Detect and break reference loops. More...

#include <vtkGarbageCollector.h>

Inheritance diagram for vtkGarbageCollector:

Collaboration diagram for vtkGarbageCollector:

Public Types
typedef vtkObject	Superclass

Public Member Functions
virtual vtkTypeBool	IsA (const char *type)
	Return 1 if this class is the same type of (or a subclass of) the named class. More...

vtkGarbageCollector *	NewInstance () const

void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses. More...

Public Member Functions inherited from vtkObject
	vtkBaseTypeMacro (vtkObject, vtkObjectBase)

virtual void	DebugOn ()
	Turn debugging output on. More...

virtual void	DebugOff ()
	Turn debugging output off. More...

bool	GetDebug ()
	Get the value of the debug flag. More...

void	SetDebug (bool debugFlag)
	Set the value of the debug flag. More...

virtual void	Modified ()
	Update the modification time for this object. More...

virtual vtkMTimeType	GetMTime ()
	Return this object's modified time. More...

void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses. More...

void	RemoveObserver (unsigned long tag)

void	RemoveObservers (unsigned long event)

void	RemoveObservers (const char *event)

void	RemoveAllObservers ()

vtkTypeBool	HasObserver (unsigned long event)

vtkTypeBool	HasObserver (const char *event)

int	InvokeEvent (unsigned long event)

int	InvokeEvent (const char *event)

unsigned long	AddObserver (unsigned long event, vtkCommand *, float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

unsigned long	AddObserver (const char event, vtkCommand , float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkCommand *	GetCommand (unsigned long tag)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObserver (vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObservers (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObservers (const char event, vtkCommand )
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkTypeBool	HasObserver (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkTypeBool	HasObserver (const char event, vtkCommand )
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, bool(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)
	Allow user to set the AbortFlagOn() with the return value of the callback method. More...

int	InvokeEvent (unsigned long event, void *callData)
	This method invokes an event and return whether the event was aborted or not. More...

int	InvokeEvent (const char event, void callData)
	This method invokes an event and return whether the event was aborted or not. More...

Public Member Functions inherited from vtkObjectBase
const char *	GetClassName () const
	Return the class name as a string. More...

virtual void	Delete ()
	Delete a VTK object. More...

virtual void	FastDelete ()
	Delete a reference to this object. More...

void	InitializeObjectBase ()

void	Print (ostream &os)
	Print an object to an ostream. More...

virtual void	Register (vtkObjectBase *o)
	Increase the reference count (mark as used by another object). More...

virtual void	UnRegister (vtkObjectBase *o)
	Decrease the reference count (release by another object). More...

int	GetReferenceCount ()
	Return the current reference count of this object. More...

void	SetReferenceCount (int)
	Sets the reference count. More...

void	PrintRevisions (ostream &)
	Legacy. More...

virtual void	PrintHeader (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses. More...

virtual void	PrintTrailer (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses. More...

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

static vtkGarbageCollector *	SafeDownCast (vtkObjectBase *o)

static vtkGarbageCollector *	New ()

static void	Collect ()
	Collect immediately using any objects whose collection was previously deferred as a root for the reference graph walk. More...

static void	Collect (vtkObjectBase *root)
	Collect immediately using the given object as the root for a reference graph walk. More...


static void	DeferredCollectionPush ()
	Push/Pop whether to do deferred collection. More...

static void	DeferredCollectionPop ()
	Push/Pop whether to do deferred collection. More...


static void	SetGlobalDebugFlag (bool flag)
	Set/Get global garbage collection debugging flag. More...

static bool	GetGlobalDebugFlag ()
	Set/Get global garbage collection debugging flag. More...

Static Public Member Functions inherited from vtkObject
static vtkObject *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on. More...

static void	BreakOnError ()
	This method is called when vtkErrorMacro executes. More...

static void	SetGlobalWarningDisplay (int val)
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static void	GlobalWarningDisplayOn ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static void	GlobalWarningDisplayOff ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static int	GetGlobalWarningDisplay ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

Static Public Member Functions inherited from vtkObjectBase
static vtkTypeBool	IsTypeOf (const char *name)
	Return 1 if this class type is the same type of (or a subclass of) the named class. More...

static vtkObjectBase *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on. More...

Protected Member Functions
virtual vtkObjectBase *	NewInstanceInternal () const

	vtkGarbageCollector ()

	~vtkGarbageCollector () override

Protected Member Functions inherited from vtkObject
	vtkObject ()

	~vtkObject () override

void	RegisterInternal (vtkObjectBase *, vtkTypeBool check) override

void	UnRegisterInternal (vtkObjectBase *, vtkTypeBool check) override

void	InternalGrabFocus (vtkCommand mouseEvents, vtkCommand keypressEvents=nullptr)
	These methods allow a command to exclusively grab all events. More...

void	InternalReleaseFocus ()
	These methods allow a command to exclusively grab all events. More...

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:
 void Register(vtkObjectBase* o) override
   {
   this->RegisterInternal(o, true);
   }
 void UnRegister(vtkObjectBase* o) override
   {
   this->UnRegisterInternal(o, true);
   }
protected:
 void ReportReferences(vtkGarbageCollector* collector) override
   {
   // 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 nullptr. 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 nullptr 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 99 of file vtkGarbageCollector.h.

Member Typedef Documentation

typedef vtkObject vtkGarbageCollector::Superclass

Definition at line 102 of file vtkGarbageCollector.h.

Constructor & Destructor Documentation

vtkGarbageCollector::vtkGarbageCollector ( )

protected

vtkGarbageCollector::~vtkGarbageCollector ( )

overrideprotected

Member Function Documentation

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

static

virtual vtkTypeBool 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 vtkObjectBase.

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

static

virtual vtkObjectBase* vtkGarbageCollector::NewInstanceInternal ( ) const

protectedvirtual

vtkGarbageCollector* vtkGarbageCollector::NewInstance ( ) const

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

overridevirtual

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 vtkObjectBase.

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 185 of file vtkGarbageCollector.h.

friend class vtkObjectBaseToGarbageCollectorFriendship

friend

Definition at line 186 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/demarle/Source/VTK/release/8.2/build/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