Base class for converters for Root schema evolution. More...

#include <TVirtualConverter.h>

Inheritance diagram for TVirtualConverter:

Collaboration diagram for TVirtualConverter:

Public Member Functions
	TVirtualConverter (UInt_t checksum, TClass trans_cls, TClass pers_cls)
	Constructor, with checksum and class pointers.
	TVirtualConverter (TClass trans_cls, TClass pers_cls)
	Constructor, with class pointers.
	TVirtualConverter (UInt_t checksum, const std::string &trans_cls, const std::string &pers_cls)
	Constructor, with checksum and class names.
	TVirtualConverter (const std::string &trans_cls, const std::string &pers_cls)
	Constructor, with class names.
virtual	~TVirtualConverter ()
	Destructor.
TClass *	GetTransClass ()
	Return the transient class, to which we're converting.
TClass *	GetPersClass ()
	Return the persistent class, from which we're converting.
int	GetCheckSum () const
	Return the checksum of the class from which we're converting.
virtual void *	NewPersObj ()
	Create a new instance of the persistent class.
virtual void	DeletePersObj (void *persobj)
	Destroy an instance of the persistent class.
virtual void	ConvertVoid (void transobj, const void persobj)=0
	Do the conversion.
virtual void	ReadBuffer (TBuffer &b, void *obj, Version_t version, UInt_t R__S, UInt_t R__c)
	Read object in non-split mode.

Static Public Member Functions
static TClass *	ToClass (const std::string &name)
	Helper to convert a class name to a Root class pointer.
static TClass *	ToClass (const std::type_info &id)
	Helper to convert a `type_info` to a Root class pointer.

Protected Member Functions
	TVirtualConverter ()
	Default constructor.
void	SetCtorInfo (UInt_t checksum, TClass trans_cls, TClass pers_cls)
	Set the parameters that would normally be passed to the constructor.

Protected Attributes
void *	fPersObj
	The temporary persistent object instance, used for conversions (in non-split mode).

Private Member Functions
void	CheckStreamInfos ()
	Helper to allow for automatic schema evolution for persistent classes.
void	CheckClasses ()
	Helper to check that the classes have been defined properly.

Private Attributes
TClass *	fTransClass
	The declared transient class.
TClass *	fPersClass
	The declared persistent class.
UInt_t	fCheckSum
	The declared checksum.
int	fOldLast
	Used by `CheckStreamInfos:` the length of the streamerinfo list that we saw on the last `CheckStreamInfos` call.

Detailed Description

Base class for converters for Root schema evolution.

Derive from this and define the Convert method to do the conversion. You must specify both the transient and persistent classes in the constructor. The checksum must also be specified if the actual shape in the file is different than the provided persistent class.

Definition at line 109 of file TVirtualConverter.h.

Constructor & Destructor Documentation

◆ TVirtualConverter() [1/5]

TVirtualConverter::TVirtualConverter	(	UInt_t	checksum,
		TClass *	trans_cls,
		TClass *	pers_cls )

Constructor, with checksum and class pointers.

Parameters

checksum	The Root checksum of the persistent class we'll convert.
trans_cls	The transient class to which we will be converting.
pers_cls	The persistent class from which we will be converting.

Definition at line 110 of file TVirtualConverter.cxx.

  : fTransClass (trans_cls),
    fPersClass (pers_cls),
    fCheckSum (checksum),
    fOldLast (-3),
    fPersObj (nullptr)
{
  CheckClasses();
}

◆ TVirtualConverter() [2/5]

TVirtualConverter::TVirtualConverter	(	TClass *	trans_cls,
		TClass *	pers_cls )

Constructor, with class pointers.

Parameters

trans_cls	The transient class to which we will be converting.
pers_cls	The persistent class from which we will be converting.

The checksum will be calculated automatically from the provided classes.

Definition at line 130 of file TVirtualConverter.cxx.

