fkie_message_filters::combiner_policies::ExactTime< IOs > Class Template Reference

Exact time policy. More...

#include <fkie_message_filters/combiner_policies/exact_time.h>

Inheritance diagram for fkie_message_filters::combiner_policies::ExactTime< IOs >:

Collaboration diagram for fkie_message_filters::combiner_policies::ExactTime< IOs >:

Public Types
using	EmitterCB = std::function< void(const OutgoingTuple &)>
	Callback for assembled outputs.
using	IncomingTuples = std::tuple< helpers::io_tuple_t< IOs >... >
	Tuple type of incoming data tuples.
using	OutgoingTuple = helpers::io_tuple_t< helpers::io_concat_t< IOs... > >
	Combined tuple type for data output.

Public Member Functions
	ExactTime ()
	Constructor. More...
ExactTime &	set_max_age (const ros::Duration &max_age) noexcept
	Set maximum age of any data in the queue. More...
ExactTime &	set_max_queue_size (std::size_t queue_size, const boost::optional< ros::Duration > &max_age=boost::none) noexcept
	Set maximum queue size. More...

Protected Types
using	MaybeOutgoingTuples = std::tuple< boost::optional< helpers::io_tuple_t< IOs > >... >
	Tuple of outgoing tuple candidates. More...

Protected Member Functions
template<std::size_t N>
void	add (std::unique_lock< std::mutex > &, const std::tuple_element_t< N, IncomingTuples > &)
	Input function. More...
void	emit (const OutgoingTuple &out)
	Emit data. More...
void	reset () noexcept override
	Reset internal state. More...
void	set_emitter_callback (const EmitterCB &) noexcept
	Set output function. More...

Detailed Description

template<typename... IOs>
class fkie_message_filters::combiner_policies::ExactTime< IOs >

Exact time policy.

This is a policy for the Combiner class. It will associate data from the connected sources when their ROS header timestamp match exactly. If an input source is not unary, only the first argument of each input will be examined to determine the timestamp. It must have an accessible ROS header, which is determined using the ros::message_traits template.

The policy will discard unmatched data which exceeds configurable age limit or overflows the maximum queue size. The resulting timestamps will be strictly increasing if at least one of the inputs receives messages in correct temporal order. Whenever matched data is emitted, all queued inputs with older timestamps will be discarded.

The filter will not output any data at all if the time lag between two inputs is larger than the maximum permissible age, or if the time lag requires more messages to be buffered than the maximum queue size permits. By default, the filter will buffer arbitrary many messages for at most one second.

Member Typedef Documentation

MaybeOutgoingTuples

using fkie_message_filters::combiner_policies::PolicyBase< IOs >::MaybeOutgoingTuples = std::tuple<boost::optional<helpers::io_tuple_t<IOs> >...>

protectedinherited

Tuple of outgoing tuple candidates.

This is basically a tuple of optionals, so elements can remain empty until a suitable data element has been found by the policy.

Constructor & Destructor Documentation

ExactTime()

template<typename... IOs>

fkie_message_filters::combiner_policies::ExactTime< IOs >::ExactTime

(

)

Constructor.

Exceptions

Does not throw any exceptions.

Member Function Documentation

add()

template<typename... IOs>

template<std::size_t N>

void fkie_message_filters::combiner_policies::ExactTime< IOs >::add ( std::unique_lock< std::mutex > &  , const std::tuple_element_t< N, IncomingTuples > &    )

protected

Input function.

This function will be called by the Combiner class for incoming data.

emit()

void fkie_message_filters::combiner_policies::PolicyBase< IOs >::emit ( const OutgoingTuple &  out )

protectedinherited

Emit data.

This returns combined data back to the Combiner class.

reset()

template<typename... IOs>

void fkie_message_filters::combiner_policies::ExactTime< IOs >::reset ( )

overrideprotectedvirtualnoexcept

Reset internal state.

This function is called by the Combiner if the filter is reset.

Implements fkie_message_filters::combiner_policies::PolicyBase< IOs... >.

set_emitter_callback()

void fkie_message_filters::combiner_policies::PolicyBase< IOs >::set_emitter_callback ( const EmitterCB &  )

protectednoexceptinherited

Set output function.

This function is called by the policy whenever it has output ready to be passed on.

set_max_age()

template<typename... IOs>

ExactTime& fkie_message_filters::combiner_policies::ExactTime< IOs >::set_max_age ( const ros::Duration &  max_age )

noexcept

Set maximum age of any data in the queue.

This is equivalent to

set_max_queue_size(0, max_age);

• max_age maximum age

Exceptions

Does not throw any exceptions.

set_max_queue_size()

template<typename... IOs>

ExactTime& fkie_message_filters::combiner_policies::ExactTime< IOs >::set_max_queue_size ( std::size_t  queue_size, const boost::optional< ros::Duration > &  max_age = boost::none  )

noexcept

Set maximum queue size.

• queue_size maximum queue size per slot (zero means unlimited)
• max_age the maximum age of any data in the queue

Exceptions

Does not throw any exceptions.

---

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

• include/fkie_message_filters/combiner_policies/exact_time.h