buffer.cpp

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/*
 * Copyright (c) 2008, Willow Garage, Inc.
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 *
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 *       this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include "tf2_ros/buffer.h"

#include <ros/assert.h>
#include <sstream>

namespace tf2_ros
{

static const double CAN_TRANSFORM_POLLING_SCALE = 0.01;

Buffer::Buffer(ros::Duration cache_time, bool debug) :
  BufferCore(cache_time)
{
  if(debug && !ros::service::exists("~tf2_frames", false))
  {
    ros::NodeHandle n("~");
    frames_server_ = n.advertiseService("tf2_frames", &Buffer::getFrames, this);
  }
}

geometry_msgs::TransformStamped 
Buffer::lookupTransform(const std::string& target_frame, const std::string& source_frame,
                        const ros::Time& time, const ros::Duration timeout) const
{
  canTransform(target_frame, source_frame, time, timeout);
  return lookupTransform(target_frame, source_frame, time);
}


geometry_msgs::TransformStamped 
Buffer::lookupTransform(const std::string& target_frame, const ros::Time& target_time,
                        const std::string& source_frame, const ros::Time& source_time,
                        const std::string& fixed_frame, const ros::Duration timeout) const
{
  canTransform(target_frame, target_time, source_frame, source_time, fixed_frame, timeout);
  return lookupTransform(target_frame, target_time, source_frame, source_time, fixed_frame);
}

ros::Time now_fallback_to_wall()
{
  try
  {
    return ros::Time::now();
  }
  catch (ros::TimeNotInitializedException ex)
  {
    ros::WallTime wt = ros::WallTime::now(); 
    return ros::Time(wt.sec, wt.nsec); 
  }
}

void sleep_fallback_to_wall(const ros::Duration& d)
{
  try
  {
      d.sleep();
  }
  catch (ros::TimeNotInitializedException ex)
  {
    ros::WallDuration wd = ros::WallDuration(d.sec, d.nsec); 
    wd.sleep();
  }
}

void conditionally_append_timeout_info(std::string * errstr, const ros::Time& start_time,
                                       const ros::Duration& timeout)
{
  if (errstr)
  {
    std::stringstream ss;
    ss << ". canTransform returned after "<< (now_fallback_to_wall() - start_time).toSec() \
       <<" timeout was " << timeout.toSec() << ".";
    (*errstr) += ss.str();
  }
}

bool
Buffer::canTransform(const std::string& target_frame, const std::string& source_frame, 
                     const ros::Time& time, const ros::Duration timeout, std::string* errstr) const
{
  // Clear the errstr before populating it if it's valid.
  if (errstr)
    {
      errstr->clear();
    }

  if (!checkAndErrorDedicatedThreadPresent(errstr))
    return false;

  // poll for transform if timeout is set
  ros::Time start_time = now_fallback_to_wall();
  const ros::Duration sleep_duration = timeout * CAN_TRANSFORM_POLLING_SCALE;
  while (now_fallback_to_wall() < start_time + timeout && 
         !canTransform(target_frame, source_frame, time) &&
         (now_fallback_to_wall()+ros::Duration(3.0) >= start_time) &&  //don't wait when we detect a bag loop
         (ros::ok() || !ros::isInitialized())) // Make sure we haven't been stopped (won't work for pytf)
    {
      sleep_fallback_to_wall(sleep_duration);
    }
  bool retval = canTransform(target_frame, source_frame, time, errstr);
  conditionally_append_timeout_info(errstr, start_time, timeout);
  return retval;
}

    
bool
Buffer::canTransform(const std::string& target_frame, const ros::Time& target_time,
                     const std::string& source_frame, const ros::Time& source_time,
                     const std::string& fixed_frame, const ros::Duration timeout, std::string* errstr) const
{
  // Clear the errstr before populating it if it's valid.
  if (errstr)
    {
      errstr->clear();
    }

  if (!checkAndErrorDedicatedThreadPresent(errstr))
    return false;

  // poll for transform if timeout is set
  ros::Time start_time = now_fallback_to_wall();
  const ros::Duration sleep_duration = timeout * CAN_TRANSFORM_POLLING_SCALE;
  while (now_fallback_to_wall() < start_time + timeout && 
         !canTransform(target_frame, target_time, source_frame, source_time, fixed_frame) &&
         (now_fallback_to_wall()+ros::Duration(3.0) >= start_time) &&  //don't wait when we detect a bag loop
         (ros::ok() || !ros::isInitialized())) // Make sure we haven't been stopped (won't work for pytf)
         {  
           sleep_fallback_to_wall(sleep_duration);
         }
  bool retval = canTransform(target_frame, target_time, source_frame, source_time, fixed_frame, errstr);
  conditionally_append_timeout_info(errstr, start_time, timeout);
  return retval; 
}


bool Buffer::getFrames(tf2_msgs::FrameGraph::Request& req, tf2_msgs::FrameGraph::Response& res) 
{
  res.frame_yaml = allFramesAsYAML();
  return true;
}



bool Buffer::checkAndErrorDedicatedThreadPresent(std::string* error_str) const
{
  if (isUsingDedicatedThread())
    return true;
  


  if (error_str)
    *error_str = tf2_ros::threading_error;

  ROS_ERROR("%s", tf2_ros::threading_error.c_str());
  return false;
}



}