make Functor DataHandles work with late binding in `start()`, see LHCb!3430

Phys/FunctorCore/include/Functors/Utilities.h

@@ -112,7 +112,39 @@ namespace Functors::detail {
     void bind_helper( Algorithm* alg, std::index_sequence<Is...> ) {
       static_assert( std::is_base_of_v<IDataHandleHolder, Algorithm>,
                      "You must include the full declaration of the owning algorithm type!" );
-      ( std::get<Is>( m_handles ).emplace( m_tes_locs[Is], alg ), ... );
+
+      if ( alg->msgLevel( MSG::DEBUG ) ) {
+        alg->info() << "Init of DataHandles of Functor (" + get_name( m_f ) + "):" << endmsg;
+      }
+      ( init_data_handle( std::get<Is>( m_handles ).emplace( m_tes_locs[Is], alg ), alg ), ... );
+    }
+
+    /**
+     * @brief  Initialize a TES DataHandle and check that the owning algorithm
+     * was configured correctly and already holds our input in ExtraInputs
+     *
+     * For more info on the logic please see the detailed explanation of how
+     * Functors obtain their data dependencies in FIXME(Link to where?)
+     *
+     * @param handle This handle will be initialized
+     * @param alg Algorithm/Tool which owns this functor
+     */
+    template <typename T, typename Algorithm>
+    void init_data_handle( DataObjectReadHandle<T>& handle, Algorithm* alg ) {
+      if ( alg->msgLevel( MSG::DEBUG ) ) { alg->info() << "  +  Init of DataHandle " << handle.objKey() << endmsg; }
+
+      if ( alg->extraInputDeps().count( handle.objKey() ) == 0 ) {
+        throw GaudiException{"Usage of DataHandle[\"" + handle.objKey() + "\"] in Functor (" + get_name( m_f ) +
+                                 ") requires that owning algorithm " + alg->name() +
+                                 " contains this TES location inside the ExtraInputs property. This is likely a "
+                                 "Configuration/PyConf bug!",
+                             get_name( m_f ), StatusCode::FAILURE};
+      }
+
+      // DataObjectReadHandle has a protected `init()` so we need to call it
+      // through it's base class. This is the same thing Gaudi::Algorithm does in
+      // sysInitialize()
+      static_cast<Gaudi::DataHandle*>( &handle )->init();
     }
 
     /** Make a tuple of references to the result of dereferencing each

Phys/FunctorCore/src/Components/Factory.cpp

@@ -114,6 +114,10 @@ struct FunctorFactory : public extends<Service, Functors::IFactory> {
 
     if ( msgLevel( MSG::VERBOSE ) ) { verbose() << "Full code to compile is:\n" << full_code << endmsg; }
 
+    // FIXME We should extend this to somehow include the hash of the
+    // precompiled header, otherwise library reusing is a bit of a dangerous
+    // game during development as you need to remember to delete the *.so
+    // objects
     auto const file_prefix =
         m_jit_lib_dir + "FunctorJitLib_" + Functors::Cache::hashToStr( Functors::Cache::makeHash( full_code ) );
     auto const lib_filename = file_prefix + ".so";
@@ -132,7 +136,7 @@ struct FunctorFactory : public extends<Service, Functors::IFactory> {
       info() << "Reusing functor library: " << lib_filename << endmsg;
     } else {
       auto const cpp_filename = file_prefix + ".cpp";
-      info() << "New functor library will be created based generated C++ file: " << cpp_filename << endmsg;
+      info() << "New functor library will be created with generated C++ file: " << cpp_filename << endmsg;
       {
         std::ofstream out( cpp_filename );
         out << full_code;

Phys/FunctorCore/src/FunctorDesc.cpp

@@ -14,9 +14,6 @@ namespace std {
   std::ostream& operator<<( std::ostream& o, ThOr::FunctorDesc const& f ) {
     using GaudiUtils::operator<<;
     return o << "\"(" << std::quoted( f.code, '\'' ) << ", "
-           << ", " << f.headers
-           << ", " << std::quoted( f.repr, '\'' )
-           << ")\""
-  ;
+             << ", " << f.headers << ", " << std::quoted( f.repr, '\'' ) << ")\"";
   }
 } // namespace std

Phys/FunctorCore/tests/options/functor_datahandle_test.py

+###############################################################################
+# (c) Copyright 2019 CERN for the benefit of the LHCb Collaboration           #
+#                                                                             #
+# This software is distributed under the terms of the GNU General Public      #
+# Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   #
+#                                                                             #
+# In applying this licence, CERN does not waive the privileges and immunities #
+# granted to it by virtue of its status as an Intergovernmental Organization  #
+# or submit itself to any jurisdiction.                                       #
+###############################################################################
+from Gaudi.Configuration import ApplicationMgr, VERBOSE
+from Configurables import Gaudi__Monitoring__MessageSvcSink as MessageSvcSink
+from Configurables import EvtStoreSvc
+from Functors import SIZE
+
+# algorithms are coming from PyConf because we need to use DataHandles etc.
+from PyConf.Algorithms import FunctorExampleAlg as FEA, Gaudi__Examples__VectorDataProducer as VDP
+from PyConf.dataflow import dataflow_config
+
+app = ApplicationMgr(OutputLevel=VERBOSE)
+# FEA has counters so we need a sink
+app.ExtSvc.append(MessageSvcSink())
+# why does the default EventDataSvc not work? good question!!!
+# FIXME make an issue for that
+whiteboard = EvtStoreSvc("EventDataSvc", EventSlots=1)
+app.ExtSvc.append(whiteboard)
+
+vdp = VDP(name="VDP")
+fea = FEA(name="FEA", Cut=SIZE(vdp.OutputLocation) < 5, OutputLevel=VERBOSE)
+
+# FIXME
+# make a test out of the below, which works in pyconf as long as we allow strings as DataHandles...
+# fea = FEA(name="FEA", Cut=SIZE(vdp.OutputLocation.location) < 5, OutputLevel=VERBOSE)
+# But is correctly caught on the C++ side and throws:
+# ERROR TES::Size  Usage of DataHandle["/Event/VDP/OutputLocation"] in Functor (TES::Size) requires that
+# owning algorithm FEA contains this TES location inside the ExtraInputs property. This is likely a Configuration/PyConf bug!
+
+c = dataflow_config()
+c.update(fea.configuration())
+algs, _ = c.apply()
+app.TopAlg = algs
+
+# - Event
+app.EvtMax = 1
+app.EvtSel = "NONE"
+app.HistogramPersistency = "NONE"
+
+# FIXME
+# 1. Add another test like the above with the HLTScheduler to show/test that algs get scheduled correctly