TEventProxyDict.cxx

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// Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
//
// File holding the implementation of the xAOD::TEvent functions that implement
// the IProxyDict interface. Just to make TEvent.cxx a little smaller.
//
 
// System include(s):
#include <stdexcept>
#include <set>
 
// ROOT include(s):
#include <TClass.h>
#include <TString.h>
#include <TBranch.h>
 
// Offline include(s):
#ifndef XAOD_STANDALONE
#   include "SGTools/DataProxy.h"
#   include "SGTools/TransientAddress.h"
#   include "AthenaKernel/DataBucketBase.h"
#   include "GaudiKernel/Converter.h"
#   include "GaudiKernel/GenericAddress.h"
#endif // NOT XAOD_STANDALONE
 
#include "AthContainers/tools/threading.h"
#include "CxxUtils/checker_macros.h"
#include "xAODRootAccess/TEvent.h"
#include "xAODRootAccess/tools/Message.h"
#include "xAODRootAccess/tools/THolder.h"
#include "xAODRootAccess/tools/TObjectManager.h"
 
 
 
namespace {
   typedef AthContainers_detail::mutex mutex_t;
   typedef AthContainers_detail::lock_guard< mutex_t > guard_t;
}
 
 
#ifndef XAOD_STANDALONE
namespace xAODPrivate {
 
   class THolderBucket : public DataBucketBase {
 
   public:
      THolderBucket( const std::string& key,
                     const std::type_info& ti,
                     xAOD::TEvent& event )
         : m_key( key ), m_ti( ti ), m_event( event ) {}
 
      void* object() override {
 
         // Look among the output objects first:
         const void* result = m_event.getOutputObject( m_key, m_ti );
         // Check if it succeeded:
         if( ! result ) {
            // Try the input then:
            result = m_event.getInputObject( m_key, m_ti );
         } else {
            // Even if there is an output object with this key, it may
            // be an input object that was copied to the output. So let's
            // try to silently retrieve an input object as well. This makes
            // sure that the input/output object is updated for the current
            // event.
            m_event.getInputObject( m_key, m_ti, kTRUE );
         }
 
         // Return the pointer:
         void* nc_result ATLAS_THREAD_SAFE = const_cast< void* >( result ); //DataBucketBase interface
         return nc_result;
      }
 
      const std::type_info& tinfo() const override {
 
         return m_ti;
      }
 
      void* cast( CLID, SG::IRegisterTransient*,
                  bool ) override {
 
         throw std::runtime_error( "THolderBucket::cast not implemented" );
         return 0;
      }
 
      void* cast( const std::type_info& tinfo,
                  SG::IRegisterTransient*,
                  bool isConst ) override {
 
         // Do the cast:
         static const bool QUIET = true;
         const void* result = 0;
         if( isConst ) {
            // Just look among the inputs:
            result = m_event.getInputObject( m_key, tinfo, QUIET );
         } else {
            // Look among the output objects first:
            result = m_event.getOutputObject( m_key, tinfo, QUIET );
            // Check if it succeeded:
            if( ! result ) {
               // Try the input then:
               result = m_event.getInputObject( m_key, tinfo, QUIET );
            } else {
               // Even if there is an output object with this key, it may
               // be an input object that was copied to the output. So let's
               // try to silently retrieve an input object as well. This makes
               // sure that the input/output object is updated for the current
               // event.
               m_event.getInputObject( m_key, tinfo, QUIET );
            }
         }
 
         // Return the pointer:
         void* nc_result ATLAS_THREAD_SAFE = const_cast< void* >( result ); //DataBucketBase interface
         return nc_result;
      }
 
      void* cast( CLID,
                  const std::type_info& tinfo,
                  SG::IRegisterTransient* irt,
                  bool isConst) override
      {
         return THolderBucket::cast (tinfo, irt, isConst);
      }
 
      void relinquish() override {}
      void lock() override {}
 
   private:
      const std::string m_key;
      const std::type_info& m_ti;
      xAOD::TEvent& m_event;
 
   }; // class THolderBucket
 
   class TLoader
     : public Converter
   {
   public:
     TLoader (xAOD::TEvent& event,
              const std::string& name,
              const std::type_info& ti)
       :  Converter (0, CLID_NULL),
          m_event (event),
          m_name (name),
          m_ti (ti),
          m_proxy (nullptr)
     {
     }
 
 
     void setProxy (SG::DataProxy& proxy)
     {
       m_proxy = &proxy;
     }
 
 
     virtual StatusCode createObj(IOpaqueAddress*, DataObject*&) override;
     virtual long repSvcType() const override { return 0; }
 
 
   private:
     xAOD::TEvent& m_event;
     std::string m_name;
     const std::type_info& m_ti;
     SG::DataProxy* m_proxy;
   };
 
