locked_robot_state.h

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/* Author: Ioan Sucan, Acorn Pooley */

#ifndef MOVEIT_ROBOT_INTERACTION_LOCKED_ROBOT_STATE_
#define MOVEIT_ROBOT_INTERACTION_LOCKED_ROBOT_STATE_

#include <moveit/robot_state/robot_state.h>
#include <boost/function.hpp>
#include <boost/thread.hpp>

namespace robot_interaction
{

//
// Only allow one thread to modify the RobotState at a time.
//
// Allow any thread access to the RobotState when it is not being modified.  If
// a (const) reference to the robot state is held when the RobotState needs to
// be modified, a copy is made and the copy is modified.  Any externally held
// references will be out of date but still valid.
//
// The RobotState can only be modified by passing a callback function which
// does the modification.
class LockedRobotState
{
public:
  LockedRobotState(const robot_state::RobotState& state);
  LockedRobotState(const robot_model::RobotModelPtr& model);

  virtual ~LockedRobotState();

  //
  // This state may go stale, meaning the maintained state has been updated,
  // but it will never be modified while the caller is holding a reference to
  // it.
  //
  // The transforms in the returned state will always be up to date.
  robot_state::RobotStateConstPtr getState() const;

  void setState(const robot_state::RobotState& state);

  // This is a function that can modify the maintained state.
  typedef boost::function<void (robot_state::RobotState*)> ModifyStateFunction;
  
  // Modify the state.
  //
  // This modifies the state by calling \e modify on it.
  // The \e modify function is passed a reference to the state which it can
  // modify.  No threads will be given access to the state while the \e modify
  // function is running.
  void modifyState(const ModifyStateFunction& modify);

protected:
  // This is called when the internally maintained state has changed.
  // This is called with state_lock_ unlocked.
  // Default definition does nothing.  Override to get notification of state
  // change.
  // TODO: is this needed?
  virtual void robotStateChanged();

protected:
  // this locks all accesses to the state_ member.
  // The lock can also be used by subclasses to lock additional fields.
  mutable boost::mutex state_lock_;

private:
  // The state maintained by this class.
  // When a modify function is being called this is NULL.
  // PROTECTED BY state_lock_
  robot_state::RobotStatePtr state_;
};

typedef boost::shared_ptr<LockedRobotState> LockedRobotStatePtr;
typedef boost::shared_ptr<const LockedRobotState> LockedRobotStateConstPtr;

}

#endif