  : fTransClass (trans_cls),
    fPersClass (pers_cls),
    fCheckSum (fTransClass ?
                 CalculateCheckSum (fPersClass, fTransClass->GetName()) : 0),
    fOldLast (-3),
    fPersObj (nullptr)
{
  CheckClasses();
}

◆ TVirtualConverter() [3/5]

TVirtualConverter::TVirtualConverter	(	UInt_t	checksum,
		const std::string &	trans_cls,
		const std::string &	pers_cls )

Constructor, with checksum and class names.

Parameters

checksum	The Root checksum of the persistent class we'll convert.
trans_cls	The name of the transient class to which we will be converting.
pers_cls	The name of the persistent class from which we will be converting.

Definition at line 151 of file TVirtualConverter.cxx.

  : fTransClass (ToClass (trans_cls)),
    fPersClass (ToClass (pers_cls)),
    fCheckSum (checksum),
    fOldLast (-3),
    fPersObj (nullptr)
{
  CheckClasses();
}

◆ TVirtualConverter() [4/5]

TVirtualConverter::TVirtualConverter	(	const std::string &	trans_cls,
		const std::string &	pers_cls )

Constructor, with class names.

Parameters

trans_cls	The name of the transient class to which we will be converting.
pers_cls	The name of the persistent class from which we will be converting.

The checksum will be calculated automatically from the provided classes.

Definition at line 173 of file TVirtualConverter.cxx.

  : fTransClass (ToClass (trans_cls)),
    fPersClass (ToClass (pers_cls)),
    fCheckSum (CalculateCheckSum (fPersClass, fTransClass->GetName())),
    fOldLast (-3),
    fPersObj (nullptr)
{
  CheckClasses();
}

◆ ~TVirtualConverter()

TVirtualConverter::~TVirtualConverter ( )

virtual

Destructor.

Definition at line 209 of file TVirtualConverter.cxx.

{
  // If we made an instance of the persistent class, get rid of it here.
  if (fPersObj)
    TVirtualConverter::DeletePersObj (fPersObj);
}

◆ TVirtualConverter() [5/5]

TVirtualConverter::TVirtualConverter ( )

protected

Default constructor.

Intended for use with T_AthenaRootConverter only! You must call SetCtorInfo after this!

Definition at line 412 of file TVirtualConverter.cxx.

  : fTransClass (nullptr),
    fPersClass (nullptr),
    fCheckSum (0),
    fOldLast (-3),
    fPersObj (nullptr)
{
}

Member Function Documentation

◆ CheckClasses()

void TVirtualConverter::CheckClasses ( )

private

Helper to check that the classes have been defined properly.

Check that the class pointers got defined.

Definition at line 188 of file TVirtualConverter.cxx.

{
  if (fTransClass == nullptr) {
    if (fPersClass == nullptr)
      Error ("TVirtualConverter",
             "Both transient and persistent classes are null.");
    else
      Error ("TVirtualConverter",
             "Transient class is null for persistent class `%s'",
             fPersClass->GetName());
  }
  else if (fPersClass == nullptr)
    Error ("TVirtualConverter",
           "Persistent class is null for transient class `%s'",
           fTransClass->GetName());
}

◆ CheckStreamInfos()

void TVirtualConverter::CheckStreamInfos ( )

private

Helper to allow for automatic schema evolution for persistent classes.

Automatic schema evolution doesn't work for persistent classes ‘out-of-the-box’ because we're reading the ‘persistent class’, but the relevant StreamerInfo stored in the file will have the name of the ‘transient class’.

This gets called each time we try to read an object (in non-split mode).

Definition at line 368 of file TVirtualConverter.cxx.

