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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsCycleCollectionParticipant_h__
#define nsCycleCollectionParticipant_h__
#include <type_traits>
#include "js/HeapAPI.h"
#include "js/TypeDecls.h"
#include "mozilla/MacroForEach.h"
#include "nsCycleCollectionNoteChild.h"
#include "nsDebug.h"
#include "nsID.h"
#include "nscore.h"
/**
* Note: the following two IIDs only differ in one bit in the last byte. This
* is a hack and is intentional in order to speed up the comparison inside
* NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION_INHERITED.
*/
#define NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID \
{ \
0xc61eac14, 0x5f7a, 0x4481, { \
0x96, 0x5e, 0x7e, 0xaa, 0x6e, 0xff, 0xa8, 0x5e \
} \
}
/**
* Special IID to get at the base nsISupports for a class. Usually this is the
* canonical nsISupports pointer, but in the case of tearoffs for example it is
* the base nsISupports pointer of the tearoff. This allow the cycle collector
* to have separate nsCycleCollectionParticipant's for tearoffs or aggregated
* classes.
*/
#define NS_CYCLECOLLECTIONISUPPORTS_IID \
{ \
0xc61eac14, 0x5f7a, 0x4481, { \
0x96, 0x5e, 0x7e, 0xaa, 0x6e, 0xff, 0xa8, 0x5f \
} \
}
/**
* Just holds the IID so NS_GET_IID works.
*/
class nsCycleCollectionISupports {
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_CYCLECOLLECTIONISUPPORTS_IID)
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsCycleCollectionISupports,
NS_CYCLECOLLECTIONISUPPORTS_IID)
class nsCycleCollectionTraversalCallback;
class nsISupports;
class nsWrapperCache;
namespace JS {
template <class T>
class Heap;
template <typename T>
class TenuredHeap;
} /* namespace JS */
/*
* A struct defining pure virtual methods which are called when tracing cycle
* collection paticipants. The appropriate method is called depending on the
* type of JS GC thing.
*/
struct TraceCallbacks {
virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(nsWrapperCache* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
void* aClosure) const = 0;
virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
void* aClosure) const = 0;
};
/*
* An implementation of TraceCallbacks that calls a single function for all JS
* GC thing types encountered. Implemented in
* nsCycleCollectorTraceJSHelpers.cpp.
*/
struct TraceCallbackFunc : public TraceCallbacks {
typedef void (*Func)(JS::GCCellPtr aPtr, const char* aName, void* aClosure);
explicit TraceCallbackFunc(Func aCb) : mCallback(aCb) {}
virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(nsWrapperCache* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
void* aClosure) const override;
virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
void* aClosure) const override;
private:
Func mCallback;
};
/**
* Participant implementation classes
*/
class NS_NO_VTABLE nsCycleCollectionParticipant {
public:
using Flags = uint8_t;
static constexpr Flags FlagMightSkip = 1u << 0;
static constexpr Flags FlagTraverseShouldTrace = 1u << 1;
static constexpr Flags FlagMultiZoneJSHolder = 1u << 2;
static constexpr Flags AllFlags =
FlagMightSkip | FlagTraverseShouldTrace | FlagMultiZoneJSHolder;
constexpr explicit nsCycleCollectionParticipant(Flags aFlags)
: mFlags(aFlags) {
MOZ_ASSERT((aFlags & ~AllFlags) == 0);
}
NS_IMETHOD TraverseNative(void* aPtr,
nsCycleCollectionTraversalCallback& aCb) = 0;
nsresult TraverseNativeAndJS(void* aPtr,
nsCycleCollectionTraversalCallback& aCb) {
nsresult rv = TraverseNative(aPtr, aCb);
if (TraverseShouldTrace()) {
// Note, we always call Trace, even if Traverse returned
// NS_SUCCESS_INTERRUPTED_TRAVERSE.
TraceCallbackFunc noteJsChild(&nsCycleCollectionParticipant::NoteJSChild);
Trace(aPtr, noteJsChild, &aCb);
}
return rv;
}
// Implemented in nsCycleCollectorTraceJSHelpers.cpp.
static void NoteJSChild(JS::GCCellPtr aGCThing, const char* aName,
void* aClosure);
NS_IMETHOD_(void) Root(void* aPtr) = 0;
NS_IMETHOD_(void) Unlink(void* aPtr) = 0;
NS_IMETHOD_(void) Unroot(void* aPtr) = 0;
NS_IMETHOD_(const char*) ClassName() = 0;
NS_IMETHOD_(void)
Trace(void* aPtr, const TraceCallbacks& aCb, void* aClosure) {}
// CanSkip is called during nsCycleCollector_forgetSkippable. If it returns
// true, aPtr is removed from the purple buffer and therefore might be left
// out from the cycle collector graph the next time that's constructed (unless
// it's reachable in some other way).
