Class used internally to implement just-in-time reading. More...

Collaboration diagram for xAOD::TAuxStore::TBranchHandle:

Public Member Functions
	TBranchHandle (::Bool_t staticBranch, ::Bool_t primitiveBranch, const std::type_info ti, void obj, SG::auxid_t auxid, const std::string *prefix)
	Constructor. More...

::Int_t	getEntry ()
	Get entry from the branch that was loaded with TTree::LoadTree() More...

::TBranch **	branchPtr ()
	Get a pointer to the branch being held. More...

void *	objectPtr ()
	Get a pointer to the object. More...

void *	inputObjectPtr ()
	Get a pointer to the object (or its pointer) in memory for reading. More...

void *	outputObjectPtr ()
	Get a pointer to the object (or its pointer) in memory for writing. More...

const std::type_info *	typeInfo () const
	Get the type of the variable in memory. More...

void	reset ()
	Tell the object that the branch contents need to be re-read. More...

Private Attributes
::TBranch *	m_branch
	The branch that this object is handling. More...

::Long64_t	m_entry
	The last entry that was loaded for this branch. More...

void *	m_object
	The pointer to the object in memory. More...

::Bool_t	m_static
	Is this a static variable in question? More...

::Bool_t	m_primitive
	Is this a primitive variable? More...

const std::type_info *	m_typeInfo
	Type info for the variable. More...

::Bool_t	m_needsRead
	Read status flag. More...

SG::auxid_t	m_auxid
	The auxiliary ID of the branch. More...

const std::string *	m_prefix
	Pointer to the m_prefix string of the parent object. More...

Detailed Description

Class used internally to implement just-in-time reading.

This is a much simplified version of the code that we used in the D3PDReader code to read variables just in time for the users.

Definition at line 260 of file TAuxStore.h.

Constructor & Destructor Documentation

◆ TBranchHandle()

xAOD::TAuxStore::TBranchHandle::TBranchHandle	(	::Bool_t	staticBranch,
		::Bool_t	primitiveBranch,
		const std::type_info *	ti,
		void *	obj,
		SG::auxid_t	auxid,
		const std::string *	prefix
	)

Constructor.

Definition at line 1942 of file TAuxStore.cxx.

       : m_branch( 0 ), m_entry( 0 ) , m_object( obj ), m_static( staticBranch ),
         m_primitive( primitiveBranch ),
         m_typeInfo( ti ), m_needsRead( kTRUE ), m_auxid( auxid ),
         m_prefix( prefix ) {
    }

Member Function Documentation

◆ branchPtr()

TBranch ** xAOD::TAuxStore::TBranchHandle::branchPtr ( )

Get a pointer to the branch being held.

No magic here.

TTree::SetBranchAddress needs a pointer to a TBranch pointer. This function just makes sure that we can give it such a pointer, which will stay valid during the job.

Returns: A pointer to the branch object handled by this object

Definition at line 2039 of file TAuxStore.cxx.

                                                {
       return &m_branch;
    }

◆ getEntry()

Int_t xAOD::TAuxStore::TBranchHandle::getEntry ( )

Get entry from the branch that was loaded with TTree::LoadTree()

This function takes care of implementing just-in-time reading of branches for us.

Returns: The number of bytes read. A negative number in case of error.

Definition at line 1958 of file TAuxStore.cxx.

                                           {
  
       // A little sanity check:
       if( ! m_branch ) {
          // This is no longer an error. We can have such objects for
          // decorations, which don't exist on the input.
          return 0;
       }
  
       // Update the I/O monitoring:
       IOStats::instance().stats().readBranch( *m_prefix, m_auxid );
  
       // Make sure that the branch is associated to a tree 
       // as the entry to be read is retrieved from the tree
       if (!m_branch->GetTree()){
          Error("xAOD::TAuxStore::TBranchHandle::getEntry",
             XAOD_MESSAGE("Branch=%s is not associated to any tree while reading of branches within this class relies on that"),
             m_branch->GetName());
          return -1;
       }
  
       // Get the entry that should be read 
       // The entry to be read is set with TTree::LoadTree()
       // NB: for a branch from a friend tree and if the friend tree has an index built,
       // then the entry to read is found when calling the TTree::LoadTree() function 
       // that matches the major and minor values between the main tree and the friend tree 
       ::Long64_t entry = m_branch->GetTree()->GetReadEntry();
       
       if ( entry  < 0 ){
          // Raise error as it implies 
          // either that the TTree::LoadTree() function has not been called 
          // or 
          // the entry requested to be read by the user 
          // is not corresponding to any entry for the friend tree 
          Error("xAOD::TAuxStore::TBranchHandle::getEntry", 
             XAOD_MESSAGE( "Entry to read is not set for branch=%s from tree=%s. " 
             "It is either because TTree::LoadTree(entry) was not called "
             "beforehand in the TEvent class OR "
             "the entry requested to be read for the main tree is not corresponding to an event for the friend tree"), 
             m_branch->GetName(),
             m_branch->GetTree()->GetName());
          return -1;
       }
  
       // Check if anything needs to be done:
       if( ( entry == m_entry ) && ( ! m_needsRead ) ) {
          return 0;
       }
  
       // Switch the branch in the right mode:
       if( ! m_primitive ) {
          if( ( m_branch->GetMakeClass() != m_static ) &&
              ( ! m_branch->SetMakeClass( m_static ) ) ) {
             ::Error( "xAOD::TAuxStore::TBranchHandle::getEntry",
                      XAOD_MESSAGE( "Failed to call SetMakeClass(%i) on "
                                    "branch \"%s\"" ),
                      static_cast< int >( m_static ), m_branch->GetName() );
             return -1;
          }
       }
  
       // Load the entry.
       const ::Int_t nbytes = m_branch->GetEntry( entry );
  
       // If the load was successful, remember that we loaded this entry.
       if( nbytes >= 0 ) {
          m_entry = entry;
          // The reading will now be done:
          m_needsRead = kFALSE;
       }
  
       // Return the number of bytes read.
       return nbytes;
    }

◆ inputObjectPtr()

void * xAOD::TAuxStore::TBranchHandle::inputObjectPtr ( )

Get a pointer to the object (or its pointer) in memory for reading.