{
  // First check to see if the list of TStreamerInfo's for the transient
  // class has changed since the last time we were called.  If not,
  // then don't do anything.
  const TObjArray* trans_sis = fTransClass->GetStreamerInfos();
  if (trans_sis->GetLast() != fOldLast) {
    // There was a change.  Compare the TStreamerInfo list for the
    // persistent class and the transient class.  Look for entries
    // where the transient class has a TStreamerInfo but the persistent
    // class does not.
    //
    // Note: don't do this for `version' -1.
    // That should always be built from the internal dictionary.
    // (Otherwise, root can crash.)
    const TObjArray* pers_sis = fPersClass->GetStreamerInfos();
    assert (trans_sis->LowerBound() == pers_sis->LowerBound());
    for (Int_t v = trans_sis->LowerBound(); v <= trans_sis->GetLast(); ++v) {
      if (v != -1 &&
          trans_sis->At(v) != 0 &&
          (v > pers_sis->GetLast() || pers_sis->At(v) == 0))
      {
        // Ok, at this index, the transient class has a TStreamerInfo
        // but the persistent class does not.  Copy the TStreamerInfo
        // (changing the class that it applies to to the persistent
        // class), and add it to the persistent class's list.
        TStreamerInfo* new_si =(TStreamerInfo*)(trans_sis->At(v)->Clone());
        new_si->SetClass (fPersClass);
        fPersClass->RegisterStreamerInfo (new_si);
      }
    }
 
    // Remember how many entries there were in the list for next time.
    fOldLast = trans_sis->GetLast();
  }
}

◆ ConvertVoid()

virtual void TVirtualConverter::ConvertVoid	(	void *	transobj,
		const void *	persobj )

pure virtual

Do the conversion.

Parameters

transobj	Pointer to an instance of the transient class.
persobj	Pointer to an instance of the persistent class.

An implementation of this must be provided in derived classes. It should initialize the object at transobj from the one at persobj.

Implemented in TVirtualConverter_T< TTrans, TPers >, TVirtualConverter_T< Identifier, DetDescrCondIdentifier_old >, TVirtualConverter_T< TauJetContainer_p1, TauJetContainer_p1_old >, TVirtualConverter_T< TrigInDetTrackTruthMap, TrigInDetTrackTruthMap_old >, and TVirtualConverter_T< TrigSpacePointCounts_p1, TrigSpacePointCounts_p1_old >.

◆ DeletePersObj()

void TVirtualConverter::DeletePersObj ( void * persobj )

virtual

Destroy an instance of the persistent class.

Parameters

persobj Pointer to the instance to destroy.

The provided implementation of this uses TClass::Destructor, but you can override it if need be.

Definition at line 263 of file TVirtualConverter.cxx.

{
  return fPersClass->Destructor (persobj);
}

◆ GetCheckSum()

int TVirtualConverter::GetCheckSum ( ) const

Return the checksum of the class from which we're converting.

Definition at line 238 of file TVirtualConverter.cxx.

{
  return fCheckSum;
}

◆ GetPersClass()

TClass * TVirtualConverter::GetPersClass ( )

Return the persistent class, from which we're converting.

Definition at line 229 of file TVirtualConverter.cxx.

{
  return fPersClass;
}

◆ GetTransClass()

TClass * TVirtualConverter::GetTransClass ( )

Return the transient class, to which we're converting.

Definition at line 220 of file TVirtualConverter.cxx.

{
  return fTransClass;
}

◆ NewPersObj()

void * TVirtualConverter::NewPersObj ( )

virtual

Create a new instance of the persistent class.

The provided implementation of this uses TClass::New, but you can override it if need be.

Definition at line 250 of file TVirtualConverter.cxx.

{
  return fPersClass->New();
}

◆ ReadBuffer()

void TVirtualConverter::ReadBuffer	(	TBuffer &	b,
		void *	obj,
		Version_t	version,
		UInt_t	R__s,
		UInt_t	R__c )

virtual

Read object in non-split mode.

Parameters

b	The source of the data.
obj	The object into which we're reading. (This will be the transient object.)
version	The version number of the class.
R__s	The starting position in the buffer.
R__c	The number of bytes for this object in the buffer.

You normally shouldn't have to worry about this, but it's exposed here so that it can be overridden if needed. It's only used when reading in non-split mode.

Definition at line 282 of file TVirtualConverter.cxx.

{
  // Make sure that we've done automatic schema evolution on the
  // persistent side.
  CheckStreamInfos();
 
  // Make an instance of the persistent class, if we haven't done so already.
  if (fPersObj == nullptr)
    fPersObj = NewPersObj();
 
  // Read in the object, as an instance of the persistent class.
  fPersClass->ReadBuffer (b, fPersObj, version, R__s, R__c);
 
  // Convert to the transient representation.
  ConvertVoid (obj, fPersObj);
}

◆ SetCtorInfo()

void TVirtualConverter::SetCtorInfo	(	UInt_t	checksum,
		TClass *	trans_cls,
		TClass *	pers_cls )

protected

Set the parameters that would normally be passed to the constructor.

