[core] Reduce allocation / deallocations necessary for Registration. (#…

…1744)

Provide `Util::CExpandingVector` (and unit tests) to be used as a replacement to std::vector / std::list occurences in the `Registration::SampleList` and sub-objects.
This vector does not destruct elements upon calling clear(), rather calls their clear() methods.

ecal/core/CMakeLists.txt

@@ -408,6 +408,7 @@ endif()
 set(ecal_util_src
     src/util/ecal_expmap.h
     src/util/ecal_thread.h
+    src/util/expanding_vector.h
     src/util/frequency_calculator.h
     src/util/getenvvar.h
 )

ecal/core/include/ecal/ecal_types.h

@@ -54,6 +54,13 @@ namespace eCAL
     {
         return std::tie(name, encoding, descriptor) < std::tie(rhs.name, rhs.encoding, rhs.descriptor);
     }
+
+    void clear()
+    {
+      name.clear();
+      encoding.clear();
+      descriptor.clear();
+    }
     //!< @endcond
   };
 

ecal/core/src/pubsub/ecal_pubgate.cpp

@@ -197,7 +197,7 @@ namespace eCAL
     const std::shared_lock<std::shared_timed_mutex> lock(m_topic_name_datawriter_sync);
     for (const auto& iter : m_topic_name_datawriter_map)
     {
-      reg_sample_list_.samples.emplace_back(iter.second->GetRegistration());
+      iter.second->GetRegistration(reg_sample_list_.push_back());
     }
   }
 }

ecal/core/src/pubsub/ecal_subgate.cpp

@@ -289,7 +289,7 @@ namespace eCAL
     const std::shared_lock<std::shared_timed_mutex> lock(m_topic_name_datareader_sync);
     for (const auto& iter : m_topic_name_datareader_map)
     {
-      reg_sample_list_.samples.emplace_back(iter.second->GetRegistration());
+      iter.second->GetRegistration(reg_sample_list_.push_back());
     }
   }
 }

ecal/core/src/readwrite/ecal_reader.cpp

@@ -594,7 +594,9 @@ namespace eCAL
   void CDataReader::Register()
   {
 #if ECAL_CORE_REGISTRATION
-    if (g_registration_provider() != nullptr) g_registration_provider()->RegisterSample(GetRegistrationSample());
+    Registration::Sample sample;
+    GetRegistrationSample(sample);
+    if (g_registration_provider() != nullptr) g_registration_provider()->RegisterSample(sample);
 
 #ifndef NDEBUG
     // log it
@@ -606,7 +608,9 @@ namespace eCAL
   void CDataReader::Unregister()
   {
 #if ECAL_CORE_REGISTRATION
-    if (g_registration_provider() != nullptr) g_registration_provider()->UnregisterSample(GetUnregistrationSample());
+    Registration::Sample sample;
+    GetUnregistrationSample(sample);
+    if (g_registration_provider() != nullptr) g_registration_provider()->UnregisterSample(sample);
 
 #ifndef NDEBUG
     // log it
@@ -615,10 +619,10 @@ namespace eCAL
 #endif // ECAL_CORE_REGISTRATION
   }
 
-  Registration::Sample CDataReader::GetRegistration()
+  void CDataReader::GetRegistration(Registration::Sample& sample)
   {
     // return registration
-    return GetRegistrationSample();
+    return GetRegistrationSample(sample);
   }
 
   bool CDataReader::IsPublished() const
@@ -631,10 +635,8 @@ namespace eCAL
     return m_connection_count;
   }
 
-  Registration::Sample CDataReader::GetRegistrationSample()
+  void CDataReader::GetRegistrationSample(Registration::Sample& ecal_reg_sample)
   {
-    // create registration sample
-    Registration::Sample ecal_reg_sample;
     ecal_reg_sample.cmd_type = bct_reg_subscriber;
 
     auto& ecal_reg_sample_identifier = ecal_reg_sample.identifier;
@@ -706,14 +708,10 @@ namespace eCAL
     // we do not know the number of connections ..
     ecal_reg_sample_topic.connections_loc = 0;
     ecal_reg_sample_topic.connections_ext = 0;
-
-    return ecal_reg_sample;
   }
 
-  Registration::Sample CDataReader::GetUnregistrationSample()
+  void CDataReader::GetUnregistrationSample(Registration::Sample& ecal_unreg_sample)
   {
-    // create unregistration sample
-    Registration::Sample ecal_unreg_sample;
     ecal_unreg_sample.cmd_type = bct_unreg_subscriber;
 
     auto& ecal_reg_sample_identifier = ecal_unreg_sample.identifier;
@@ -726,8 +724,6 @@ namespace eCAL
     ecal_reg_sample_topic.pname  = m_pname;
     ecal_reg_sample_topic.tname  = m_topic_name;
     ecal_reg_sample_topic.uname  = Process::GetUnitName();
-
-    return ecal_unreg_sample;
   }
 
   void CDataReader::StartTransportLayer()

ecal/core/src/readwrite/ecal_reader.h

@@ -86,7 +86,7 @@ namespace eCAL
 
     void ApplyLayerParameter(const SPublicationInfo& publication_info_, eTLayerType type_, const Registration::ConnectionPar& parameter_);
 
