fkie_message_filters::Sequencer< Inputs > Class Template Reference

Enforce correct temporal order. More...

#include <sequencer.h>

Inheritance diagram for fkie_message_filters::Sequencer< Inputs >:

Public Member Functions
void	flush ()
	Flush the message queue. More...
void	reset () noexcept override
	Reset filter state. More...
	Sequencer (const ros::Duration &max_delay=ros::Duration(1, 0)) noexcept
	Constructor. More...
void	set_max_delay (const ros::Duration &max_delay) noexcept
	Modify maximum delay. More...
Public Member Functions inherited from fkie_message_filters::Sink< Inputs... >
Connection	connect_to_source (Source< Inputs... > &src) noexcept
	Connect this sink to a source. More...
void	disconnect_from_all_sources () noexcept
	Disconnect from all connected sources. More...
virtual	~Sink ()
Public Member Functions inherited from fkie_message_filters::FilterBase
virtual	~FilterBase ()
Public Member Functions inherited from fkie_message_filters::Source< IO< Inputs... > >
Connection	connect_to_sink (Sink< Outputs... > &dst) noexcept
	Connect this source to a sink. More...
void	disconnect_from_all_sinks () noexcept
	Disconnect from all connected sinks. More...
virtual	~Source ()

Protected Member Functions
void	receive (const Inputs &... in) override
	Process incoming data. More...
Protected Member Functions inherited from fkie_message_filters::Source< IO< Inputs... > >
void	send (const Outputs &... out)
	Pass data to all connected sinks. More...

Private Types
using	Queue = std::multimap< ros::Time, QueueElement >
using	QueueElement = std::tuple< Inputs... >

Private Attributes
ros::Time	cutoff_
ros::Duration	max_delay_
std::mutex	mutex_
Queue	queue_

Additional Inherited Members
Public Types inherited from fkie_message_filters::Sink< Inputs... >
using	Input = IO< Inputs... >
	Grouped input types. More...
Public Types inherited from fkie_message_filters::Source< IO< Inputs... > >
using	Output = IO< Outputs... >
	Grouped output types. More...
Static Public Attributes inherited from fkie_message_filters::Sink< Inputs... >
static constexpr std::size_t	NUM_INPUTS
	Number of input arguments. More...
Static Public Attributes inherited from fkie_message_filters::Source< IO< Inputs... > >
static constexpr std::size_t	NUM_OUTPUTS
	Number of output arguments. More...

Detailed Description

template<class... Inputs>
class fkie_message_filters::Sequencer< Inputs >

Enforce correct temporal order.

This filter sorts incoming messages according to their header timestamp, and forwards them in order. It needs the expected maximum delay by which messages might arrive out of order, and forwarded messages will be out of date by at least this delay. However, all forwarded messages will be guaranteed to be in temporal order, and no message will be dropped unless it arrives with a larger delay, compared to the most recently received message.

If the filter input is not unary, only the first argument is examined, which must have an accessible ROS header as determined by the ros::message_traits template.

Definition at line 43 of file sequencer.h.

Member Typedef Documentation

Queue

template<class... Inputs>

using fkie_message_filters::Sequencer< Inputs >::Queue = std::multimap<ros::Time, QueueElement>

private

Definition at line 77 of file sequencer.h.

QueueElement

template<class... Inputs>

using fkie_message_filters::Sequencer< Inputs >::QueueElement = std::tuple<Inputs...>

private

Definition at line 76 of file sequencer.h.

Constructor & Destructor Documentation

Sequencer()

template<class... Inputs>

fkie_message_filters::Sequencer< Inputs >::Sequencer ( const ros::Duration &  max_delay = ros::Duration(1, 0) )

explicitnoexcept

Constructor.

• max_delay the maximum delay of any message

Definition at line 34 of file sequencer_impl.h.

Member Function Documentation

flush()

template<class... Inputs>

void fkie_message_filters::Sequencer< Inputs >::flush

(

)

Flush the message queue.

This will forward all messages in the queue, regardless of their age. Afterwards, new messages which are older than the most recently forwarded one will be dropped, even if their delay is smaller than the configured threshold. In other words, a call to this method will never violate the temporal order constraint.

Definition at line 71 of file sequencer_impl.h.

receive()

template<class... Inputs>

void fkie_message_filters::Sequencer< Inputs >::receive ( const Inputs &...  in )

overrideprotectedvirtual

Process incoming data.

Derived classes need to override this method to handle all data that is to be consumed by the sink.

Implements fkie_message_filters::Sink< Inputs... >.

Definition at line 47 of file sequencer_impl.h.

reset()

template<class... Inputs>

void fkie_message_filters::Sequencer< Inputs >::reset ( )

overridevirtualnoexcept

Reset filter state.

For stateful filters, this method resets the internal state as if the filter had just been created. Existing connections to sources and sinks are unaffected.

The default implementation does nothing.

Reimplemented from fkie_message_filters::FilterBase.

Definition at line 90 of file sequencer_impl.h.

set_max_delay()

template<class... Inputs>

void fkie_message_filters::Sequencer< Inputs >::set_max_delay ( const ros::Duration &  max_delay )

noexcept

Modify maximum delay.

New messages older than the most recently forwarded one will continue to be dropped, even if their delay is smaller than max_delay. In other words, a call to this method will never violate the temporal order constraint.

• max_delay the maximum delay of any message

Definition at line 40 of file sequencer_impl.h.

Member Data Documentation

cutoff_

template<class... Inputs>

ros::Time fkie_message_filters::Sequencer< Inputs >::cutoff_

private

Definition at line 80 of file sequencer.h.

max_delay_

template<class... Inputs>

ros::Duration fkie_message_filters::Sequencer< Inputs >::max_delay_

private

Definition at line 79 of file sequencer.h.

mutex_

template<class... Inputs>

std::mutex fkie_message_filters::Sequencer< Inputs >::mutex_

private

Definition at line 78 of file sequencer.h.

queue_

template<class... Inputs>

Queue fkie_message_filters::Sequencer< Inputs >::queue_

private

Definition at line 81 of file sequencer.h.

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

• sequencer.h
• sequencer_impl.h