//
// CanSkip is allowed to expand the set of certainly-alive objects by removing
// other objects from the purple buffer, marking JS things black (in the GC
// sense), and so forth. Furthermore, if aRemovingAllowed is true, this call
// is allowed to remove aPtr itself from the purple buffer.
//
// Things can return true from CanSkip if either they know they have no
// outgoing edges at all in the cycle collection graph (because then they
// can't be parts of a cycle) or they know for sure they're alive.
bool CanSkip(void* aPtr, bool aRemovingAllowed) {
return MightSkip() ? CanSkipReal(aPtr, aRemovingAllowed) : false;
}
// CanSkipInCC is called during construction of the initial set of roots for
// the cycle collector graph. If it returns true, aPtr is left out of that
// set of roots. Note that the set of roots includes whatever is in the
// purple buffer (after earlier CanSkip calls) plus various other sources of
// roots, so an object can end up having CanSkipInCC called on it even if it
// returned true from CanSkip. One example of this would be an object that
// can potentially trace JS things.
//
// CanSkipInCC is allowed to remove other objects from the purple buffer but
// should not remove aPtr and should not mark JS things black. It should also
// not modify any reference counts.
//
// Things can return true from CanSkipInCC if either they know they have no
// outgoing edges at all in the cycle collection graph or they know for sure
// they're alive _and_ none of their outgoing edges are to gray (in the GC
// sense) gcthings. See also nsWrapperCache::HasNothingToTrace and
// nsWrapperCache::HasKnownLiveWrapperAndDoesNotNeedTracing. The restriction
// on not having outgoing edges to gray gcthings is because if we _do_ have
// them that means we have a "strong" edge to a JS thing and since we're alive
// we need to trace through it and mark keep them alive. Outgoing edges to
// C++ things don't matter here, because the criteria for when a CC
// participant is considered alive are slightly different for JS and C++
// things: JS things are only considered alive when reachable via an edge from
// a live thing, while C++ things are also considered alive when their
// refcount exceeds the number of edges via which they are reachable.
bool CanSkipInCC(void* aPtr) {
return MightSkip() ? CanSkipInCCReal(aPtr) : false;
}
// CanSkipThis is called during construction of the cycle collector graph,
// when we traverse an edge to aPtr and consider adding it to the graph. If
// it returns true, aPtr is not added to the graph.
//
// CanSkipThis is not allowed to change the liveness or reference count of any
// objects.
//
// Things can return true from CanSkipThis if either they know they have no
// outgoing edges at all in the cycle collection graph or they know for sure
// they're alive.
//
// Note that CanSkipThis doesn't have to worry about outgoing edges to gray GC
// things, because if this object could have those it already got added to the
// graph during root set construction. An object should never have
// CanSkipThis called on it if it has outgoing strong references to JS things.
