This could probably be a race condition, for ex: When we've create a …

…subscriber in the API, and the subscriber has the data already available in the callback (Cause of existing publishers) the db entry for the particular topic would not be availalble, which in turn returns an SqliteException. This is cause write_->create_topic() call is where we add the db entry for a particular topic. And, this leads to crashing before any recording.

Locally I solved it by adding the db entry first, and if
create_subscription fails, remove the topic entry from the db and also
erase the subscription.

Signed-off-by: Sriram Raghunathan <rsriram7@visteon.com>

rosbag2_transport/src/rosbag2_transport/recorder.cpp

@@ -106,6 +106,11 @@ void Recorder::subscribe_topics(
 
 void Recorder::subscribe_topic(const rosbag2::TopicMetadata & topic)
 {
+  if(writer_) {
+    writer_->create_topic(topic);
+    subscribed_topics_.insert(topic.name);
+  }
+
   auto subscription = create_subscription(topic.name, topic.type);
 
   if (subscription) {
@@ -117,6 +122,11 @@ void Recorder::subscribe_topic(const rosbag2::TopicMetadata & topic)
     writer_->remove_topic(topic);
     subscribed_topics_.erase(topic.name);
   }
+  else {
+    writer_->remove_topic(topic);
+    subscribed_topics_.erase(topic.name);
+  }
+
 }
 
 std::shared_ptr<GenericSubscription>