This section will guide you trough the steps necessary to perform simple analysis in a C++ analysis framework (psana). For more detailed description of psana consult Psana User Manual.
User modules in psana are the instances of the C++ class which must inherit from a special base class psana::Module
. There are several methods in the base class which can be overriden in the subclass (event() must always be implemented):
void beginJob(Env& env)
void beginRun(Env& env)
void beginCalibCycle(Env& env)
void event(Event& evt, Env& env)
void endCalibCycle(Env& env)
void endRun(Env& env)
void endJob(Env& env)
To start with the doing analysis one should have user release setup first as explained in Packages and Releases. If you have not done it yet create a package for your analysis with some unique name:
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newrel ana-current my_ana_rel # to make user release
cd my_ana_rel
sit_setup # never forget this!
newpkg my_ana_pkg # to make package for analysis code
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Good place to start writing analysis module is to create skeleton module from existing template:
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mkdir my_ana_pkg/src my_ana_pkg/include
codegen -l psana-module my_ana_pkg my_ana_mod
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This will create files my_ana_pkg/include/my_ana_mod.h
and my_ana_pkg/src/my_ana_mod.cpp
which you need to edit and fill with some useful code. Start your favorite editor:
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vi my_ana_pkg/src/my_ana_mod.cpp my_ana_pkg/include/my_ana_mod.h
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For example purposes we are going to use beam line data and print few interesting values on every event. For that the code will be quite simple (excluding comments):
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title | my_ana_pkg/include/my_ana_mod.h |
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#ifndef MY_ANA_PKG_MY_ANA_MOD_H
#define MY_ANA_PKG_MY_ANA_MOD_H
#include "psana/Module.h"
namespace my_ana_pkg {
class my_ana_mod : public Module {
public:
my_ana_mod (const std::string& name) ;
virtual ~my_ana_mod () ;
virtual void event(Event& evt, Env& env);
};
}
#endif // MY_ANA_PKG_MY_ANA_MOD_H
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title | my_ana_pkg/src/my_ana_mod.cpp |
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#include "my_ana_pkg/my_ana_mod.h"
#include "MsgLogger/MsgLogger.h"
#include "PSEvt/EventId.h"
#include "psddl_psana/bld.ddl.h"
// This declares this class as psana module
using namespace my_ana_pkg;
PSANA_MODULE_FACTORY(my_ana_mod)
namespace my_ana_pkg {
my_ana_mod::my_ana_mod (const std::string& name)
: Module(name)
{
}
my_ana_mod::~my_ana_mod ()
{
}
void
my_ana_mod::event(Event& evt, Env& env)
{
// get event time
PSTime::Time evtTime;
boost::shared_ptr<PSEvt::EventId> eventId = evt.get();
if (eventId.get()) {
evtTime = eventId->time();
}
// get beam data
boost::shared_ptr<Psana::Bld::BldDataEBeam> ebeam = evt.get(Source());
if (ebeam.get()) {
MsgLog(name(), info, "time: " << evtTime << ", charge: " << ebeam->ebeamCharge() <<
", energy: " << ebeam->ebeamL3Energy());
}
}
}
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