bool CanSkipThis(void* aPtr) {
return MightSkip() ? CanSkipThisReal(aPtr) : false;
}
NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) = 0;
bool IsMultiZoneJSHolder() const { return mFlags & FlagMultiZoneJSHolder; }
protected:
NS_IMETHOD_(bool) CanSkipReal(void* aPtr, bool aRemovingAllowed) {
NS_ASSERTION(false, "Forgot to implement CanSkipReal?");
return false;
}
NS_IMETHOD_(bool) CanSkipInCCReal(void* aPtr) {
NS_ASSERTION(false, "Forgot to implement CanSkipInCCReal?");
return false;
}
NS_IMETHOD_(bool) CanSkipThisReal(void* aPtr) {
NS_ASSERTION(false, "Forgot to implement CanSkipThisReal?");
return false;
}
private:
bool MightSkip() const { return mFlags & FlagMightSkip; }
bool TraverseShouldTrace() const { return mFlags & FlagTraverseShouldTrace; }
const Flags mFlags;
};
class NS_NO_VTABLE nsScriptObjectTracer : public nsCycleCollectionParticipant {
public:
constexpr explicit nsScriptObjectTracer(Flags aFlags)
: nsCycleCollectionParticipant(aFlags | FlagTraverseShouldTrace) {}
NS_IMETHOD_(void)
Trace(void* aPtr, const TraceCallbacks& aCb, void* aClosure) override = 0;
};
class NS_NO_VTABLE nsXPCOMCycleCollectionParticipant
: public nsScriptObjectTracer {
public:
constexpr explicit nsXPCOMCycleCollectionParticipant(Flags aFlags)
: nsScriptObjectTracer(aFlags) {}
NS_DECLARE_STATIC_IID_ACCESSOR(NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
NS_IMETHOD_(void) Root(void* aPtr) override;
NS_IMETHOD_(void) Unroot(void* aPtr) override;
NS_IMETHOD_(void)
Trace(void* aPtr, const TraceCallbacks& aCb, void* aClosure) override;
static bool CheckForRightISupports(nsISupports* aSupports);
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsXPCOMCycleCollectionParticipant,
NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing a QI to nsXPCOMCycleCollectionParticipant
///////////////////////////////////////////////////////////////////////////////
#define NS_CYCLE_COLLECTION_CLASSNAME(_class) \
_class::NS_CYCLE_COLLECTION_INNERCLASS
// The IIDs for nsXPCOMCycleCollectionParticipant and nsCycleCollectionISupports
// are special in that they only differ in their last byte. This allows for the
// optimization below where we first check the first three words of the IID and
// if we find a match we check the last word to decide which case we have to
// deal with.
#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class) \
if (TopThreeWordsEquals( \
aIID, NS_GET_IID(nsXPCOMCycleCollectionParticipant), \
NS_GET_IID( \
nsCycleCollectionISupports)) && /* The calls to LowWordEquals \
here are repeated inside the \
if branch. This is due to the \
fact that we need to maintain \
the if/else chain for these \
macros, so that the control \
flow never enters the if \
branch unless if we're \
certain one of the \
LowWordEquals() branches will \
get executed. */ \
(LowWordEquals(aIID, NS_GET_IID(nsXPCOMCycleCollectionParticipant)) || \
LowWordEquals(aIID, NS_GET_IID(nsCycleCollectionISupports)))) { \
if (LowWordEquals(aIID, NS_GET_IID(nsXPCOMCycleCollectionParticipant))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class); \
return NS_OK; \
} \
if (LowWordEquals(aIID, NS_GET_IID(nsCycleCollectionISupports))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
return NS_OK; \
} \
/* Avoid warnings about foundInterface being left uninitialized. */ \
foundInterface = nullptr; \
} else
#define NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(_class) \
NS_INTERFACE_MAP_BEGIN(_class) \
NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
#define NS_INTERFACE_TABLE_TO_MAP_SEGUE_CYCLE_COLLECTION(_class) \
if (rv == NS_OK) return rv; \
nsISupports* foundInterface; \
NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
// The IIDs for nsXPCOMCycleCollectionParticipant and nsCycleCollectionISupports
// are special in that they only differ in their last byte. This allows for the
// optimization below where we first check the first three words of the IID and
// if we find a match we check the last word to decide which case we have to
// deal with.
#define NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION_INHERITED(_class) \
NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr) { \
MOZ_ASSERT(aInstancePtr, "null out param"); \
\
if (TopThreeWordsEquals(aIID, \
NS_GET_IID(nsXPCOMCycleCollectionParticipant), \
NS_GET_IID(nsCycleCollectionISupports))) { \
if (LowWordEquals(aIID, \
NS_GET_IID(nsXPCOMCycleCollectionParticipant))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class); \
return NS_OK; \
} \
if (LowWordEquals(aIID, NS_GET_IID(nsCycleCollectionISupports))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
return NS_OK; \
} \
} \
nsresult rv = NS_ERROR_FAILURE;
#define NS_CYCLE_COLLECTION_UPCAST(obj, clazz) \
NS_CYCLE_COLLECTION_CLASSNAME(clazz)::Upcast(obj)
#ifdef DEBUG
# define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr) _ptr->CheckForRightParticipant()
#else
# define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr)
#endif
// The default implementation of this class template is empty, because it
// should never be used: see the partial specializations below.
