received_message_age.hpp

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// Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef LIBSTATISTICS_COLLECTOR__TOPIC_STATISTICS_COLLECTOR__RECEIVED_MESSAGE_AGE_HPP_
#define LIBSTATISTICS_COLLECTOR__TOPIC_STATISTICS_COLLECTOR__RECEIVED_MESSAGE_AGE_HPP_
 
#include <chrono>
#include <string>
#include <sstream>
#include <type_traits>
#include <utility>
 
#include "constants.hpp"
 
#include "libstatistics_collector/topic_statistics_collector/topic_statistics_collector.hpp"
 
#include "rcl/time.h"
#include "rcutils/logging_macros.h"
 
namespace libstatistics_collector
{
namespace topic_statistics_collector
{
 
template<typename M, typename = void>
struct HasHeader : public std::false_type {};
 
template<typename M>
struct HasHeader<M, decltype((void) M::header)>: std::true_type {};
 
template<typename M, typename Enable = void>
struct TimeStamp
{
  static std::pair<bool, int64_t> value(const M &)
  {
    return std::make_pair(false, 0);
  }
};
 
template<typename M>
struct TimeStamp<M, typename std::enable_if<HasHeader<M>::value>::type>
{
  static std::pair<bool, int64_t> value(const M & m)
  {
    const auto stamp = m.header.stamp;
    const auto nanos = RCL_S_TO_NS(static_cast<int64_t>(stamp.sec)) + stamp.nanosec;
    return std::make_pair(true, nanos);
  }
};
 
template<typename T>
class ReceivedMessageAgeCollector : public TopicStatisticsCollector<T>
{
public:
  ReceivedMessageAgeCollector() = default;
 
  virtual ~ReceivedMessageAgeCollector() = default;
 
  void OnMessageReceived(
    const T & received_message,
    const rcl_time_point_value_t now_nanoseconds) override
  {
    const auto timestamp_from_header = TimeStamp<T>::value(received_message);
 
    if (timestamp_from_header.first) {
      // only compare if non-zero
      if (timestamp_from_header.second && now_nanoseconds) {
        const std::chrono::nanoseconds age_nanos{now_nanoseconds - timestamp_from_header.second};
        const auto age_millis = std::chrono::duration_cast<std::chrono::milliseconds>(age_nanos);
 
        collector::Collector::AcceptData(static_cast<double>(age_millis.count()));
      }  // else no valid time to compute age
    }
  }
 
  std::string GetMetricName() const override
  {
    return topic_statistics_constants::kMsgAgeStatName;
  }
 
  std::string GetMetricUnit() const override
  {
    return topic_statistics_constants::kMillisecondUnitName;
  }
 
protected:
  bool SetupStart() override
  {
    return true;
  }
 
  bool SetupStop() override
  {
    return true;
  }
};
 
}  // namespace topic_statistics_collector
}  // namespace libstatistics_collector
 
#endif  // LIBSTATISTICS_COLLECTOR__TOPIC_STATISTICS_COLLECTOR__RECEIVED_MESSAGE_AGE_HPP_