v8::PersistentBase< T > Class Template Reference

#include <v8.h>

Inheritance diagram for v8::PersistentBase< T >:

Public Member Functions
V8_INLINE void	Reset ()
template<class S >
V8_INLINE void	Reset (Isolate *isolate, const Local< S > &other)
template<class S >
V8_INLINE void	Reset (Isolate *isolate, const PersistentBase< S > &other)
V8_INLINE bool	IsEmpty () const
V8_INLINE void	Empty ()
V8_INLINE Local< T >	Get (Isolate *isolate) const
template<class S >
V8_INLINE bool	operator== (const PersistentBase< S > &that) const
template<class S >
V8_INLINE bool	operator== (const Local< S > &that) const
template<class S >
V8_INLINE bool	operator!= (const PersistentBase< S > &that) const
template<class S >
V8_INLINE bool	operator!= (const Local< S > &that) const
template<typename P >
V8_INLINE void	SetWeak (P *parameter, typename WeakCallbackInfo< P >::Callback callback, WeakCallbackType type)
V8_INLINE void	SetWeak ()
template<typename P >
V8_INLINE P *	ClearWeak ()
V8_INLINE void	ClearWeak ()
V8_INLINE void	AnnotateStrongRetainer (const char *label)
V8_INLINE void	RegisterExternalReference (Isolate *isolate) const
	V8_DEPRECATE_SOON ("Objects are always considered independent. " "Use MarkActive to avoid collecting otherwise dead weak handles.", V8_INLINE void MarkIndependent())
V8_INLINE void	MarkActive ()
	V8_DEPRECATE_SOON ("See MarkIndependent.", V8_INLINE bool IsIndependent() const)
V8_INLINE bool	IsNearDeath () const
V8_INLINE bool	IsWeak () const
V8_INLINE void	SetWrapperClassId (uint16_t class_id)
V8_INLINE uint16_t	WrapperClassId () const
	PersistentBase (const PersistentBase &other)=delete
void	operator= (const PersistentBase &)=delete
template<class S >
void	Reset (Isolate *isolate, const Local< S > &other)
template<class S >
void	Reset (Isolate *isolate, const PersistentBase< S > &other)

Friends
class	Isolate
class	Utils
template<class F >
class	Local
template<class F1 , class F2 >
class	Persistent
template<class F >
class	Global
template<class F >
class	PersistentBase
template<class F >
class	ReturnValue
template<class F1 , class F2 , class F3 >
class	PersistentValueMapBase
template<class F1 , class F2 >
class	PersistentValueVector
class	Object

Detailed Description

template<class T>
class v8::PersistentBase< T >

An object reference that is independent of any handle scope. Where a Local handle only lives as long as the HandleScope in which it was allocated, a PersistentBase handle remains valid until it is explicitly disposed using Reset().

A persistent handle contains a reference to a storage cell within the V8 engine which holds an object value and which is updated by the garbage collector whenever the object is moved. A new storage cell can be created using the constructor or PersistentBase::Reset and existing handles can be disposed using PersistentBase::Reset.

Member Function Documentation

AnnotateStrongRetainer()

template<class T >

void v8::PersistentBase< T >::AnnotateStrongRetainer

(

const char *

label

)

Annotates the strong handle with the given label, which is then used by the heap snapshot generator as a name of the edge from the root to the handle. The function does not take ownership of the label and assumes that the label is valid as long as the handle is valid.

IsNearDeath()

template<class T >

bool v8::PersistentBase< T >::IsNearDeath

(

)

const

Checks if the handle holds the only reference to an object.

IsWeak()

template<class T >

bool v8::PersistentBase< T >::IsWeak

(

)

const

Returns true if the handle's reference is weak.

MarkActive()

template<class T >

void v8::PersistentBase< T >::MarkActive

(

)

Marks the reference to this object as active. The scavenge garbage collection should not reclaim the objects marked as active, even if the object held by the handle is otherwise unreachable.

This bit is cleared after the each garbage collection pass.

RegisterExternalReference()

template<class T >

void v8::PersistentBase< T >::RegisterExternalReference

(

Isolate *

isolate

)

const

Allows the embedder to tell the v8 garbage collector that a certain object is alive. Only allowed when the embedder is asked to trace its heap by EmbedderHeapTracer.

Reset() [1/3]

template<class T >

void v8::PersistentBase< T >::Reset

(

)

If non-empty, destroy the underlying storage cell IsEmpty() will return true after this call.

Reset() [2/3]

template<class T>

template<class S >

V8_INLINE void v8::PersistentBase< T >::Reset	(	Isolate *	isolate,
		const Local< S > &	other
	)

If non-empty, destroy the underlying storage cell and create a new one with the contents of other if other is non empty

Reset() [3/3]

template<class T>

template<class S >

V8_INLINE void v8::PersistentBase< T >::Reset	(	Isolate *	isolate,
		const PersistentBase< S > &	other
	)

If non-empty, destroy the underlying storage cell and create a new one with the contents of other if other is non empty

SetWeak() [1/2]

template<class T >

template<typename P >

V8_INLINE void v8::PersistentBase< T >::SetWeak	(	P *	parameter,
		typename WeakCallbackInfo< P >::Callback	callback,
		WeakCallbackType	type
	)

Install a finalization callback on this object. NOTE: There is no guarantee as to when or even if the callback is invoked. The invocation is performed solely on a best effort basis. As always, GC-based finalization should not be relied upon for any critical form of resource management!

SetWeak() [2/2]

template<class T >

void v8::PersistentBase< T >::SetWeak

(

)

Turns this handle into a weak phantom handle without finalization callback. The handle will be reset automatically when the garbage collector detects that the object is no longer reachable. A related function Isolate::NumberOfPhantomHandleResetsSinceLastCall returns how many phantom handles were reset by the garbage collector.

SetWrapperClassId()

template<class T >

void v8::PersistentBase< T >::SetWrapperClassId

(

uint16_t

class_id

)

Assigns a wrapper class ID to the handle. See RetainedObjectInfo interface description in v8-profiler.h for details.

V8_DEPRECATE_SOON()

template<class T>

v8::PersistentBase< T >::V8_DEPRECATE_SOON	(	"Objects are always considered independent. " "Use MarkActive to avoid collecting otherwise dead weak handles."	,
		V8_INLINE void	MarkIndependent()
	)

Marks the reference to this object independent. Garbage collector is free to ignore any object groups containing this object. Weak callback for an independent handle should not assume that it will be preceded by a global GC prologue callback or followed by a global GC epilogue callback.

WrapperClassId()

template<class T >

uint16_t v8::PersistentBase< T >::WrapperClassId

(

)

const

Returns the class ID previously assigned to this handle or 0 if no class ID was previously assigned.

---

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

• v8/include/v8.h