 
   StatusCode TLoader::createObj(IOpaqueAddress* /*addr*/, DataObject*& obj)
   {
     static const bool SILENT = true;
     static const bool METADATA = false;
     
     // Try to find the object amongst the output objects first:
     if( m_event.getOutputObject( m_name, m_ti, METADATA ) ) {
       obj = new xAODPrivate::THolderBucket( m_name, m_ti, m_event);
     }
     // If it's not on the output, try the input:
     else if( m_event.getInputObject( m_name, m_ti, SILENT, METADATA ) ) {
       obj = new xAODPrivate::THolderBucket( m_name, m_ti, m_event);
       m_proxy->setConst();
     }
 
     return StatusCode::SUCCESS;
   }
 
} // xAODPrivate namespace
#endif // not XAOD_STANDALONE
 
namespace xAOD {
 
   SG::DataProxy* TEvent::proxy( const void* const pTransient ) const {
 
      // Look up the name of this object
      std::string name = getName( pTransient );
      if( name.empty() ) {
         // Apparently the object is not known...
         return nullptr;
      }
 
      // Get the metadata object for it:
      const xAOD::EventFormatElement* efe = 0;
      static const bool QUIET = true;
      if( m_outputEventFormat ) {
         efe = m_outputEventFormat->get( name, QUIET );
      }
      if( ! efe ) {
         efe = m_inputEventFormat.get( name, QUIET );
      }
      if( ! efe ) {
         // No metadata found...
         return nullptr;
      }
 
      // Return the proxy:
      const BranchInfo* bi = getBranchInfo( efe->hash() );
      return bi->m_proxy.get();
   }
 
   SG::DataProxy* TEvent::proxy( const CLID&,
                                 const std::string& key ) const {
 
      const SG::sgkey_t sgkey = getHash( key );
      if( ! sgkey ) {
         return 0;
      }
      return proxy_exact( sgkey );
   }
 
   SG::DataProxy* TEvent::proxy_exact( SG::sgkey_t sgkey ) const {
 
      // Get the object describing this branch/object:
      const BranchInfo* bi = getBranchInfo( sgkey );
      if( ! bi ) {
         static SG::SGKeySet missingSGKeys ATLAS_THREAD_SAFE;
         static mutex_t mutex;
         guard_t lock(mutex);
         if( missingSGKeys.emplace( sgkey ).second &&
             m_printEventProxyWarnings) {
            ::Warning( "xAOD::TEvent::proxy_exact",
                       "Can't find BranchInfo for %d.",
                       sgkey );
         }
         return 0;
      }
 
      // Access its data proxy:
      SG::DataProxy* proxy = bi->m_proxy.get();
 
      // Return the proxy:
      return proxy;
   }
 
   const TEvent::BranchInfo* TEvent::getBranchInfo( SG::sgkey_t sgkey ) const {
 
     {
       // We can only hold the lock (even though it's a shared lock) for
       // this limited scope because the call to getInputObject below
       // leads to a recursion and dead-lock if not released immediately.
       upgrading_lock_t lock(m_branchesMutex);
 
       // If the object already exists, return it:
       auto it = m_branches.find( sgkey );
       if( it != m_branches.end() ) {
         return &( it->second );
       }
     }
 
      // If not, construct it now:
      BranchInfo bi;
      const xAOD::EventFormatElement* efe = getEventFormatElement( sgkey );
      if( ! efe ) {
         // Apparently this key is not known:
         return nullptr;
      }
 
      // Helper variable(s).
      static const bool SILENT = true;
      static const bool METADATA = false;
 
      // The name of the requested object.
      const std::string& name = getName( sgkey );
      // This is a bit perverse... In order to let the "base class" figure
      // out the exact type of this object, we ask for it with a TEvent
      // pointer. I use that type because I need something that has a
      // dictionary, and which should always be available when this code
      // runs. In the end it doesn't matter that the object can't be
      // retrieved as that type (of course...), it only matters that it gets
      // "set up" following these calls.
      TEvent* nc_this = const_cast< TEvent* >( this );
      static const std::type_info& dummy = typeid( TEvent );
      nc_this->getInputObject( name, dummy, SILENT, METADATA );
      auto itr = m_outputObjects.find( name );
      if( itr == m_outputObjects.end() ) {
         itr = m_inputObjects.find( name );
         if( itr == m_inputObjects.end() ) {
            // We didn't find this object in the store...
            return nullptr;
         }
      }
      const TObjectManager* mgr =
         dynamic_cast< const TObjectManager* >( itr->second );
      if( ! mgr ) {
         ::Error( "xAOD::TEvent::getBranchInfo",
                  XAOD_MESSAGE( "Internal logic error found" ) );
         return nullptr;
      }
      bi.m_class = mgr->holder()->getClass();
      // There's no need to check whether this is a "proper" dictionary
      // at this point, since if TEvent is holding on to it, the type
      // must have a proper compiled dictionary.
 
