GlobalDataManagerExample.C

example macro on the use of QGlobalDataManager in the CINT/ROOT interpreter.

Author

Marco Vignati

 
{
    // using namespace Diana;
    // Avoid to put "Diana::" in front of diana objects.
    // This turns out to be mandatory in Cint since there are
    // problems with namespaces in conjunction with templates and
    // typedefs
    using namespace Diana;
    gSystem->Load("libqroot");
    // In diana there is a common instance  of QGlobalDataManager 
    // that is accessed via QBaseModule::GlobalData().
    // Here instead we have to create it. 
    QGlobalDataManager dm;
    // set the owner of the new QObjects that we will save
    // in diana this method is not accessible, and the owner is 
    // set to the current module being executed.
    dm.SetOwner("DataManagerTest");
    
    // Create two QVectors and save to file
    QVector vec(3),vec2(4);
    vec[0] = 1; vec[1] = 2; vec[2] = 3;
    vec2[0] = -1; vec2[1] = 0; vec2[2] = 1; vec2[3] = 2;
    // Create a GlobalHandle instance to manage each QVector
    // with the QGlobalDataManager. In the first we set Channel as key.
    GlobalHandle<QVector> hvec("MyQVector");
    hvec.SetChannel(3);
    hvec.Set(vec);
    dm.Set(&hvec,"dmtest.root");
    // In the second we set Run as key
    GlobalHandle<QVector> hvec2("MyQVector2");
    hvec2.SetRun(753);
    hvec2.Set(vec2);
    dm.Set(&hvec2,"dmtest.root");
 
    // Get RunData from DB and save it to file, owner will remain "DAQ".
    // since object is not modified.
    // The QRunData QObject has a specialized handle, the QRunDataHandle, 
    // that implements the specific DB queries
    QRunDataHandle rHandle(753);
    dm.Get("DAQ",&rHandle,"DB");
    dm.Set(&rHandle,"dmtest.txt");
 
    // Modify QRunData and set to file, owner will be "DataManagerTest" since we modified it.
    // We have to create a new handle, since each object needs its own handle
    QRunData newRunData = rHandle.Get();
    const int channel = newRunData.fBolometerChannels[0]; // modify sampling frequency of this channel;
    QChannelRunData chanRunData = newRunData.GetChannelRunData(channel);
    chanRunData.fSamplingFrequency = 250;
    newRunData.SetChannelRunData(channel,chanRunData);
    QRunDataHandle rHandle2(newRunData.fNumber);
    rHandle2.Set(newRunData);
    dm.Set(&rHandle2,"dmtest.root");
 
    // Write a TObject using a TObjectHandle onto a .root file
    TH1D histo("histo","My histogram",10,-5,5);
    histo.Fill(1.1);
    histo.Fill(3);
    QTObjectHandle<TH1D> hHandle("MyHisto");
    hHandle.SetChannel(3);
    hHandle.SetRun(753);
    hHandle.Set(histo);
    dm.Set(&hHandle,"dmtest.root");
 
    // print objects in cache
    dm.Dump(cout);
    
    cout<<"***** ATTENTION: Errors below are generated intentionally ******"<<endl;
    // Here we show how a write error appears
    QInt testInt = 2;
    GlobalHandle<QInt> intHandle2("MyFakeInt");
    intHandle2.Set(testInt);
    // if we are not root we have no write permissions
    dm.Set(&intHandle2,"/root/dianaglobal.root");
 
    // Here we show how a read error appears
    GlobalHandle<QInt> intHandle2("MyFakeInt2");
    dm.Get("MyFakeOwner",&intHandle2,"fakefile.txt");
    int myInt;
    //  the Get() call in the line below will abort the program
    //  since the object is not valid.
    myInt = intHandle2.Get();     
    // To not abort, comment the above line and handle the error as follows:
    if(!intHandle2.IsValid()) {
        cout<<intHandle2.GetError()<<endl;
    } else {
        myInt = intHandle2.Get();
    }
 
}