Cosmics: load the ITS tracks of legs with an ITS part

With --track-sources containing ITS-TPC (or another source with ITS) but
not ITS, the matcher's winner refit and the cluster collector read the ITS
track of such a leg (getITSTrack, its cluster references), which was
neither requested nor read: segfault in refitWinner, then in the
collector; without an ITS road there was also no ITS cluster reader
(invalid workflow). The ITS tracks and clusters are now requested and read
for these legs, without making standalone ITS tracks legs (seed sources
unchanged). TPC-only legs (physics-v1 in async) are not affected.

PbPb 567939, 4 TFs, --track-sources TPC,ITS-TPC: all TFs processed with
and without the ITS road (crash before), no ITS-only legs (seeds 23318
vs 26345 with ITS as legs); TPC-only legs: unchanged, no ITS track reader.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: matthias-kleiner

Detectors/GlobalTrackingWorkflow/include/GlobalTrackingWorkflow/CosmicsMatchingSpec.h

@@ -24,6 +24,9 @@ namespace globaltracking
 {
 
 /// create a processor spec
+/// ITS tracks needed by legs with an ITS part (their refit and ITS clusters) if ITS tracks are no legs themselves
+o2::dataformats::GlobalTrackID::mask_t getLegITSSources(o2::dataformats::GlobalTrackID::mask_t src);
+
 /// srcPVContributors plus the parent matches needed to resolve their single-detector parts (RecoContainer::getSingleDetectorRefs)
 o2::dataformats::GlobalTrackID::mask_t addPVContributorParents(o2::dataformats::GlobalTrackID::mask_t srcPVContributors);
 

Detectors/GlobalTrackingWorkflow/src/CosmicsClusterCollectorSpec.cxx

@@ -65,6 +65,7 @@
 #include "Framework/DataProcessorSpec.h"
 #include "Framework/DeviceSpec.h"
 #include "GlobalTrackingWorkflow/CosmicsClusterCollectorSpec.h"
+#include "GlobalTrackingWorkflow/CosmicsMatchingSpec.h"
 #include "DataFormatsGlobalTracking/RecoContainer.h"
 #include "DataFormatsGlobalTracking/TrackCosmicsExtended.h"
 #include "ReconstructionDataFormats/TrackCosmics.h"
@@ -1610,6 +1611,7 @@ DataProcessorSpec getCosmicsClusterCollectorSpec(GTrackID::mask_t src, bool useM
   auto dataRequest = std::make_shared<DataRequest>();
   dataRequest->setITSPerLayer(itsStag);
   dataRequest->requestTracks(src, false);
+  dataRequest->requestTracks(getLegITSSources(src), false); // the ITS clusters of legs with an ITS part are read through their ITS track
   dataRequest->requestClusters(src, false);
   if (roadDets[DetID::ITS]) {
     dataRequest->requestITSClusters(false);

Detectors/GlobalTrackingWorkflow/src/CosmicsMatchingSpec.cxx

@@ -187,6 +187,11 @@ void CosmicsMatchingSpec::endOfStream(EndOfStreamContext& ec)
        mTimer.CpuTime(), mTimer.RealTime(), mTimer.Counter() - 1);
 }
 
+GTrackID::mask_t getLegITSSources(GTrackID::mask_t src)
+{
+  return GTrackID::includesDet(o2::detectors::DetID::ITS, src) ? GTrackID::getSourceMask(GTrackID::ITS) & ~src : GTrackID::mask_t{};
+}
+
 GTrackID::mask_t addPVContributorParents(GTrackID::mask_t srcPVContributors)
 {
   auto src = srcPVContributors;
@@ -213,6 +218,7 @@ DataProcessorSpec getCosmicsMatchingSpec(GTrackID::mask_t src, bool usePV, bool
   dataRequest->setITSPerLayer(itsStag);
 
   dataRequest->requestTracks(src, useMC);
+  dataRequest->requestTracks(getLegITSSources(src), false); // the refit of legs with an ITS part reads their ITS track
   dataRequest->requestClusters(src, false); // no MC labels for clusters needed for refit only
   if (useTOFClusters) {
     dataRequest->requestTOFClusters(false); // TOF flight pairs of the candidate pairs (MatchCosmicsParams::tofFlightSelection)

Detectors/GlobalTrackingWorkflow/src/cosmics-match-workflow.cxx

@@ -118,7 +118,9 @@ WorkflowSpec defineDataProcessing(ConfigContext const& configcontext)
     src = src | GID::getSourcesMask("CTP");
   }
 
-  GID::mask_t srcCl = src;
+  // legs with an ITS part need the ITS tracks and clusters for their refit, also if standalone ITS tracks are no legs (not added to src)
+  const GID::mask_t srcITS = o2::globaltracking::getLegITSSources(src);
+  GID::mask_t srcCl = src | srcITS;
   const bool useTOFClusters = o2::globaltracking::MatchCosmicsParams::Instance().tofFlightSelection;
   if (useTOFClusters) {
     srcCl |= GID::getSourceMask(GID::TOF);
@@ -151,7 +153,7 @@ WorkflowSpec defineDataProcessing(ConfigContext const& configcontext)
     specs.emplace_back(o2::globaltracking::getCosmicsClusterCollectorSpec(src, useMC, doStag, roadDets));
   }
 
-  o2::globaltracking::InputHelper::addInputSpecs(configcontext, specs, srcCl, src | srcPVLoaded, src | srcPVLoaded, useMC, dummy); // clusters MC is not needed
+  o2::globaltracking::InputHelper::addInputSpecs(configcontext, specs, srcCl, src | srcPVLoaded | srcITS, src | srcPVLoaded | srcITS, useMC, dummy); // clusters MC is not needed
   if (usePV) {
     o2::globaltracking::InputHelper::addInputSpecsPVertex(configcontext, specs, useMC); // P-vertex is always needed
   }