[MFT] Move static arrays to be initialized before the processing starts

[robincaron13]

To follow PR#10654, here the arrays are kept as static member and are moved to the tracker class to be initialized before the processing starts (not sure if it was what you were thinking @shahor02)

[shahor02]

Hi @robincaron13
Thanks for taking care, but this not what I meant: moving the static array from the base class to the derived one will change nothing: it will still be allocated w/o the creation of the actual object, i.e. in any process which links to this library.
Instead, I would define in the TrackerConfig.h

using BinContainer = std::array<std::array<std::array<std::vector<Int_t>, constants::index_table::MaxRPhiBins>, (constants::mft::LayersNumber - 1)>, (constants::mft::LayersNumber - 1)>;

static std_unique_ptr<BinContainer> mBins;
static std_unique_ptr<BinContainer> mBinsS;
static initBinContainers() { // implementation can go to cxx file
  if (!mBins) {
    mBins = std::make_unique<BinContainer>();
    initBins(mBins.get()); // init bins with static method. If not possible to do using static method, then make this method non-static and lock the code by mutex.
   //
  }
  // same for mBinsS
}

In the TrackerSpec call this initBinContainers before instantiating the trackers (e.g. in its init method (or in the beginning of updateTimeDependentParams) if this method can be static.
Otherwise, put the non-static method (protected by mutex) in the Tracker constructed.
Same for destroying arrays via mBins.reset() : do this either in the Tracker destructor of the protecting the call with mutex or in the TrackerSpec destructor.

For the usage of the mutex see e.g. how the

AliceO2/Detectors/Base/include/DetectorsBase/GeometryManager.h

Line 140 in 816da25

static std::mutex sTGMutex;

is used in

AliceO2/Detectors/Base/src/GeometryManager.cxx

Lines 37 to 48 in 816da25

	std::mutex GeometryManager::sTGMutex;
	//______________________________________________________________________
	Bool_t GeometryManager::getOriginalMatrix(const char* symname, TGeoHMatrix& m)
	{
	m.Clear();
	if (!gGeoManager || !gGeoManager->IsClosed()) {
	LOG(error) << "No active geometry or geometry not yet closed!";
	;
	return kFALSE;
	}
	std::lock_guard<std::mutex> guard(sTGMutex);

and below.

[robincaron13]

Hi @shahor02,

Thanks a lot for your answer and your proposal.
Currently I'm making the changes but I have a question regarding the initBins. What should contain this function exactly? Because from my understanding an arrays is intialized at the moment we define its size but here it's now about std::unique_ptr, also I tried different way like for example using std::unique_ptr<BinContainer>(new BinContainer) and no success... Sorry I'm not an expert in the use of some functionalities in c++.

[shahor02]

I have a question regarding the initBins. What should contain this function exactly?
Hi @robincaron13
The initialization of the uniqe_ptr will just allocate the memory but not assign the values you need.
The initBins should contain what

AliceO2/Detectors/ITSMFT/MFT/tracking/src/Tracker.cxx

Lines 198 to 214 in 50d8566

	mBinsS[layer1][layer2 - 1][binIndex1].emplace_back(binIndex2S);
	}
	}
	int binwPhi = mPhiBinWin[layer2];
	int binhwPhi = binwPhi / 2;
	for (Int_t binR = rBinMin; binR <= rBinMax; ++binR) {
	for (Int_t iPhi = 0; iPhi < binwPhi; ++iPhi) {
	int binPhi = binPhi_proj + (iPhi - binhwPhi);
	if (binPhi < 0) {
	continue;
	}
	binIndex2 = getBinIndex(binR, binPhi);
	mBins[layer1][layer2 - 1][binIndex1].emplace_back(binIndex2);

does: assignment of the values.
I did not check if

AliceO2/Detectors/ITSMFT/MFT/tracking/src/Tracker.cxx

Line 109 in 50d8566

void Tracker<T>::initializeFinder()

does anything else but setting mBins(S) values, if this function should be called only once before the processing starts, then this is actually the "initBins" I meant.

[robincaron13]

Hi @shahor02,

Thanks for your answer. Some modifications are pushed according to your comments.
For the moment I still kept a dummy static initBins in the TrackerConfig.cxx to do nothing, also basically the initBinConntainer is just doing mBins = std::make_unique<BinContainer>(); and it should be called once in the init of the TrackerSpec.cxx. The mBins.reset() is called through the new destructor called in TrackerSpec.cxx. The mutex is also added to the intializeFinder funnction where the assignment of the mBins values are perfomed.
Let me know if it goes in the good direction, or there are still modifications to do.

[shahor02]

Thanks @robincaron13
In general ok, but please see some comments below.

[robincaron13]

Hi @shahor02
Let me know if the last changes added were fine with you. Thanks.

[shahor02]

thanks, looks good