template <typename T, bool IsXPCOM = std::is_base_of<nsISupports, T>::value>
struct DowncastCCParticipantImpl {};
// Specialization for XPCOM CC participants
template <typename T>
struct DowncastCCParticipantImpl<T, true> {
static T* Run(void* aPtr) {
nsISupports* s = static_cast<nsISupports*>(aPtr);
MOZ_ASSERT(NS_CYCLE_COLLECTION_CLASSNAME(T)::CheckForRightISupports(s),
"not the nsISupports pointer we expect");
T* rval = NS_CYCLE_COLLECTION_CLASSNAME(T)::Downcast(s);
NS_CHECK_FOR_RIGHT_PARTICIPANT(rval);
return rval;
}
};
// Specialization for native CC participants
template <typename T>
struct DowncastCCParticipantImpl<T, false> {
static T* Run(void* aPtr) { return static_cast<T*>(aPtr); }
};
template <typename T>
T* DowncastCCParticipant(void* aPtr) {
return DowncastCCParticipantImpl<T>::Run(aPtr);
}
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing CanSkip methods
///////////////////////////////////////////////////////////////////////////////
// See documentation for nsCycleCollectionParticipant::CanSkip for documentation
// about this method.
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(_class) \
NS_IMETHODIMP_(bool) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipReal(void* p, \
bool aRemovingAllowed) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END \
(void)tmp; \
return false; \
}
// See documentation for nsCycleCollectionParticipant::CanSkipInCC for
// documentation about this method.
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_BEGIN(_class) \
NS_IMETHODIMP_(bool) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipInCCReal(void* p) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END \
(void)tmp; \
return false; \
}
// See documentation for nsCycleCollectionParticipant::CanSkipThis for
// documentation about this method.
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_BEGIN(_class) \
NS_IMETHODIMP_(bool) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipThisReal(void* p) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END \
(void)tmp; \
return false; \
}
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing nsCycleCollectionParticipant::Unlink
//
// You need to use NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED if you want
// the base class Unlink version to be called before your own implementation.
// You can use NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED if you want the
// base class Unlink to get called after your own implementation. You should
// never use them together.
///////////////////////////////////////////////////////////////////////////////
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
NS_IMETHODIMP_(void) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(void* p) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
nsISupports* s = static_cast<nsISupports*>(p); \
NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER(_field) \
ImplCycleCollectionUnlink(tmp->_field);
#define NS_IMPL_CYCLE_COLLECTION_UNLINK(...) \
MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER, (), (__VA_ARGS__))
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
(void)tmp; \
}
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(_base_class) \
nsISupports* s = static_cast<nsISupports*>(p); \
NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s); \
(void)tmp; \
}
#define NS_IMPL_CYCLE_COLLECTION_UNLINK_0(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing nsCycleCollectionParticipant::Traverse
///////////////////////////////////////////////////////////////////////////////
#define NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, _refcnt) \
cb.DescribeRefCountedNode(_refcnt, #_class);
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class) \
NS_IMETHODIMP \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::TraverseNative( \
void* p, nsCycleCollectionTraversalCallback& cb) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class) \
NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, tmp->mRefCnt.get())
// Base class' CC participant should return NS_SUCCESS_INTERRUPTED_TRAVERSE
// from Traverse if it wants derived classes to not traverse anything from
// their CC participant.
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base_class) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class) \
nsISupports* s = static_cast<nsISupports*>(p); \
if (NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::TraverseNative(s, cb) == \
NS_SUCCESS_INTERRUPTED_TRAVERSE) { \
return NS_SUCCESS_INTERRUPTED_TRAVERSE; \
}
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER(_field) \
ImplCycleCollectionTraverse(cb, tmp->_field, #_field, 0);
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE(...) \
MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER, (), (__VA_ARGS__))
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_RAWPTR(_field) \
CycleCollectionNoteChild(cb, tmp->_field, #_field);
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END \
(void)tmp; \
return NS_OK; \
}
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing nsScriptObjectTracer::Trace
///////////////////////////////////////////////////////////////////////////////
#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class) \
void NS_CYCLE_COLLECTION_CLASSNAME(_class)::Trace( \
void* p, const TraceCallbacks& aCallbacks, void* aClosure) { \
_class* tmp = DowncastCCParticipant<_class>(p);
#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(_class, _base_class) \
NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class) \
nsISupports* s = static_cast<nsISupports*>(p); \
NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Trace(s, aCallbacks, aClosure);
#define NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(_field) \
aCallbacks.Trace(&tmp->_field, #_field, aClosure);
// NB: The (void)tmp; hack in the TRACE_END macro exists to support
// implementations that don't need to do anything in their Trace method.
