fix observer

Author: facontidavide

examples/t10_observer.cpp

@@ -63,20 +63,20 @@ int main()
     std::cout << uid << " -> " << name << std::endl;
   }
 
-  // Tick the tree multiple times, until action_B is finally ticked.
-  // Since we use const reference, we can check this statistic periodically.
-  const auto& action_B_stats = observer.getStatistics("last_action");
 
-  tree.tickOnce();
+  tree.tickWhileRunning();
 
+  // You can access a specific statistic, using is full path or the UID
+  const auto& last_action_stats = observer.getStatistics("last_action");
+  assert(last_action_stats.transitions_count > 0);
 
   std::cout << "----------------" << std::endl;
   // print all the statistics
   for(const auto& [uid, name]: ordered_UID_to_path) {
     const auto& stats = observer.getStatistics(uid);
 
     std::cout << "[" << name
-              << "] \tT/S/F:  " << stats.tick_count
+              << "] \tT/S/F:  " << stats.transitions_count
               << "/" << stats.success_count
               << "/" << stats.failure_count
               << std::endl;

include/behaviortree_cpp/loggers/bt_observer.h

@@ -22,11 +22,20 @@ class TreeObserver : public StatusChangeLogger
 
   struct NodeStatistics
   {
+    // Last __valid__ result, either SUCCESS or FAILURE
     NodeStatus last_result = NodeStatus::IDLE;
+    // Last status. Can be any status, including IDLE or SKIPPED
     NodeStatus current_status = NodeStatus::IDLE;
+
+    // count status transitions, excluding transition to IDLE
+    unsigned transitions_count = 0;
+    // count number of transitions to SUCCESS
     unsigned success_count = 0;
+    // count number of transitions to FAILURE
     unsigned failure_count = 0;
-    unsigned tick_count = 0;
+    // count number of transitions to SKIPPED
+    unsigned skip_count = 0;
+
     Duration last_timestamp = {};
   };
 

src/loggers/bt_observer.cpp

@@ -51,21 +51,29 @@ void TreeObserver::callback(Duration timestamp, const TreeNode& node,
                             NodeStatus /*prev_status*/, NodeStatus status)
 {
   auto& statistics = _statistics[node.UID()];
-
-  statistics.tick_count++;
   statistics.current_status = status;
   statistics.last_timestamp = timestamp;
 
+  if(status == NodeStatus::IDLE) {
+    return;
+  }
+
+  statistics.transitions_count++;
+
   if(status == NodeStatus::SUCCESS)
   {
-    statistics.last_result = NodeStatus::SUCCESS;
+    statistics.last_result = status;
     statistics.success_count++;
   }
   else if(status == NodeStatus::FAILURE)
   {
-    statistics.last_result = NodeStatus::FAILURE;
+    statistics.last_result = status;
     statistics.failure_count++;
   }
+  else if(status == NodeStatus::SKIPPED)
+  {
+    statistics.skip_count++;
+  }
 }
 
 const TreeObserver::NodeStatistics& TreeObserver::getStatistics(const std::string &path) const