-    Registration::Sample GetRegistration();
+    void GetRegistration(Registration::Sample& sample);
     bool IsCreated() const { return(m_created); }
 
     bool IsPublished() const;
@@ -115,8 +115,8 @@ namespace eCAL
     void Register();
     void Unregister();
 
-    Registration::Sample GetRegistrationSample();
-    Registration::Sample GetUnregistrationSample();
+    void GetRegistrationSample(Registration::Sample& sample);
+    void GetUnregistrationSample(Registration::Sample& sample);
 
     void StartTransportLayer();
     void StopTransportLayer();

ecal/core/src/readwrite/ecal_writer.cpp

@@ -628,7 +628,9 @@ namespace eCAL
   void CDataWriter::Register()
   {
 #if ECAL_CORE_REGISTRATION
-    if (g_registration_provider() != nullptr) g_registration_provider()->RegisterSample(GetRegistrationSample());
+    Registration::Sample registration_sample;
+    GetRegistrationSample(registration_sample);
+    if (g_registration_provider() != nullptr) g_registration_provider()->RegisterSample(registration_sample);
 
 #ifndef NDEBUG
     // log it
@@ -640,7 +642,9 @@ namespace eCAL
   void CDataWriter::Unregister()
   {
 #if ECAL_CORE_REGISTRATION
-    if (g_registration_provider() != nullptr) g_registration_provider()->UnregisterSample(GetUnregistrationSample());
+    Registration::Sample unregistration_sample;
+    GetUnregistrationSample(unregistration_sample);
+    if (g_registration_provider() != nullptr) g_registration_provider()->UnregisterSample(unregistration_sample);
 
 #ifndef NDEBUG
     // log it
@@ -649,15 +653,13 @@ namespace eCAL
 #endif // ECAL_CORE_REGISTRATION
   }
 
-  Registration::Sample CDataWriter::GetRegistration()
+  void CDataWriter::GetRegistration(Registration::Sample& sample)
   {
-    return GetRegistrationSample();
+    GetRegistrationSample(sample);
   }
 
-  Registration::Sample CDataWriter::GetRegistrationSample()
+  void CDataWriter::GetRegistrationSample(Registration::Sample& ecal_reg_sample)
   {
-    // create registration sample
-    Registration::Sample ecal_reg_sample;
     ecal_reg_sample.cmd_type = bct_reg_publisher;
 
     auto& ecal_reg_sample_identifier = ecal_reg_sample.identifier;
@@ -748,14 +750,10 @@ namespace eCAL
     }
     ecal_reg_sample_topic.connections_loc = static_cast<int32_t>(loc_connections);
     ecal_reg_sample_topic.connections_ext = static_cast<int32_t>(ext_connections);
-
-    return ecal_reg_sample;
   }
 
-  Registration::Sample CDataWriter::GetUnregistrationSample()
+  void CDataWriter::GetUnregistrationSample(Registration::Sample& ecal_unreg_sample)
   {
-    // create unregistration sample
-    Registration::Sample ecal_unreg_sample;
     ecal_unreg_sample.cmd_type = bct_unreg_publisher;
 
     auto& ecal_reg_sample_identifier = ecal_unreg_sample.identifier;
@@ -768,8 +766,6 @@ namespace eCAL
     ecal_reg_sample_topic.pname  = m_pname;
     ecal_reg_sample_topic.tname  = m_topic_name;
     ecal_reg_sample_topic.uname  = Process::GetUnitName();
-
-    return ecal_unreg_sample;
   }
 
   void CDataWriter::FireConnectEvent(const std::string& tid_, const SDataTypeInformation& tinfo_)

ecal/core/src/readwrite/ecal_writer.h

@@ -92,7 +92,7 @@ namespace eCAL
     void ApplySubscription(const SSubscriptionInfo& subscription_info_, const SDataTypeInformation& data_type_info_, const SLayerStates& sub_layer_states_, const std::string& reader_par_);
     void RemoveSubscription(const SSubscriptionInfo& subscription_info_);
 
-    Registration::Sample GetRegistration();
+    void GetRegistration(Registration::Sample& sample);
     void RefreshSendCounter();
 
     bool IsCreated() const { return(m_created); }
@@ -119,8 +119,8 @@ namespace eCAL
     void Register();
     void Unregister();
 