// Without this hack, some compilers warn about the unused tmp local.
#define NS_IMPL_CYCLE_COLLECTION_TRACE_END \
(void)tmp; \
}
///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing a concrete nsCycleCollectionParticipant
///////////////////////////////////////////////////////////////////////////////
// If a class defines a participant, then QIing an instance of that class to
// nsXPCOMCycleCollectionParticipant should produce that participant.
#ifdef DEBUG
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE \
virtual void CheckForRightParticipant()
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED \
virtual void CheckForRightParticipant() override
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class) \
{ \
nsXPCOMCycleCollectionParticipant* p; \
CallQueryInterface(this, &p); \
MOZ_ASSERT(p == &NS_CYCLE_COLLECTION_INNERNAME, \
#_class " should QI to its own CC participant"); \
}
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class) \
NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE \
NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class) \
NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED \
NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
#else
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)
# define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)
#endif
#define NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
NS_IMETHOD_(const char*) ClassName() override { return #_class; };
#define NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base) \
public: \
NS_IMETHOD TraverseNative(void* p, nsCycleCollectionTraversalCallback& cb) \
override; \
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
NS_IMETHOD_(void) DeleteCycleCollectable(void* p) override { \
DowncastCCParticipant<_class>(p)->DeleteCycleCollectable(); \
} \
static _class* Downcast(nsISupports* s) { \
return static_cast<_class*>(static_cast<_base*>(s)); \
} \
static nsISupports* Upcast(_class* p) { \
return NS_ISUPPORTS_CAST(_base*, p); \
} \
template <typename T> \
friend nsISupports* ToSupports(T* p, NS_CYCLE_COLLECTION_INNERCLASS* dummy); \
NS_IMETHOD_(void) Unlink(void* p) override;
#define NS_PARTICIPANT_AS(type, participant) \
const_cast<type*>(reinterpret_cast<const type*>(participant))
#define NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
static constexpr nsXPCOMCycleCollectionParticipant* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
}
/**
* We use this macro to force that classes that inherit from a ccable class and
* declare their own participant declare themselves as inherited cc classes.
* To avoid possibly unnecessary vtables we only do this checking in debug
* builds.
*/
#ifdef DEBUG
// clang-format off
// Force this line to remain this way to make sure we don't trigger the
// lint cpp-virtual-final. see bug 1505943
#define NOT_INHERITED_CANT_OVERRIDE virtual void BaseCycleCollectable() final {}
// clang-format on
#else
# define NOT_INHERITED_CANT_OVERRIDE
#endif
#define NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _base) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public nsXPCOMCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: nsXPCOMCycleCollectionParticipant(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base) \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
NOT_INHERITED_CANT_OVERRIDE
#define NS_DECL_CYCLE_COLLECTION_CLASS(_class) \
NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _class)
// Cycle collector helper for ambiguous classes that can sometimes be skipped.
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _base) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public nsXPCOMCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS( \
Flags aFlags = FlagMightSkip) /* We always want skippability. */ \
: nsXPCOMCycleCollectionParticipant(aFlags | FlagMightSkip) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base) \
NS_IMETHOD_(bool) CanSkipReal(void* p, bool aRemovingAllowed) override; \
NS_IMETHOD_(bool) CanSkipInCCReal(void* p) override; \
NS_IMETHOD_(bool) CanSkipThisReal(void* p) override; \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
NOT_INHERITED_CANT_OVERRIDE
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(_class) \
NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _class)
#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _base) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public nsXPCOMCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: nsXPCOMCycleCollectionParticipant(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base) \
NS_IMETHOD_(void) \
Trace(void* p, const TraceCallbacks& cb, void* closure) override; \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
NOT_INHERITED_CANT_OVERRIDE
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS( \
_class, _base) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public nsXPCOMCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS( \
Flags aFlags = FlagMightSkip) /* We always want skippability. */ \
: nsXPCOMCycleCollectionParticipant(aFlags | FlagMightSkip) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base) \
NS_IMETHOD_(void) \
Trace(void* p, const TraceCallbacks& cb, void* closure) override; \
NS_IMETHOD_(bool) CanSkipReal(void* p, bool aRemovingAllowed) override; \
NS_IMETHOD_(bool) CanSkipInCCReal(void* p) override; \
NS_IMETHOD_(bool) CanSkipThisReal(void* p) override; \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
NOT_INHERITED_CANT_OVERRIDE
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS(_class) \
NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, \
_class)
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_INHERITED( \
_class, _base_class) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public NS_CYCLE_COLLECTION_CLASSNAME(_base_class) { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS( \
