/usr/include/message_filters/time_sequencer.h is in libmessage-filters-dev 1.13.5+ds1-3.
This file is owned by root:root, with mode 0o644.
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#ifndef MESSAGE_FILTERS_TIME_SEQUENCER_H
#define MESSAGE_FILTERS_TIME_SEQUENCER_H
#include <ros/ros.h>
#include "connection.h"
#include "simple_filter.h"
namespace message_filters
{
/**
* \class TimeSequencer
*
* \brief Sequences messages based on the timestamp of their header.
*
* The TimeSequencer object is templated on the type of message being sequenced.
*
* \section behavior BEHAVIOR
* At construction, the TimeSequencer takes a ros::Duration
* "delay" which specifies how long to queue up messages to
* provide a time sequencing over them. As messages arrive they are
* sorted according to their time stamps. A callback for a message is
* never invoked until the messages' time stamp is out of date by at
* least delay. However, for all messages which are out of date
* by at least delay, their callback are invoked and guaranteed
* to be in temporal order. If a message arrives from a time \b prior
* to a message which has already had its callback invoked, it is
* thrown away.
*
* \section connections CONNECTIONS
*
* TimeSequencer's input and output connections are both of the same signature as roscpp subscription callbacks, ie.
\verbatim
void callback(const boost::shared_ptr<M const>&);
\endverbatim
*
*/
template<class M>
class TimeSequencer : public SimpleFilter<M>
{
public:
typedef boost::shared_ptr<M const> MConstPtr;
typedef ros::MessageEvent<M const> EventType;
/**
* \brief Constructor
* \param f A filter to connect this sequencer's input to
* \param delay The minimum time to hold a message before passing it through.
* \param update_rate The rate at which to check for messages which have passed "delay"
* \param queue_size The number of messages to store
* \param nh (optional) The NodeHandle to use to create the ros::Timer that runs at update_rate
*/
template<class F>
TimeSequencer(F& f, ros::Duration delay, ros::Duration update_rate, uint32_t queue_size, ros::NodeHandle nh = ros::NodeHandle())
: delay_(delay)
, update_rate_(update_rate)
, queue_size_(queue_size)
, nh_(nh)
{
init();
connectInput(f);
}
/**
* \brief Constructor
*
* This version of the constructor does not take a filter immediately. You can connect to a filter later with the connectInput() function
*
* \param delay The minimum time to hold a message before passing it through.
* \param update_rate The rate at which to check for messages which have passed "delay"
* \param queue_size The number of messages to store
* \param nh (optional) The NodeHandle to use to create the ros::Timer that runs at update_rate
*/
TimeSequencer(ros::Duration delay, ros::Duration update_rate, uint32_t queue_size, ros::NodeHandle nh = ros::NodeHandle())
: delay_(delay)
, update_rate_(update_rate)
, queue_size_(queue_size)
, nh_(nh)
{
init();
}
/**
* \brief Connect this filter's input to another filter's output.
*/
template<class F>
void connectInput(F& f)
{
incoming_connection_.disconnect();
incoming_connection_ = f.registerCallback(typename SimpleFilter<M>::EventCallback(boost::bind(&TimeSequencer::cb, this, _1)));
}
~TimeSequencer()
{
update_timer_.stop();
incoming_connection_.disconnect();
}
void add(const EventType& evt)
{
namespace mt = ros::message_traits;
boost::mutex::scoped_lock lock(messages_mutex_);
if (mt::TimeStamp<M>::value(*evt.getMessage()) < last_time_)
{
return;
}
messages_.insert(evt);
if (queue_size_ != 0 && messages_.size() > queue_size_)
{
messages_.erase(*messages_.begin());
}
}
/**
* \brief Manually add a message to the cache.
*/
void add(const MConstPtr& msg)
{
EventType evt(msg);
add(evt);
}
private:
class MessageSort
{
public:
bool operator()(const EventType& lhs, const EventType& rhs) const
{
namespace mt = ros::message_traits;
return mt::TimeStamp<M>::value(*lhs.getMessage()) < mt::TimeStamp<M>::value(*rhs.getMessage());
}
};
typedef std::multiset<EventType, MessageSort> S_Message;
typedef std::vector<EventType> V_Message;
void cb(const EventType& evt)
{
add(evt);
}
void dispatch()
{
namespace mt = ros::message_traits;
V_Message to_call;
{
boost::mutex::scoped_lock lock(messages_mutex_);
while (!messages_.empty())
{
const EventType& e = *messages_.begin();
ros::Time stamp = mt::TimeStamp<M>::value(*e.getMessage());
if (stamp + delay_ <= ros::Time::now())
{
last_time_ = stamp;
to_call.push_back(e);
messages_.erase(messages_.begin());
}
else
{
break;
}
}
}
{
typename V_Message::iterator it = to_call.begin();
typename V_Message::iterator end = to_call.end();
for (; it != end; ++it)
{
this->signalMessage(*it);
}
}
}
void update(const ros::TimerEvent&)
{
dispatch();
}
void init()
{
update_timer_ = nh_.createTimer(update_rate_, &TimeSequencer::update, this);
}
ros::Duration delay_;
ros::Duration update_rate_;
uint32_t queue_size_;
ros::NodeHandle nh_;
ros::Timer update_timer_;
Connection incoming_connection_;
S_Message messages_;
boost::mutex messages_mutex_;
ros::Time last_time_;
};
}
#endif
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