-    Registration::Sample GetRegistrationSample();
-    Registration::Sample GetUnregistrationSample();
+    void GetRegistrationSample(Registration::Sample& sample);
+    void GetUnregistrationSample(Registration::Sample& sample);
 
     bool StartUdpLayer();
     bool StartShmLayer();

ecal/core/src/registration/ecal_registration_provider.cpp

@@ -30,6 +30,7 @@
 #include <atomic>
 #include <chrono>
 #include <functional>
+#include <iterator>
 #include <memory>
 #include <mutex>
 #include <string>
@@ -136,46 +137,47 @@ namespace eCAL
   void CRegistrationProvider::AddSingleSample(const Registration::Sample& sample_)
   {
     const std::lock_guard<std::mutex> lock(m_applied_sample_list_mtx);
-    m_applied_sample_list.samples.push_back(sample_);
+    m_applied_sample_list.push_back(sample_);
   }
 
   void CRegistrationProvider::RegisterSendThread()
   {
     // collect all registrations and send them out cyclic
     {
       // create sample list
-      Registration::SampleList sample_list;
+      m_send_thread_sample_list.clear();
 
       // and add process registration sample
-      sample_list.samples.push_back(Registration::GetProcessRegisterSample());
+      m_send_thread_sample_list.push_back(Registration::GetProcessRegisterSample());
 
 #if ECAL_CORE_SUBSCRIBER
       // add subscriber registrations
-      if (g_subgate() != nullptr) g_subgate()->GetRegistrations(sample_list);
+      if (g_subgate() != nullptr) g_subgate()->GetRegistrations(m_send_thread_sample_list);
 #endif
 
 #if ECAL_CORE_PUBLISHER
       // add publisher registrations
-      if (g_pubgate() != nullptr) g_pubgate()->GetRegistrations(sample_list);
+      if (g_pubgate() != nullptr) g_pubgate()->GetRegistrations(m_send_thread_sample_list);
 #endif
 
 #if ECAL_CORE_SERVICE
       // add server registrations
-      if (g_servicegate() != nullptr) g_servicegate()->GetRegistrations(sample_list);
+      if (g_servicegate() != nullptr) g_servicegate()->GetRegistrations(m_send_thread_sample_list);
 
       // add client registrations
-      if (g_clientgate() != nullptr) g_clientgate()->GetRegistrations(sample_list);
+      if (g_clientgate() != nullptr) g_clientgate()->GetRegistrations(m_send_thread_sample_list);
 #endif
 
       // append applied samples list to sample list
-      if (!m_applied_sample_list.samples.empty())
+      if (!m_applied_sample_list.empty())
       {
         const std::lock_guard<std::mutex> lock(m_applied_sample_list_mtx);
-        sample_list.samples.splice(sample_list.samples.end(), m_applied_sample_list.samples);
+        std::copy(m_applied_sample_list.begin(), m_applied_sample_list.end(), std::back_inserter(m_send_thread_sample_list));
+        m_applied_sample_list.clear();
       }
 
       // send collected registration sample list
-      m_reg_sender->SendSampleList(sample_list);
+      m_reg_sender->SendSampleList(m_send_thread_sample_list);
     }
   }
 }

ecal/core/src/registration/ecal_registration_provider.h

@@ -65,6 +65,8 @@ namespace eCAL
     std::mutex                           m_applied_sample_list_mtx;
     Registration::SampleList             m_applied_sample_list;
 
+    Registration::SampleList             m_send_thread_sample_list;
+
     Registration::SAttributes                  m_attributes;
   };
 }

ecal/core/src/registration/shm/ecal_registration_receiver_shm.cpp

@@ -70,15 +70,17 @@ namespace eCAL
 
   void CRegistrationReceiverSHM::Receive()
   {
+    // At the moment this function is called synchronously by a dedicated thread.
+    // If this changes, we need to protect the sample list member variable
     MemfileBroadcastMessageListT message_list;
     if (m_memfile_broadcast_reader->Read(message_list, 0))
     {
-      eCAL::Registration::SampleList sample_list;
+      m_sample_list.clear();
       for (const auto& message : message_list)
       {
-        if (DeserializeFromBuffer(static_cast<const char*>(message.data), message.size, sample_list))
+        if (DeserializeFromBuffer(static_cast<const char*>(message.data), message.size, m_sample_list))
         {
-          for (const auto& sample : sample_list.samples)
+          for (const auto& sample : m_sample_list)
           {
             m_apply_sample_callback(sample);
           }

ecal/core/src/registration/shm/ecal_registration_receiver_shm.h

@@ -59,6 +59,8 @@ namespace eCAL
     std::unique_ptr<CMemoryFileBroadcastReader> m_memfile_broadcast_reader;
     std::unique_ptr<CCallbackThread>            m_memfile_broadcast_reader_thread;
 
+    eCAL::Registration::SampleList              m_sample_list;
+
     RegistrationApplySampleCallbackT m_apply_sample_callback;
   };
 }

ecal/core/src/registration/udp/ecal_registration_sender_udp.cpp

@@ -58,7 +58,7 @@ namespace eCAL
   bool CRegistrationSenderUDP::SendSampleList(const Registration::SampleList& sample_list)
   {
     bool return_value{ true };
-    for (const auto& sample : sample_list.samples)
+    for (const auto& sample : sample_list)
     {
       return_value &= SendSample(sample);
     }