#ifndef XAOD_STANDALONE
      // Create a proper proxy for the input branch:
      SG::TransientAddress* taddr =
         new SG::TransientAddress( CLID_NULL, efe->branchName(),
                                   new GenericAddress() );
      taddr->setSGKey( sgkey );
      xAODPrivate::TLoader* loader =
        new xAODPrivate::TLoader (*nc_this,
                                  getName( sgkey ),
                                  *bi.m_class->GetTypeInfo());
      bi.m_proxy.reset( new SG::DataProxy( taddr, loader ) );
      loader->setProxy (*bi.m_proxy.get());
#endif // not XAOD_STANDALONE
 
      // Add the branch info to our list:
      upgrading_lock_t lock(m_branchesMutex);
      lock.upgrade();
      auto ret = m_branches.insert( std::make_pair( sgkey, std::move( bi ) ) );
 
      // Return a pointer to the branch info:
      return &( ret.first->second );
   }
 
   const xAOD::EventFormatElement*
   TEvent::getEventFormatElement( SG::sgkey_t sgkey ) const {
 
      const xAOD::EventFormatElement* efe = 0;
      static const bool QUIET = true;
      if( m_outputEventFormat ) {
         efe = m_outputEventFormat->get( sgkey, QUIET );
      }
      if( ! efe ) {
         efe = m_inputEventFormat.get( sgkey, QUIET );
      }
      if ( ! efe ) {
         static SG::SGKeySet missingSGKeys ATLAS_THREAD_SAFE;
         static mutex_t mutex;
         guard_t lock(mutex);
         if( missingSGKeys.emplace( sgkey ).second ) {
            if (m_printEventProxyWarnings) {
               ::Warning( "xAOD::TEvent::getEventFormatElement",
                          "Can't find EventFormatElement for hashed "
                          "SG key %d", sgkey );
            }
            return 0;
         }
      }
      return efe;
   }
 
   StatusCode TEvent::addToStore( CLID clid, SG::DataProxy* proxy ) {
 
      upgrading_lock_t lock(m_branchesMutex);
 
      // Warn the user that the function got called:
      static std::atomic_flag warningPrinted ATLAS_THREAD_SAFE = ATOMIC_FLAG_INIT;
      if ( ! warningPrinted.test_and_set() && m_printEventProxyWarnings) {
          ::Warning( "xAOD::TEvent::addToStore",
                    "Function should only be called through an invalid "
                    "ElementLink" );
      }
 
      // Hold on to the proxy with some non-existent, hopefully unique key:
      const ::TString uniqueKey = ::TString::Format( "NonExistentKey_%lu",
                                                     m_branches.size() );
      BranchInfo bi;
      bi.m_proxy.reset( proxy );
      lock.upgrade();
      m_branches.insert( std::make_pair( stringToKey( uniqueKey.Data(),
                                                      clid ),
                                         std::move( bi ) ) );
 
      // Return gracefully:
      return StatusCode::SUCCESS;
   }
 
   std::vector< const SG::DataProxy* > TEvent::proxies() const {
 
      upgrading_lock_t lock(m_branchesMutex);
 
      std::vector< const SG::DataProxy* > ret;
      for( const auto& p : m_branches ) {
         const SG::DataProxy* proxy = p.second.m_proxy.get();
         if( proxy ) {
            ret.push_back( proxy );
         }
      }
      return ret;
   }
 
   SG::sgkey_t TEvent::stringToKey( const std::string& str, CLID ) {
 
      return getHash( str );
   }
 
   const std::string* TEvent::keyToString( SG::sgkey_t key ) const {
 
      return &( getName( key ) );
   }
 
   const std::string* TEvent::keyToString( SG::sgkey_t key, CLID& ) const {
 
      return &( getName( key ) );
   }
 
   void TEvent::registerKey( SG::sgkey_t, const std::string&, CLID ) {
 
      return;
   }
 
   SG::DataProxy* TEvent::recordObject( SG::DataObjectSharedPtr<DataObject>,
                                        const std::string&, bool, bool ) {
 
      throw std::runtime_error( "xAOD::TEvent::recordObject is not "
                                "implemented" );
   }
 
   const std::string& TEvent::name() const {
 
      static const std::string NAME = "xAOD::TEvent";
      return NAME;
   }
 
} // namespace xAOD