.. _program_listing_file_include_libstatistics_collector_topic_statistics_collector_received_message_age.hpp:

Program Listing for File received_message_age.hpp
=================================================

|exhale_lsh| :ref:`Return to documentation for file <file_include_libstatistics_collector_topic_statistics_collector_received_message_age.hpp>` (``include/libstatistics_collector/topic_statistics_collector/received_message_age.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   // 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 "builtin_interfaces/msg/time.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, typename std::enable_if<std::is_same<builtin_interfaces::msg::Time,
     decltype(M().header.stamp)>::value>::type>: public 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<double, std::milli>(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_