DPL: add ability to get the toplevel service registry

This will allows non DPL code to still exploit some of the
DPL services, like monitoring.

Author: ktf

Framework/Core/CMakeLists.txt

@@ -125,6 +125,7 @@ o2_add_library(Framework
                        src/RootArrowFilesystem.cxx
                        src/SendingPolicy.cxx
                        src/ServiceRegistry.cxx
+                       src/ServiceRegistryRef.cxx
                        src/ServiceSpec.cxx
                        src/SimpleResourceManager.cxx
                        src/SimpleRawDeviceService.cxx

Framework/Core/include/Framework/ServiceRegistryRef.h

@@ -112,6 +112,8 @@ class ServiceRegistryRef
     mRegistry.unlock(mSalt);
   }
 
+  static ServiceRegistryRef *globalDeviceRef(ServiceRegistryRef *ref = nullptr);
+
  private:
   ServiceRegistry& mRegistry;
   ServiceRegistry::Salt mSalt;

Framework/Core/src/ServiceRegistryRef.cxx

@@ -0,0 +1,25 @@
+// Copyright 2019-2026 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license 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.
+
+
+#include "Framework/ServiceRegistryRef.h"
+namespace o2::framework {
+
+ServiceRegistryRef *ServiceRegistryRef::globalDeviceRef(ServiceRegistryRef *ref) {
+  static ServiceRegistryRef *globalRef = nullptr;
+  if (!globalRef) {
+    globalRef = ref;
+  }
+  // We return a copy, so that it can be cache
+  return globalRef;
+}
+
+}

Framework/Core/src/runDataProcessing.cxx

@@ -1429,6 +1429,7 @@ int runStateMachine(DataProcessorSpecs const& workflow,
   // We initialise this in the driver, because different drivers might have
   // different versions of the service
   ServiceRegistry serviceRegistry;
+  ServiceRegistryRef::globalDeviceRef(new ServiceRegistryRef{serviceRegistry, ServiceRegistry::globalDeviceSalt()});
 
   if ((driverConfig.batch == false || getenv("DPL_DRIVER_REMOTE_GUI") != nullptr) && frameworkId.empty()) {
     debugGUI = initDebugGUI();