#include "TFile.h"
#include "TKey.h"
#include "TSystem.h"

Int_t loadRecursive(TDirectory *);

TFile *loadFileContent(const char *fn)
{
   // Initial memory usage
   ProcInfo_t pi0;
   gSystem->GetProcInfo(&pi0);

   // Open the file
   TFile *f = TFile::Open(fn);
   if (!f || f->IsZombie()) {
      SafeDelete(f);
      return (TFile *)0;
   }
   
   // Load recursively
   Int_t nobj = loadRecursive(f);
   
   // Final memory usage
   ProcInfo_t pi1;
   gSystem->GetProcInfo(&pi1);
   
   // Notify
   Printf("Footprint of file content (%d objects loaded): %ld kB (res), %ld KB (virt)",
                                      nobj, pi1.fMemResident - pi0.fMemResident,
                                      pi1.fMemVirtual - pi0.fMemVirtual);
   // Done
   return f;
}

Int_t loadRecursive(TDirectory *d)
{
   // Recursive load of the content of d.
   // Return number of objects read

   Int_t no = 0;
   TIter nxk(d->GetListOfKeys());
   TKey *k = 0;
   while ((k = (TKey *) nxk())) {
      TClass *cl = TClass::GetClass(k->GetClassName());
      if (cl->InheritsFrom("TDirectory")) {
         TDirectory *dr = (TDirectory *) k->ReadObj();
         no += loadRecursive(dr);
      } else {
         k->ReadObj();
         no++;
      }
   }
   // Done
   return no;
}