Added mutex for subscriber's message updates.

StefanFabian · Mar 21, 2022 · 8af695e · 8af695e
1 parent a9d4931
commit 8af695e
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Showing 2 changed files with 10 additions and 6 deletions.
diff --git a/include/qml_ros_plugin/subscriber.h b/include/qml_ros_plugin/subscriber.h
@@ -126,7 +126,7 @@ protected slots:
   ros::Subscriber subscriber_;
   ros_babel_fish::BabelFish babel_fish_;
   ros_babel_fish::BabelFishMessage::ConstPtr last_message_;
-  ros_babel_fish::BabelFishMessage::ConstPtr current_message_;
+  std::mutex message_mutex_;
   QTimer throttle_timer_;
   bool running_;
   bool is_subscribed_;

diff --git a/src/subscriber.cpp b/src/subscriber.cpp
@@ -123,18 +123,22 @@ void Subscriber::shutdown()
 
 void Subscriber::messageCallback( const ros_babel_fish::BabelFishMessage::ConstPtr &msg )
 {
+  std::lock_guard<std::mutex> lock( message_mutex_ );
   last_message_ = msg;
 }
 
 void Subscriber::updateMessage()
 {
-  if (current_message_ == last_message_) return;
-  current_message_ = last_message_;
-  TranslatedMessage::Ptr translated = babel_fish_.translateMessage( current_message_ );
+  std::unique_lock<std::mutex> lock( message_mutex_ );
+  if ( !last_message_ ) return;
+  ros_babel_fish::BabelFishMessage::ConstPtr msg = std::move( last_message_ );
+  last_message_ = nullptr;
+  lock.unlock(); // Don't need the mutex anymore
+  TranslatedMessage::Ptr translated = babel_fish_.translateMessage( msg );
   message_ = msgToMap( translated, translated->translated_message->as<CompoundMessage>());
-  if (current_message_->dataType() != message_type_.toStdString())
+  if ( msg->dataType() != message_type_.toStdString())
   {
-    message_type_ = QString::fromStdString(current_message_->dataType());
+    message_type_ = QString::fromStdString( msg->dataType());
     emit messageTypeChanged();
   }
   emit messageChanged();