cppgc::Visitor Class Reference

#include <visitor.h>

Inheritance diagram for cppgc::Visitor:

Classes
class	Key

Public Member Functions
	Visitor (Key)
virtual	~Visitor ()=default
template<typename T >
void	Trace (const Member< T > &member)
template<typename T >
void	Trace (const WeakMember< T > &weak_member)
template<typename T >
void	TraceMultiple (const subtle::UncompressedMember< T > *start, size_t len)
template<typename T , std::enable_if_t<!std::is_same_v< Member< T >, subtle::UncompressedMember< T > > > * = nullptr>
void	TraceMultiple (const Member< T > *start, size_t len)
template<typename T >
void	Trace (const T &object)
template<typename T >
void	TraceMultiple (const T *start, size_t len)
template<typename T , void(T::*)(const LivenessBroker &) method>
void	RegisterWeakCallbackMethod (const T *object)
template<typename K , typename V >
void	Trace (const EphemeronPair< K, V > &ephemeron_pair)
template<typename KeyType , typename ValueType >
void	TraceEphemeron (const WeakMember< KeyType > &weak_member_key, const Member< ValueType > *member_value)
template<typename KeyType , typename ValueType >
void	TraceEphemeron (const WeakMember< KeyType > &weak_member_key, const ValueType *value)
template<typename T >
void	TraceStrongly (const WeakMember< T > &weak_member)
template<typename T >
void	TraceStrongContainer (const T *object)
template<typename T >
void	TraceWeakContainer (const T *object, WeakCallback callback, const void *callback_data)
template<typename T >
void	RegisterMovableReference (const T **slot)
virtual void	RegisterWeakCallback (WeakCallback callback, const void *data)
virtual bool	DeferTraceToMutatorThreadIfConcurrent (const void *parameter, TraceCallback callback, size_t deferred_size)

Protected Member Functions
virtual void	Visit (const void *self, TraceDescriptor)
virtual void	VisitWeak (const void *self, TraceDescriptor, WeakCallback, const void *weak_member)
virtual void	VisitEphemeron (const void *key, const void *value, TraceDescriptor value_desc)
virtual void	VisitWeakContainer (const void *self, TraceDescriptor strong_desc, TraceDescriptor weak_desc, WeakCallback callback, const void *data)
virtual void	HandleMovableReference (const void **)
virtual void	VisitMultipleUncompressedMember (const void *start, size_t len, TraceDescriptorCallback get_trace_descriptor)

Friends
template<typename T , typename WeaknessPolicy , typename LocationPolicy , typename CheckingPolicy >
class	internal::BasicCrossThreadPersistent
template<typename T , typename WeaknessPolicy , typename LocationPolicy , typename CheckingPolicy >
class	internal::BasicPersistent
class	internal::ConservativeTracingVisitor
class	internal::VisitorBase

Detailed Description

Visitor passed to trace methods. All managed pointers must have called the Visitor's trace method on them.

class Foo final : public GarbageCollected<Foo> {
 public:
  void Trace(Visitor* visitor) const {
    visitor->Trace(foo_);
    visitor->Trace(weak_foo_);
  }
 private:
  Member<Foo> foo_;
  WeakMember<Foo> weak_foo_;
};

Constructor & Destructor Documentation

Visitor()

cppgc::Visitor::Visitor ( Key  )

inlineexplicit

~Visitor()

virtual cppgc::Visitor::~Visitor ( )

virtualdefault

Member Function Documentation

DeferTraceToMutatorThreadIfConcurrent()

virtual bool cppgc::Visitor::DeferTraceToMutatorThreadIfConcurrent ( const void *  parameter, TraceCallback  callback, size_t  deferred_size  )

inlinevirtual

Defers tracing an object from a concurrent thread to the mutator thread. Should be called by Trace methods of types that are not safe to trace concurrently.

Parameters

parameter	tells the trace callback which object was deferred.
callback	to be invoked for tracing on the mutator thread.
deferred_size	size of deferred object.

Returns

false if the object does not need to be deferred (i.e. currently traced on the mutator thread) and true otherwise (i.e. currently traced on a concurrent thread).

HandleMovableReference()

virtual void cppgc::Visitor::HandleMovableReference ( const void **  )

inlineprotectedvirtual

RegisterMovableReference()

template<typename T >

void cppgc::Visitor::RegisterMovableReference ( const T **  slot )

inline

Registers a slot containing a reference to an object allocated on a compactable space. Such references maybe be arbitrarily moved by the GC.

Parameters

slot	location of reference to object that might be moved by the GC. The slot must contain an uncompressed pointer.

RegisterWeakCallback()

virtual void cppgc::Visitor::RegisterWeakCallback ( WeakCallback  callback, const void *  data  )

inlinevirtual

Registers a weak callback that is invoked during garbage collection.

Parameters

callback	to be invoked.
data	custom data that is passed to the callback.

RegisterWeakCallbackMethod()

template<typename T , void(T::*)(const LivenessBroker &) method>

void cppgc::Visitor::RegisterWeakCallbackMethod ( const T *  object )

inline

Registers a weak callback method on the object of type T. See LivenessBroker for an usage example.

Parameters

object

of type T specifying a weak callback method.

