::RemoteInputPort::buildRemoteChannelOutput(), RTT::internal::ConnFactory::buildSharedConnection(), RTT::internal::ConnFactory::createAndCheckConnection(), RTT::internal::ConnFactory::createAndCheckSharedConnection(), RTT::internal::ConnFactory::createAndCheckStream(), RTT::corba::CDataFlowInterface_i::deregisterChannel(), boost::serialization::serialize(), toCORBA(), and toRTT().

int RTT::ConnPolicy::max_threads

The maximum number of threads that will access the connection data or buffer object.

This only needs to be specified for lock-free data structures. If 0, the number of threads will be determined by a simple heuristic depending on the read and write policies of the connection.

Definition at line 224 of file ConnPolicy.hpp.

Referenced by RTT::operator<<(), RTT::base::DataObjectBase::Options::Options(), RTT::base::BufferBase::Options::Options(), toCORBA(), and toRTT().

std::string RTT::ConnPolicy::name_id

mutable

The name of this connection.

May be used by transports to define a 'topic' or lookup name to connect two data streams. If you leave this empty (recommended), the protocol will choose an appropriate name itself. Only specify a name to work around name clashes or if the transport protocol documents to do so.

Definition at line 256 of file ConnPolicy.hpp.

Referenced by RTT::corba::RemoteInputPort::buildRemoteChannelOutput(), RTT::internal::ConnFactory::createAndCheckSharedConnection(), RTT::internal::ConnFactory::createAndCheckStream(), RTT::corba::RemoteOutputPort::createConnection(), RTT::corba::RemoteInputPort::createConnection(), RTT::internal::ConnFactory::createOutOfBandConnection(), RTT::internal::ConnFactory::createStream(), RTT::corba::CDataFlowInterface_i::deregisterChannel(), RTT::internal::ConnFactory::findSharedConnection(), RTT::internal::SharedConnectionBase::getName(), RTT::operator<<(), boost::serialization::serialize(), RTT::mqueue::MQSendRecv::setupStream(), RTT::internal::SharedConnectionBase::SharedConnectionBase(), toCORBA(), and toRTT().