This is a tricky one.

When reading a single sub-branch of a branch that was written using an auxiliary container with direct ROOT I/O, TTree expects us to give it a simple pointer to the object that it should fill with content. But when reading a top level branch, like the dynamically created branches that we make, TTree needs to receive a pointer to a pointer.

Also, when reading a primitive type, ROOT also expects a simple pointer to the primitive variable in memory.

This function returns the correct kind of pointer for TTree::SetBranchAddress in all situations.

Returns: The pointer to be given to TTree::SetBranchAddress

Definition at line 2069 of file TAuxStore.cxx.

                                                 {
  
       // Return the correct pointer:
       if( m_static || m_primitive ) {
          return m_object;
       } else {
          return &m_object;
       }
    }

◆ objectPtr()

void * xAOD::TAuxStore::TBranchHandle::objectPtr ( )

Get a pointer to the object.

This function is used in the implementation of the IAuxStoreIO interface.

In there we just need a simple pointer to the object, we don't care about ROOT's idiosyncracies.

Returns: A pointer to the object in memory

Definition at line 2049 of file TAuxStore.cxx.

                                            {
  
       return m_object;
    }

◆ outputObjectPtr()

void * xAOD::TAuxStore::TBranchHandle::outputObjectPtr ( )

Get a pointer to the object (or its pointer) in memory for writing.

This is a slightly simplified version of GetInputObjectPtr(), for the case when we need to write a branch, and have to pass a pointer to TTree::Branch.

In this case we don't need to be mindful of whether the variable was read as a static or dynamic variable. The only interesting thing is if the variable is of a primitive or an object type.

Returns: The pointer to be given to TTree::Branch

Definition at line 2088 of file TAuxStore.cxx.

                                                  {
  
       // Return the correct pointer:
       if( m_primitive ) {
          return m_object;
       } else {
          return &m_object;
       }
    }

◆ reset()

void xAOD::TAuxStore::TBranchHandle::reset ( )

Tell the object that the branch contents need to be re-read.

After TEvent::Fill is called, the TAuxStore objects used for data writing are cleared.

Since TEvent doesn't know if the object is also used to read information or not. (If it's just used for writing, then this explicit clearing is mandatory.)

In case the user wants to continue processing the same event after the fill() call (because for instance the code is writing multiple trees), then we need to be aware that the variable needs to be re-read from the input to be in a good shape for the next write operation.

Definition at line 2114 of file TAuxStore.cxx.

                                       {
  
       m_needsRead = kTRUE;
       return;
    }

◆ typeInfo()

const std::type_info * xAOD::TAuxStore::TBranchHandle::typeInfo ( ) const

Get the type of the variable in memory.

Definition at line 2098 of file TAuxStore.cxx.

                                                               {
  
       return m_typeInfo;
    }

Member Data Documentation

◆ m_auxid

SG::auxid_t xAOD::TAuxStore::TBranchHandle::m_auxid

private

The auxiliary ID of the branch.

Definition at line 299 of file TAuxStore.h.

◆ m_branch

::TBranch* xAOD::TAuxStore::TBranchHandle::m_branch

private

The branch that this object is handling.

Definition at line 285 of file TAuxStore.h.

◆ m_entry

::Long64_t xAOD::TAuxStore::TBranchHandle::m_entry

private

The last entry that was loaded for this branch.

Definition at line 287 of file TAuxStore.h.

◆ m_needsRead

::Bool_t xAOD::TAuxStore::TBranchHandle::m_needsRead

private

Read status flag.

Definition at line 297 of file TAuxStore.h.

◆ m_object

void* xAOD::TAuxStore::TBranchHandle::m_object

private

The pointer to the object in memory.

Definition at line 289 of file TAuxStore.h.

◆ m_prefix

const std::string* xAOD::TAuxStore::TBranchHandle::m_prefix

private

Pointer to the m_prefix string of the parent object.

Definition at line 301 of file TAuxStore.h.

◆ m_primitive

::Bool_t xAOD::TAuxStore::TBranchHandle::m_primitive

private

Is this a primitive variable?

Definition at line 293 of file TAuxStore.h.

◆ m_static

::Bool_t xAOD::TAuxStore::TBranchHandle::m_static

private

Is this a static variable in question?

Definition at line 291 of file TAuxStore.h.

◆ m_typeInfo

const std::type_info* xAOD::TAuxStore::TBranchHandle::m_typeInfo

private

Type info for the variable.

Definition at line 295 of file TAuxStore.h.

The documentation for this class was generated from the following files:

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ TBranchHandle()

Member Function Documentation

◆ branchPtr()

◆ getEntry()

◆ inputObjectPtr()

◆ objectPtr()

◆ outputObjectPtr()

◆ reset()

◆ typeInfo()

Member Data Documentation

◆ m_auxid

◆ m_branch

◆ m_entry

◆ m_needsRead

◆ m_object

◆ m_prefix

◆ m_primitive

◆ m_static

◆ m_typeInfo