[root6] Eliminate crash when creating the MuDst

[klendathu2k]

When creating the MuDst, ROOT6 has a problem with creating the TClonesArray
of StStrangeAssoc objects. Running under GDB shows that TClass::GetClass enters
an infinite recursion... almost as if the system is confused, and believes the class is it's
own base class.

Disabling the call to initializeForWriting() on loading the share library resolves the issue.
Though I don't know what side effects this may cause.

[veprbl]

The original code was introduced over two decades ago: a20c9a8#diff-9b5c84904f9c5ac927afddab6e4379e15fe6fa757afa4130bde3883f5ec15a3a

It is a bit suspicious that the modification to the global StObject streamer configuration is made conditional on loading of StStrangeMuDstMaker (which, IIRC, is itself loaded unconditionally in most of our BFC configurations).

I think, it would be nice to aim at removing this option for ROOT 5 as well. There may be some file size implications for MuDsts, but those can be addressed on a class-by-class basis.

[veprbl]

This advances the ROOT6 tests in CI to the fCurrentRow woes. Very exciting.

[plexoos]

This is a great finding indeed. The function calls which seem to disturb ROOT6 can be moved to StStrangeMuDstMaker. That is how it is done in MuDst and PicoDst for the persistent objects:

star-sw/StRoot/StMuDSTMaker/COMMON/StMuDstMaker.cxx

Lines 478 to 509 in 25274b6

	void StMuDstMaker::streamerOff() {
	StMuEvent::Class()->IgnoreTObjectStreamer();
	StMuL3EventSummary::Class()->IgnoreTObjectStreamer();
	#ifndef __NO_STRANGE_MUDST__
	StStrangeMuDst::Class()->IgnoreTObjectStreamer();
	StV0MuDst::Class()->IgnoreTObjectStreamer();
	StXiMuDst::Class()->IgnoreTObjectStreamer();
	StKinkMuDst::Class()->IgnoreTObjectStreamer();
	StV0Mc::Class()->IgnoreTObjectStreamer();
	StXiMc::Class()->IgnoreTObjectStreamer();
	StKinkMc::Class()->IgnoreTObjectStreamer();
	#endif
	StMuMcVertex::Class()->IgnoreTObjectStreamer();
	StMuMcTrack::Class()->IgnoreTObjectStreamer();
	StMuTrack::Class()->IgnoreTObjectStreamer();
	StMuPrimaryVertex::Class()->IgnoreTObjectStreamer();
	// StDcaGeometry::Class()->IgnoreTObjectStreamer();
	StMuPrimaryTrackCovariance::Class()->IgnoreTObjectStreamer();
	StMuHelix::Class()->IgnoreTObjectStreamer();
	StMuEmcHit::Class()->IgnoreTObjectStreamer();
	StMuEmcTowerData::Class()->IgnoreTObjectStreamer();
	StMuPmdHit::Class()->IgnoreTObjectStreamer();
	StMuPmdCluster::Class()->IgnoreTObjectStreamer();
	EztEventHeader::Class()->IgnoreTObjectStreamer();
	EztTrigBlob::Class()->IgnoreTObjectStreamer();
	EztFpdBlob::Class()->IgnoreTObjectStreamer();
	EztEmcRawData::Class()->IgnoreTObjectStreamer();
	StMuFgtStrip::Class()->IgnoreTObjectStreamer();
	StMuFgtCluster::Class()->IgnoreTObjectStreamer();
	StMuFgtStripAssociation::Class()->IgnoreTObjectStreamer();
	StMuFgtAdc::Class()->IgnoreTObjectStreamer();
	}

star-sw/StRoot/StPicoDstMaker/StPicoDstMaker.cxx

Lines 227 to 250 in 25274b6

	void StPicoDstMaker::streamerOff() {
	// This is to to save space on the file. No need for TObject bits for this structure.
	// see: https://root.cern.ch/doc/master/classTClass.html#a606b0442d6fec4b1cd52f43bca73aa51
	StPicoEvent::Class()->IgnoreTObjectStreamer();
	StPicoTrack::Class()->IgnoreTObjectStreamer();
	StPicoBTofHit::Class()->IgnoreTObjectStreamer();
	StPicoBTowHit::Class()->IgnoreTObjectStreamer();
	StPicoMtdHit::Class()->IgnoreTObjectStreamer();
	StPicoBbcHit::Class()->IgnoreTObjectStreamer();
	StPicoEpdHit::Class()->IgnoreTObjectStreamer();
	StPicoFmsHit::Class()->IgnoreTObjectStreamer();
	StPicoBEmcSmdEHit::Class()->IgnoreTObjectStreamer();
	StPicoBEmcSmdPHit::Class()->IgnoreTObjectStreamer();
	StPicoEmcTrigger::Class()->IgnoreTObjectStreamer();
	StPicoMtdTrigger::Class()->IgnoreTObjectStreamer();
	StPicoBTofPidTraits::Class()->IgnoreTObjectStreamer();
	StPicoBEmcPidTraits::Class()->IgnoreTObjectStreamer();
	StPicoMtdPidTraits::Class()->IgnoreTObjectStreamer();
	StPicoTrackCovMatrix::Class()->IgnoreTObjectStreamer();
	StPicoETofHit::Class()->IgnoreTObjectStreamer();
	StPicoETofPidTraits::Class()->IgnoreTObjectStreamer();
	StPicoMcVertex::Class()->IgnoreTObjectStreamer();
	StPicoMcTrack::Class()->IgnoreTObjectStreamer();
	}

[genevb]

I consider the 2001 commit a hack on my part, so if it can be removed, that's a step in the right direction. And since I stopped maintaining this code something like 15 years ago, I don't feel protective of this code: please do whatever you need to. Thanks.

[klendathu2k]

It certainly looked like a duck and walked like a duck... and hack rhymes with quack, so good to have confirmation.

It may be an issue of timing, that ROOT6 needs to defer the call to suppress the TObject streamer until later (eg initialization time) rather than load time. I'll push that change shortly.

[plexoos]

In the context of this change I tried to understand the relation between MuDst and StrangeMuDst. It appears to me that the latter has become a part of MuDst long time ago. If this is the case, can we get rid of the __NO_STRANGE_MUDST__ branching in the code?

[klendathu2k]

@jdbrice @nigmatkulov Would appreciate reviews as code-owners.