PodioDataSvc.h

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// SPDX-License-Identifier: LGPL-3.0-or-later
// Copyright (C) 2022 Whitney Armstrong, Wouter Deconinck
 
#ifndef JUGBASE_PODIODATASVC_H
#define JUGBASE_PODIODATASVC_H
 
#include <GaudiKernel/DataSvc.h>
#include <GaudiKernel/IConversionSvc.h>
// PODIO
#include <podio/CollectionBase.h>
#include <podio/CollectionIDTable.h>
#include <podio/EventStore.h>
#include <podio/ROOTReader.h>
 
#include <utility>
// Forward declarations
 
/** @class PodioEvtSvc EvtDataSvc.h
 *
 *   An EvtDataSvc for PODIO classes
 *
 *  @author B. Hegner
 *
 *  \ingroup base
 */
class PodioDataSvc : public DataSvc {
public:
  typedef std::vector<std::pair<std::string, podio::CollectionBase*>> CollRegistry;
 
  /** Initialize the service.
   *  - attaches data loader
   *  - registers input filenames  
   */
  virtual StatusCode initialize() override;
  virtual StatusCode reinitialize() override;
  virtual StatusCode finalize() override;
  virtual StatusCode clearStore() override;
 
  /// Standard Constructor
  PodioDataSvc(const std::string& name, ISvcLocator* svc);
 
  /// Standard Destructor
  virtual ~PodioDataSvc();
 
  // Use DataSvc functionality except where we override
  using DataSvc::registerObject;
  /// Overriding standard behaviour of evt service
  /// Register object with the data store.
  virtual StatusCode registerObject(std::string_view parentPath,
                                    std::string_view fullPath,
                                    DataObject* pObject) override final;
 
  StatusCode readCollection(const std::string& collectionName, int collectionID);
 
  virtual const CollRegistry& getCollections() const { return m_collections; }
  virtual const CollRegistry& getReadCollections() const { return m_readCollections; }
  podio::EventStore& getProvider() { return m_provider; }
  virtual podio::CollectionIDTable* getCollectionIDs() { return m_collectionIDs; }
 
  /// Set the collection IDs (if reading a file)
  void setCollectionIDs(podio::CollectionIDTable* collectionIds);
  /// Resets caches of reader and event store, increases event counter
  void endOfRead();
 
 
  TTree* eventDataTree() {return m_eventDataTree;}
 
 
private:
 
  // eventDataTree
  TTree* m_eventDataTree;
  /// PODIO reader for ROOT files
  podio::ROOTReader m_reader;
  /// PODIO EventStore, used to initialise collections
  podio::EventStore m_provider;
  /// Counter of the event number
  int m_eventNum{0};
  /// Number of events in the file / to process
  int m_eventMax{-1};
 
 
  SmartIF<IConversionSvc> m_cnvSvc;
 
  // special members for podio handling
  std::vector<std::pair<std::string, podio::CollectionBase*>> m_collections;
  std::vector<std::pair<std::string, podio::CollectionBase*>> m_readCollections;
  podio::CollectionIDTable* m_collectionIDs;
 
protected:
  /// ROOT file name the input is read from. Set by option filename
  std::vector<std::string> m_filenames;
  std::string m_filename;
  /// Jump to nth events at the beginning. Set by option FirstEventEntry
  /// This option is helpful when we want to debug an event in the middle of a file
  unsigned m_1stEvtEntry{0};
};
#endif