Trace() [1/4]

template<typename K , typename V >

void cppgc::Visitor::Trace ( const EphemeronPair< K, V > &  ephemeron_pair )

inline

Trace method for EphemeronPair.

Parameters

ephemeron_pair

EphemeronPair reference weakly retaining a key object and strongly retaining a value object in case the key object is alive.

Trace() [2/4]

template<typename T >

void cppgc::Visitor::Trace ( const Member< T > &  member )

inline

Trace method for Member.

Parameters

member

Member reference retaining an object.

Trace() [3/4]

template<typename T >

void cppgc::Visitor::Trace ( const T &  object )

inline

Trace method for inlined objects that are not allocated themselves but otherwise follow managed heap layout and have a Trace() method.

Parameters

object

reference of the inlined object.

Trace() [4/4]

template<typename T >

void cppgc::Visitor::Trace ( const WeakMember< T > &  weak_member )

inline

Trace method for WeakMember.

Parameters

weak_member

WeakMember reference weakly retaining an object.

TraceEphemeron() [1/2]

template<typename KeyType , typename ValueType >

void cppgc::Visitor::TraceEphemeron ( const WeakMember< KeyType > &  weak_member_key, const Member< ValueType > *  member_value  )

inline

Trace method for a single ephemeron. Used for tracing a raw ephemeron in which the key and value are kept separately.

Parameters

weak_member_key	WeakMember reference weakly retaining a key object.
member_value	Member reference with ephemeron semantics.

TraceEphemeron() [2/2]

template<typename KeyType , typename ValueType >

void cppgc::Visitor::TraceEphemeron ( const WeakMember< KeyType > &  weak_member_key, const ValueType *  value  )

inline

Trace method for a single ephemeron. Used for tracing a raw ephemeron in which the key and value are kept separately. Note that this overload is for non-GarbageCollected values that can be traced though.

Parameters

key	WeakMember reference weakly retaining a key object.
value	Reference weakly retaining a value object. Note that ValueType here should not be Member. It is expected that TraceTrait<ValueType>::GetTraceDescriptor(value) returns a TraceDescriptor with a null base pointer but a valid trace method.

TraceMultiple() [1/3]

template<typename T , std::enable_if_t<!std::is_same_v< Member< T >, subtle::UncompressedMember< T > > > * = nullptr>

void cppgc::Visitor::TraceMultiple ( const Member< T > *  start, size_t  len  )

inline

TraceMultiple() [2/3]

template<typename T >

void cppgc::Visitor::TraceMultiple ( const subtle::UncompressedMember< T > *  start, size_t  len  )

inline

TraceMultiple() [3/3]

template<typename T >

void cppgc::Visitor::TraceMultiple ( const T *  start, size_t  len  )

inline

TraceStrongContainer()

template<typename T >

void cppgc::Visitor::TraceStrongContainer ( const T *  object )

inline

Trace method for retaining containers strongly.

Parameters

object

reference to the container.

TraceStrongly()

template<typename T >

void cppgc::Visitor::TraceStrongly ( const WeakMember< T > &  weak_member )

inline

Trace method that strongifies a WeakMember.

Parameters

weak_member

WeakMember reference retaining an object.

TraceWeakContainer()

template<typename T >

void cppgc::Visitor::TraceWeakContainer ( const T *  object, WeakCallback  callback, const void *  callback_data  )

inline

Trace method for retaining containers weakly. Note that weak containers should emit write barriers.

Parameters

object	reference to the container.
callback	to be invoked.
callback_data	custom data that is passed to the callback.

Visit()

virtual void cppgc::Visitor::Visit ( const void *  self, TraceDescriptor    )

inlineprotectedvirtual

VisitEphemeron()

virtual void cppgc::Visitor::VisitEphemeron ( const void *  key, const void *  value, TraceDescriptor  value_desc  )

inlineprotectedvirtual

VisitMultipleUncompressedMember()

virtual void cppgc::Visitor::VisitMultipleUncompressedMember ( const void *  start, size_t  len, TraceDescriptorCallback  get_trace_descriptor  )

inlineprotectedvirtual

Here is the call graph for this function:

VisitWeak()

virtual void cppgc::Visitor::VisitWeak ( const void *  self, TraceDescriptor  , WeakCallback  , const void *  weak_member  )

inlineprotectedvirtual

VisitWeakContainer()

virtual void cppgc::Visitor::VisitWeakContainer ( const void *  self, TraceDescriptor  strong_desc, TraceDescriptor  weak_desc, WeakCallback  callback, const void *  data  )

inlineprotectedvirtual

Friends And Related Function Documentation

internal::BasicCrossThreadPersistent

template<typename T , typename WeaknessPolicy , typename LocationPolicy , typename CheckingPolicy >

friend class internal::BasicCrossThreadPersistent

friend

internal::BasicPersistent

template<typename T , typename WeaknessPolicy , typename LocationPolicy , typename CheckingPolicy >

friend class internal::BasicPersistent

friend

internal::ConservativeTracingVisitor

friend class internal::ConservativeTracingVisitor

friend

internal::VisitorBase

friend class internal::VisitorBase

friend

---

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

• include/cppgc/visitor.h