Parameters

checksum	The Root checksum of the persistent class we'll convert.
trans_cls	The transient class to which we will be converting.
pers_cls	The persistent class from which we will be converting.

Intended for use with T_AthenaRootConverter only!

Definition at line 430 of file TVirtualConverter.cxx.

{
  assert (fTransClass == nullptr);
 
  fCheckSum = checksum;
  fTransClass = trans_cls;
  fPersClass = pers_cls;
  CheckClasses();
}

◆ ToClass() [1/2]

TClass * TVirtualConverter::ToClass ( const std::string & name )

static

Helper to convert a class name to a Root class pointer.

Parameters

name	The name of the class to convert.

Returns nullptr on failure.

Definition at line 310 of file TVirtualConverter.cxx.

{
  return gROOT->GetClass (name.c_str());
}

◆ ToClass() [2/2]

TClass * TVirtualConverter::ToClass ( const std::type_info & id )

static

Helper to convert a type_info to a Root class pointer.

Parameters

name	The `type_info` of the class to convert.

Returns nullptr on failure.

Definition at line 322 of file TVirtualConverter.cxx.

{
  TClass* cl = gROOT->GetClass (id);
  if (cl) return cl;
 
  // This may fail if the dictionary hasn't been loaded yet,
  // since we can auto-load only on the name.
  // Make some attempt to get a name from the type_info.
  const char* name = id.name();
  cl = gROOT->GetClass (name);
  if (cl) return cl;
 
  const char* n2 = name;
  while (isdigit(*n2))
    ++n2;
  cl = gROOT->GetClass (n2);
  if (cl) return cl;
 
  int errorCode = 0;
  char* demname = nullptr;
  {
    // Protect against data race inside TClassEdit.
    // https://github.com/root-project/root/issues/10353
    // Should be fixed in root 6.26.02.
    R__WRITE_LOCKGUARD(ROOT::gCoreMutex);
    demname = TClassEdit::DemangleTypeIdName (id, errorCode);
  }
  if (demname) {
    cl = gROOT->GetClass (demname);
    free (demname);
  }
  return cl;
}

Member Data Documentation

◆ fCheckSum

UInt_t TVirtualConverter::fCheckSum

private

The declared checksum.

Definition at line 261 of file TVirtualConverter.h.

◆ fOldLast

int TVirtualConverter::fOldLast

private

Used by CheckStreamInfos: the length of the streamerinfo list that we saw on the last CheckStreamInfos call.

Definition at line 265 of file TVirtualConverter.h.

◆ fPersClass

TClass* TVirtualConverter::fPersClass

private

The declared persistent class.

Definition at line 258 of file TVirtualConverter.h.

◆ fPersObj

void* TVirtualConverter::fPersObj

protected

The temporary persistent object instance, used for conversions (in non-split mode).

Definition at line 271 of file TVirtualConverter.h.

◆ fTransClass

TClass* TVirtualConverter::fTransClass

private

The declared transient class.

Definition at line 255 of file TVirtualConverter.h.

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

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ TVirtualConverter() [1/5]

◆ TVirtualConverter() [2/5]

◆ TVirtualConverter() [3/5]

◆ TVirtualConverter() [4/5]

◆ ~TVirtualConverter()

◆ TVirtualConverter() [5/5]

Member Function Documentation

◆ CheckClasses()

◆ CheckStreamInfos()

◆ ConvertVoid()

◆ DeletePersObj()

◆ GetCheckSum()

◆ GetPersClass()

◆ GetTransClass()

◆ NewPersObj()

◆ ReadBuffer()

◆ SetCtorInfo()

◆ ToClass() [1/2]

◆ ToClass() [2/2]

Member Data Documentation

◆ fCheckSum

◆ fOldLast

◆ fPersClass

◆ fPersObj

◆ fTransClass