Flags aFlags = FlagMightSkip) /* We always want skippability. */ \
: NS_CYCLE_COLLECTION_CLASSNAME(_base_class)(aFlags | FlagMightSkip) { \
} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class) \
NS_IMETHOD_(void) \
Trace(void* p, const TraceCallbacks& cb, void* closure) override; \
NS_IMETHOD_(bool) CanSkipReal(void* p, bool aRemovingAllowed) override; \
NS_IMETHOD_(bool) CanSkipInCCReal(void* p) override; \
NS_IMETHOD_(bool) CanSkipThisReal(void* p) override; \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(_class) \
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _class)
#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class) \
public: \
NS_IMETHOD TraverseNative(void* p, nsCycleCollectionTraversalCallback& cb) \
override; \
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
static _class* Downcast(nsISupports* s) { \
return static_cast<_class*>(static_cast<_base_class*>( \
NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Downcast(s))); \
} \
NS_IMETHOD_(void) Unlink(void* p) override;
#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(_class, _base_class) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public NS_CYCLE_COLLECTION_CLASSNAME(_base_class) { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: NS_CYCLE_COLLECTION_CLASSNAME(_base_class)(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class) \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(_class, \
_base_class) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public NS_CYCLE_COLLECTION_CLASSNAME(_base_class) { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: NS_CYCLE_COLLECTION_CLASSNAME(_base_class)(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class) \
NS_IMETHOD_(void) \
Trace(void* p, const TraceCallbacks& cb, void* closure) override; \
NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class) \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class) \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
// Cycle collector participant declarations.
#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class) \
public: \
NS_IMETHOD_(void) Root(void* n) override; \
NS_IMETHOD_(void) Unlink(void* n) override; \
NS_IMETHOD_(void) Unroot(void* n) override; \
NS_IMETHOD TraverseNative(void* n, nsCycleCollectionTraversalCallback& cb) \
override; \
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
NS_IMETHOD_(void) DeleteCycleCollectable(void* n) override { \
DowncastCCParticipant<_class>(n)->DeleteCycleCollectable(); \
} \
static _class* Downcast(void* s) { \
return DowncastCCParticipant<_class>(s); \
} \
static void* Upcast(_class* p) { return static_cast<void*>(p); }
#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(_class) \
void DeleteCycleCollectable(void) { delete this; } \
class NS_CYCLE_COLLECTION_INNERCLASS : public nsCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: nsCycleCollectionParticipant(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class) \
static constexpr nsCycleCollectionParticipant* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
} \
}; \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS(_class) \
void DeleteCycleCollectable(void) { delete this; } \
class NS_CYCLE_COLLECTION_INNERCLASS : public nsCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS( \
Flags aFlags = FlagMightSkip) /* We always want skippability. */ \
: nsCycleCollectionParticipant(aFlags | FlagMightSkip) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class) \
NS_IMETHOD_(bool) CanSkipReal(void* p, bool aRemovingAllowed) override; \
NS_IMETHOD_(bool) CanSkipInCCReal(void* p) override; \
NS_IMETHOD_(bool) CanSkipThisReal(void* p) override; \
static nsCycleCollectionParticipant* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
} \
}; \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS_WITH_CUSTOM_DELETE( \
_class) \
class NS_CYCLE_COLLECTION_INNERCLASS : public nsCycleCollectionParticipant { \
public: \
constexpr NS_CYCLE_COLLECTION_INNERCLASS() \
: nsCycleCollectionParticipant(true) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class) \
NS_IMETHOD_(bool) CanSkipReal(void* p, bool aRemovingAllowed) override; \
NS_IMETHOD_(bool) CanSkipInCCReal(void* p) override; \
NS_IMETHOD_(bool) CanSkipThisReal(void* p) override; \
static nsCycleCollectionParticipant* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
} \
}; \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(_class) \
void DeleteCycleCollectable(void) { delete this; } \
class NS_CYCLE_COLLECTION_INNERCLASS : public nsScriptObjectTracer { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(Flags aFlags = 0) \
: nsScriptObjectTracer(aFlags) {} \
\
private: \
NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class) \
NS_IMETHOD_(void) \
Trace(void* p, const TraceCallbacks& cb, void* closure) override; \
static constexpr nsScriptObjectTracer* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
} \
}; \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
#define NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(_class, _root_function) \
NS_IMETHODIMP_(void) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::Root(void* p) { \
_class* tmp = static_cast<_class*>(p); \
tmp->_root_function(); \
}
#define NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(_class, _unroot_function) \
NS_IMETHODIMP_(void) \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unroot(void* p) { \
_class* tmp = static_cast<_class*>(p); \
tmp->_unroot_function(); \
}
#define NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
_class::NS_CYCLE_COLLECTION_INNERCLASS _class::NS_CYCLE_COLLECTION_INNERNAME;
// Most JS holder classes should only contain pointers to JS GC things in a
// single JS zone, but there are some exceptions. Such classes should use this
// macro to tell the system about this.
