Detect and break reference loops. More...

#include <vtkGarbageCollector.h>

Inheritance diagram for vtkGarbageCollector:

Collaboration diagram for vtkGarbageCollector:

Public Types
typedef vtkObject	Superclass

Public Types inherited from vtkObject
typedef vtkObjectBase	Superclass

Public Member Functions
virtual int	IsA (const char *type)

vtkGarbageCollector *	NewInstance () const

void	PrintSelf (ostream &os, vtkIndent indent)

Public Member Functions inherited from vtkObject
vtkObject *	NewInstance () const

virtual void	DebugOn ()

virtual void	DebugOff ()

bool	GetDebug ()

void	SetDebug (bool debugFlag)

virtual void	Modified ()

virtual unsigned long	GetMTime ()

unsigned long	AddObserver (unsigned long event, vtkCommand *, float priority=0.0f)

unsigned long	AddObserver (const char event, vtkCommand , float priority=0.0f)

vtkCommand *	GetCommand (unsigned long tag)

void	RemoveObserver (vtkCommand *)

void	RemoveObservers (unsigned long event, vtkCommand *)

void	RemoveObservers (const char event, vtkCommand )

int	HasObserver (unsigned long event, vtkCommand *)

int	HasObserver (const char event, vtkCommand )

void	RemoveObserver (unsigned long tag)

void	RemoveObservers (unsigned long event)

void	RemoveObservers (const char *event)

void	RemoveAllObservers ()

int	HasObserver (unsigned long event)

int	HasObserver (const char *event)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(), float priority=0.0f)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, bool(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)

int	InvokeEvent (unsigned long event, void *callData)

int	InvokeEvent (const char event, void callData)

int	InvokeEvent (unsigned long event)

int	InvokeEvent (const char *event)

Public Member Functions inherited from vtkObjectBase
const char *	GetClassName () const

virtual void	Delete ()

virtual void	FastDelete ()

void	Print (ostream &os)

virtual void	Register (vtkObjectBase *o)

virtual void	UnRegister (vtkObjectBase *o)

void	SetReferenceCount (int)

void	PrintRevisions (ostream &)

virtual void	PrintHeader (ostream &os, vtkIndent indent)

virtual void	PrintTrailer (ostream &os, vtkIndent indent)

int	GetReferenceCount ()

Static Public Member Functions
static int	IsTypeOf (const char *type)

static vtkGarbageCollector *	SafeDownCast (vtkObjectBase *o)

static vtkGarbageCollector *	New ()

static void	Collect ()

static void	Collect (vtkObjectBase *root)


static void	DeferredCollectionPush ()

static void	DeferredCollectionPop ()


static void	SetGlobalDebugFlag (bool flag)

static bool	GetGlobalDebugFlag ()

Static Public Member Functions inherited from vtkObject
static int	IsTypeOf (const char *type)

static vtkObject *	SafeDownCast (vtkObjectBase *o)

static vtkObject *	New ()

static void	BreakOnError ()

static void	SetGlobalWarningDisplay (int val)

static void	GlobalWarningDisplayOn ()

static void	GlobalWarningDisplayOff ()

static int	GetGlobalWarningDisplay ()

Static Public Member Functions inherited from vtkObjectBase
static int	IsTypeOf (const char *name)

static vtkObjectBase *	New ()

Protected Member Functions
virtual vtkObjectBase *	NewInstanceInternal () const

	vtkGarbageCollector ()

	~vtkGarbageCollector ()

Protected Member Functions inherited from vtkObject
	vtkObject ()

virtual	~vtkObject ()

virtual void	RegisterInternal (vtkObjectBase *, int check)

virtual void	UnRegisterInternal (vtkObjectBase *, int check)

void	InternalGrabFocus (vtkCommand mouseEvents, vtkCommand keypressEvents=NULL)

void	InternalReleaseFocus ()

Protected Member Functions inherited from vtkObjectBase
	vtkObjectBase ()

virtual	~vtkObjectBase ()

virtual void	CollectRevisions (ostream &)

virtual void	ReportReferences (vtkGarbageCollector *)

	vtkObjectBase (const vtkObjectBase &)

void	operator= (const vtkObjectBase &)

Friends
class	vtkGarbageCollectorManager

class	vtkObjectBaseToGarbageCollectorFriendship

void VTKCOMMONCORE_EXPORT	vtkGarbageCollectorReportInternal (vtkGarbageCollector , vtkObjectBase , void , const char )

Additional Inherited Members
Protected Attributes inherited from vtkObject
bool	Debug

vtkTimeStamp	MTime

vtkSubjectHelper *	SubjectHelper

Protected Attributes inherited from vtkObjectBase
vtkAtomicInt32	ReferenceCount

vtkWeakPointerBase **	WeakPointers

Detailed Description

Detect and break reference loops.

vtkGarbageCollector is used by VTK classes that may be involved in reference counting loops (such as Algorithm <-> Executive). It detects strongly connected components of the reference graph that have been leaked deletes them. The garbage collector uses the ReportReferences method to search the reference graph and construct a net reference count for each connected component. If the net reference count is zero the entire set of objects is deleted. Deleting each component may leak other components, which are then collected recursively.

