DEventProcessor_mcthrown_tree.cc

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// $Id$
//
// File: DEventProcessor_mcthrown_tree.cc
// Created: Thu Sep 28 11:38:03 EDT 2011
// Creator: pmatt (on Darwin swire-b241.jlab.org 8.4.0 powerpc)
//

#include "DEventProcessor_mcthrown_tree.h"

#include <TAGGER/DTAGHGeometry.h>

// The executable should define the ROOTfile global variable. It will
// be automatically linked when dlopen is called.
extern TFile *ROOTfile;

// Routine used to create our DEventProcessor
extern "C"
{
   void InitPlugin(JApplication *app)
   {
      InitJANAPlugin(app);
      app->AddProcessor(new DEventProcessor_mcthrown_tree());
   }
} // "C"

//------------------
// init
//------------------
jerror_t DEventProcessor_mcthrown_tree::init(void)
{
   // require tagger hit for MCGEN beam photon by default to write event to TTree
   dTagCheck = true;
   gPARMS->SetDefaultParameter("MCTHROWN:TAGCHECK", dTagCheck);

   return NOERROR;
}

//------------------
// evnt
//------------------
jerror_t DEventProcessor_mcthrown_tree::evnt(JEventLoop *locEventLoop, uint64_t eventnumber)
{
   const DEventWriterROOT* locEventWriterROOT = NULL;
   locEventLoop->GetSingle(locEventWriterROOT);

   //This looks bad.  Really bad.  But relax, it's fine. 
   //This was previously in brun(), but brun() is ONLY CALLED BY ONE THREAD (no matter how many threads you run with!)
   //So this meant that the event writer wasn't set up for other threads!!
   //So, we call this here, every event, where every thread can see it. 
   //However, only the FIRST thread will actually create the tree
   //And, only the FIRST CALL for each thread will setup the event writer
   //Subsequent calls will auto-detect that everything is already done and bail early. 
   //Ugly, yes. But it works, and it's too late now to have each thread call brun().
   locEventWriterROOT->Create_ThrownTree(locEventLoop, "tree_thrown.root");

   // only keep generated events which hit a tagger counter
   vector<const DBeamPhoton*> locBeamPhotons;
   locEventLoop->Get(locBeamPhotons, "TAGGEDMCGEN");

   // skip events where generated beam photon did not hit TAGM or TAGH counter
   if(dTagCheck && locBeamPhotons.empty())
      return NOERROR;

   locEventWriterROOT->Fill_ThrownTree(locEventLoop);

   return NOERROR;
}