Program Listing for File time_cache.h

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// Copyright 2008, Willow Garage, Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//    * Redistributions of source code must retain the above copyright
//      notice, this list of conditions and the following disclaimer.
//
//    * Redistributions in binary form must reproduce the above copyright
//      notice, this list of conditions and the following disclaimer in the
//      documentation and/or other materials provided with the distribution.
//
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//      contributors may be used to endorse or promote products derived from
//      this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#ifndef TF2__TIME_CACHE_H_
#define TF2__TIME_CACHE_H_

#include <chrono>
#include <memory>
#include <list>
#include <sstream>
#include <string>
#include <utility>

#include "tf2/visibility_control.h"
#include "tf2/transform_storage.h"

namespace tf2
{
typedef std::pair<tf2::TimePoint, tf2::CompactFrameID> P_TimeAndFrameID;

class TimeCacheInterface
{
public:
  TF2_PUBLIC
  virtual ~TimeCacheInterface() = default;

  TF2_PUBLIC
  virtual bool getData(
    tf2::TimePoint time, tf2::TransformStorage & data_out,
    std::string * error_str = 0) = 0;

  TF2_PUBLIC
  virtual bool insertData(const tf2::TransformStorage & new_data) = 0;

  TF2_PUBLIC
  virtual void clearList() = 0;

  TF2_PUBLIC
  virtual CompactFrameID getParent(tf2::TimePoint time, std::string * error_str) = 0;

  TF2_PUBLIC
  virtual P_TimeAndFrameID getLatestTimeAndParent() = 0;


  TF2_PUBLIC
  virtual unsigned int getListLength() = 0;

  TF2_PUBLIC
  virtual tf2::TimePoint getLatestTimestamp() = 0;

  TF2_PUBLIC
  virtual tf2::TimePoint getOldestTimestamp() = 0;
};

using TimeCacheInterfacePtr = std::shared_ptr<TimeCacheInterface>;

constexpr tf2::Duration TIMECACHE_DEFAULT_MAX_STORAGE_TIME = std::chrono::seconds(10);

class TimeCache : public TimeCacheInterface
{
public:
  TF2_PUBLIC
  static const int MIN_INTERPOLATION_DISTANCE = 5;

  TF2_PUBLIC
  static const unsigned int MAX_LENGTH_LINKED_LIST = 1000000;

  TF2_PUBLIC
  explicit TimeCache(tf2::Duration max_storage_time = TIMECACHE_DEFAULT_MAX_STORAGE_TIME);


  TF2_PUBLIC
  virtual bool getData(
    tf2::TimePoint time, tf2::TransformStorage & data_out,
    std::string * error_str = 0);
  TF2_PUBLIC
  virtual bool insertData(const tf2::TransformStorage & new_data);
  TF2_PUBLIC
  virtual void clearList();
  TF2_PUBLIC
  virtual tf2::CompactFrameID getParent(tf2::TimePoint time, std::string * error_str);
  TF2_PUBLIC
  virtual P_TimeAndFrameID getLatestTimeAndParent();

  TF2_PUBLIC
  virtual unsigned int getListLength();
  TF2_PUBLIC
  virtual TimePoint getLatestTimestamp();
  TF2_PUBLIC
  virtual TimePoint getOldestTimestamp();

protected:
  // (Internal) Return a reference to the internal list of tf2 frames, which
  // are sorted in timestamp order.
  // Any items with the same timestamp will be in reverse order of insertion.
  TF2_PUBLIC
  const std::list<TransformStorage> & getAllItems() const;

private:
  typedef std::list<TransformStorage> L_TransformStorage;
  L_TransformStorage storage_;

  tf2::Duration max_storage_time_;


  // A helper function for getData
  // Assumes storage is already locked for it
  inline uint8_t findClosest(
    tf2::TransformStorage * & one, TransformStorage * & two,
    tf2::TimePoint target_time, std::string * error_str);

  inline void interpolate(
    const tf2::TransformStorage & one, const tf2::TransformStorage & two,
    tf2::TimePoint time, tf2::TransformStorage & output);

  void pruneList();
};

class StaticCache : public TimeCacheInterface
{
public:
  TF2_PUBLIC
  virtual bool getData(TimePoint time, TransformStorage & data_out, std::string * error_str = 0);
  // returns false if data unavailable (should be thrown as lookup exception
  TF2_PUBLIC
  virtual bool insertData(const TransformStorage & new_data);
  TF2_PUBLIC
  virtual void clearList();
  TF2_PUBLIC
  virtual CompactFrameID getParent(TimePoint time, std::string * error_str);
  TF2_PUBLIC
  virtual P_TimeAndFrameID getLatestTimeAndParent();

  TF2_PUBLIC
  virtual unsigned int getListLength();
  TF2_PUBLIC
  virtual TimePoint getLatestTimestamp();
  TF2_PUBLIC
  virtual TimePoint getOldestTimestamp();

private:
  TransformStorage storage_;
};
}  // namespace tf2
#endif  // TF2__TIME_CACHE_H_