To enable garbage collection for a class, add these members:

public:
 virtual void Register(vtkObjectBase* o)
   {
   this->RegisterInternal(o, 1);
   }
 virtual void UnRegister(vtkObjectBase* o)
   {
   this->UnRegisterInternal(o, 1);
   }
protected:
 virtual void ReportReferences(vtkGarbageCollector* collector)
   {
   // Report references held by this object that may be in a loop.
   this->Superclass::ReportReferences(collector);
   vtkGarbageCollectorReport(collector, this->OtherObject, "Other Object");
   }

The implementations should be in the .cxx file in practice. It is important that the reference be reported using the real pointer or smart pointer instance that holds the reference. When collecting the garbage collector will actually set this pointer to NULL. The destructor of the class should be written to deal with this. It is also expected that an invariant is maintained for any reference that is reported. The variable holding the reference must always either be NULL or refer to a fully constructed valid object. Therefore code like "this->Object->UnRegister(this)" must be avoided if "this->Object" is a reported reference because it is possible that the object is deleted before UnRegister returns but then "this->Object" will be left as a dangling pointer. Instead use code like

vtkObjectBase* obj = this->Object;
this->Object = 0;
obj->UnRegister(this);

so that the reported reference maintains the invariant.

If subclassing from a class that already supports garbage collection, one need only provide the ReportReferences method.

Tests:: vtkGarbageCollector (Tests)

Definition at line 98 of file vtkGarbageCollector.h.

Member Typedef Documentation

typedef vtkObject vtkGarbageCollector::Superclass

Definition at line 101 of file vtkGarbageCollector.h.

Constructor & Destructor Documentation

vtkGarbageCollector::vtkGarbageCollector ( )

protected

vtkGarbageCollector::~vtkGarbageCollector ( )

protected

Member Function Documentation

static int vtkGarbageCollector::IsTypeOf ( const char * type )

static

virtual int vtkGarbageCollector::IsA ( const char * name )

virtual

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkObject.

static vtkGarbageCollector* vtkGarbageCollector::SafeDownCast ( vtkObjectBase * o )

static

virtual vtkObjectBase* vtkGarbageCollector::NewInstanceInternal ( ) const

protectedvirtual

Reimplemented from vtkObject.

vtkGarbageCollector* vtkGarbageCollector::NewInstance ( ) const

void vtkGarbageCollector::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)

virtual

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkObject.

static vtkGarbageCollector* vtkGarbageCollector::New ( )

static

static void vtkGarbageCollector::Collect ( )

static

Collect immediately using any objects whose collection was previously deferred as a root for the reference graph walk. Strongly connected components in the reference graph are identified. Those with a net reference count of zero are deleted. When a component is deleted it may remove references to other components that are not part of the same reference loop but are held by objects in the original component. These removed references are handled as any other and their corresponding checks may be deferred. This method keeps collecting until no deferred collection checks remain.

static void vtkGarbageCollector::Collect ( vtkObjectBase * root )

static

Collect immediately using the given object as the root for a reference graph walk. Strongly connected components in the reference graph are identified. Those with a net reference count of zero are deleted. When a component is deleted it may remove references to other components that are not part of the same reference loop but are held by objects in the original component. These removed references are handled as any other and their corresponding checks may be deferred. This method does continue collecting in this case.

static void vtkGarbageCollector::DeferredCollectionPush ( )

static

Push/Pop whether to do deferred collection. Whenever the total number of pushes exceeds the total number of pops collection will be deferred. Code can call the Collect method directly to force collection.

static void vtkGarbageCollector::DeferredCollectionPop ( )

static

Push/Pop whether to do deferred collection. Whenever the total number of pushes exceeds the total number of pops collection will be deferred. Code can call the Collect method directly to force collection.

static void vtkGarbageCollector::SetGlobalDebugFlag ( bool flag )

static

Set/Get global garbage collection debugging flag. When set to true, all garbage collection checks will produce debugging information.

static bool vtkGarbageCollector::GetGlobalDebugFlag ( )

static

Set/Get global garbage collection debugging flag. When set to true, all garbage collection checks will produce debugging information.

Friends And Related Function Documentation

friend class vtkGarbageCollectorManager

friend

Definition at line 169 of file vtkGarbageCollector.h.

friend class vtkObjectBaseToGarbageCollectorFriendship

friend

Definition at line 170 of file vtkGarbageCollector.h.

void VTKCOMMONCORE_EXPORT vtkGarbageCollectorReportInternal	(	vtkGarbageCollector *	,
		vtkObjectBase *	,
		void *	,
		const char *
	)

friend

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

/home/boeckb/code/depot/group-kitware/vtk/build-release/Utilities/Doxygen/dox/Common/Core/vtkGarbageCollector.h

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Friends

Additional Inherited Members

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation