From a0a19ef15c905e526825518d984077ee16f8ab66 Mon Sep 17 00:00:00 2001
From: Nathan Brei <nbrei@jlab.org>
Date: Mon, 30 Sep 2024 13:05:13 -0400
Subject: [PATCH] Podio event source: Use new, exception-free Emit() callback

---
 src/services/io/podio/JEventSourcePODIO.cc | 19 ++++++++++---------
 src/services/io/podio/JEventSourcePODIO.h  |  4 ++--
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/services/io/podio/JEventSourcePODIO.cc b/src/services/io/podio/JEventSourcePODIO.cc
index 1d60140ff2..3950069918 100644
--- a/src/services/io/podio/JEventSourcePODIO.cc
+++ b/src/services/io/podio/JEventSourcePODIO.cc
@@ -69,6 +69,7 @@ struct InsertingVisitor {
 //------------------------------------------------------------------------------
 JEventSourcePODIO::JEventSourcePODIO(std::string resource_name, JApplication* app) : JEventSource(resource_name, app) {
     SetTypeName(NAME_OF_THIS); // Provide JANA with class name
+    SetCallbackStyle(CallbackStyle::ExpertMode); // Use new, exception-free Emit() callback
 
     // Tell JANA that we want it to call the FinishEvent() method.
     // EnableFinishEvent();
@@ -185,7 +186,7 @@ void JEventSourcePODIO::Close() {
 ///
 /// \param event
 //------------------------------------------------------------------------------
-void JEventSourcePODIO::GetEvent(std::shared_ptr<JEvent> event) {
+JEventSourcePODIO::Result JEventSourcePODIO::Emit(JEvent& event) {
 
     /// Calls to GetEvent are synchronized with each other, which means they can
     /// read and write state on the JEventSource without causing race conditions.
@@ -194,10 +195,9 @@ void JEventSourcePODIO::GetEvent(std::shared_ptr<JEvent> event) {
     if( Nevents_read >= Nevents_in_file ) {
         if( m_run_forever ){
             Nevents_read = 0;
-        }else{
-            // m_reader.close();
-            // TODO:: ROOTFrameReader does not appear to have a close() method.
-            throw RETURN_STATUS::kNO_MORE_EVENTS;
+        }
+        else{
+            return Result::FailureFinished;
         }
     }
 
@@ -208,19 +208,20 @@ void JEventSourcePODIO::GetEvent(std::shared_ptr<JEvent> event) {
     if (event_headers.size() != 1) {
         throw JException("Bad event headers: Entry %d contains %d items, but 1 expected.", Nevents_read, event_headers.size());
     }
-    event->SetEventNumber(event_headers[0].getEventNumber());
-    event->SetRunNumber(event_headers[0].getRunNumber());
+    event.SetEventNumber(event_headers[0].getEventNumber());
+    event.SetRunNumber(event_headers[0].getRunNumber());
 
     // Insert contents odf frame into JFactories
     VisitPodioCollection<InsertingVisitor> visit;
     for (const std::string& coll_name : frame->getAvailableCollections()) {
         const podio::CollectionBase* collection = frame->get(coll_name);
-        InsertingVisitor visitor(*event, coll_name);
+        InsertingVisitor visitor(event, coll_name);
         visit(visitor, *collection);
     }
 
-    event->Insert(frame.release()); // Transfer ownership from unique_ptr to JFactoryT<podio::Frame>
+    event.Insert(frame.release()); // Transfer ownership from unique_ptr to JFactoryT<podio::Frame>
     Nevents_read += 1;
+    return Result::Success;
 }
 
 //------------------------------------------------------------------------------
diff --git a/src/services/io/podio/JEventSourcePODIO.h b/src/services/io/podio/JEventSourcePODIO.h
index 21dc45c999..8e053c49a4 100644
--- a/src/services/io/podio/JEventSourcePODIO.h
+++ b/src/services/io/podio/JEventSourcePODIO.h
@@ -9,7 +9,7 @@
 #include <JANA/JEventSource.h>
 #include <JANA/JEventSourceGeneratorT.h>
 #include <podio/ROOTFrameReader.h>
-#include <stddef.h>
+#include <cstddef>
 #include <memory>
 #include <set>
 #include <string>
@@ -25,7 +25,7 @@ class JEventSourcePODIO : public JEventSource {
 
     void Close() override;
 
-    void GetEvent(std::shared_ptr<JEvent>) override;
+    Result Emit(JEvent& event) override;
 
     static std::string GetDescription();