#define NS_IMPL_CYCLE_COLLECTION_MULTI_ZONE_JSHOLDER_CLASS(_class) \
_class::NS_CYCLE_COLLECTION_INNERCLASS \
_class::NS_CYCLE_COLLECTION_INNERNAME( \
nsCycleCollectionParticipant::FlagMultiZoneJSHolder);
// NB: This is not something you usually want to use. It is here to allow
// adding things to the CC graph to help debugging via CC logs, but it does not
// traverse or unlink anything, so it is useless for anything else.
#define NS_IMPL_CYCLE_COLLECTION_0(_class) \
NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
#define NS_IMPL_CYCLE_COLLECTION(_class, ...) \
NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
// If you are looking for NS_IMPL_CYCLE_COLLECTION_INHERITED_0(_class, _base)
// you should instead not declare any cycle collected stuff in _class, so it
// will just inherit the CC declarations from _base.
#define NS_IMPL_CYCLE_COLLECTION_INHERITED(_class, _base, ...) \
NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base) \
NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__) \
NS_IMPL_CYCLE_COLLECTION_UNLINK_END \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__) \
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
#define NS_CYCLE_COLLECTION_NOTE_EDGE_NAME CycleCollectionNoteEdgeName
/**
* Convenience macros for defining nISupports methods in a cycle collected
* class.
*/
#define NS_IMPL_QUERY_INTERFACE_CYCLE_COLLECTION_INHERITED(aClass, aSuper, \
...) \
NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION_INHERITED(aClass) \
NS_INTERFACE_TABLE_INHERITED(aClass, __VA_ARGS__) \
NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)
#define NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(aClass, aSuper, ...) \
NS_IMPL_QUERY_INTERFACE_CYCLE_COLLECTION_INHERITED(aClass, aSuper, \
__VA_ARGS__) \
NS_IMPL_ADDREF_INHERITED(aClass, aSuper) \
NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
#define NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(aClass, aSuper) \
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(aClass) \
NS_INTERFACE_MAP_END_INHERITING(aSuper) \
NS_IMPL_ADDREF_INHERITED(aClass, aSuper) \
NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
/**
* Equivalency of the high three words where two IIDs have the same
* top three words but not the same low word.
*/
inline bool TopThreeWordsEquals(const nsID& aID, const nsID& aOther1,
const nsID& aOther2) {
MOZ_ASSERT((((uint32_t*)&aOther1.m0)[0] == ((uint32_t*)&aOther2.m0)[0]) &&
(((uint32_t*)&aOther1.m0)[1] == ((uint32_t*)&aOther2.m0)[1]) &&
(((uint32_t*)&aOther1.m0)[2] == ((uint32_t*)&aOther2.m0)[2]) &&
(((uint32_t*)&aOther1.m0)[3] != ((uint32_t*)&aOther2.m0)[3]));
return ((((uint32_t*)&aID.m0)[0] == ((uint32_t*)&aOther1.m0)[0]) &&
(((uint32_t*)&aID.m0)[1] == ((uint32_t*)&aOther1.m0)[1]) &&
(((uint32_t*)&aID.m0)[2] == ((uint32_t*)&aOther1.m0)[2]));
}
/**
* Equivalency of the fourth word where the two IIDs have the same
* top three words but not the same low word.
*/
inline bool LowWordEquals(const nsID& aID, const nsID& aOther) {
return (((uint32_t*)&aID.m0)[3] == ((uint32_t*)&aOther.m0)[3]);
}
#endif // nsCycleCollectionParticipant_h__