nsISupportsImpl.h
/* -*- 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/. */
// IWYU pragma: private, include "nsISupports.h"
#ifndef nsISupportsImpl_h__
#define nsISupportsImpl_h__
#include "nscore.h"
#include "nsISupportsBase.h"
#include "nsISupportsUtils.h"
#if !defined(XPCOM_GLUE_AVOID_NSPR)
#include "prthread.h" /* needed for thread-safety checks */
#endif // !XPCOM_GLUE_AVOID_NSPR
#include "nsDebug.h"
#include "nsXPCOM.h"
#ifndef XPCOM_GLUE
#include "mozilla/Atomics.h"
#endif
#include "mozilla/Attributes.h"
#include "mozilla/Assertions.h"
#include "mozilla/Compiler.h"
#include "mozilla/Likely.h"
#include "mozilla/MacroArgs.h"
#include "mozilla/MacroForEach.h"
#include "mozilla/TypeTraits.h"
#if defined(__clang__)
// bug 1028428 shows that at least in FreeBSD 10.0 with Clang 3.4 and libc++ 3.4,
// std::is_destructible is buggy in that it returns false when it should return true
// on ipc::SharedMemory. On the other hand, all Clang versions currently in use
// seem to handle the fallback just fine.
# define MOZ_CAN_USE_IS_DESTRUCTIBLE_FALLBACK
#elif defined(__GNUC__)
// GCC 4.7 is has buggy std::is_destructible
# if MOZ_USING_LIBSTDCXX && MOZ_GCC_VERSION_AT_LEAST(4, 8, 0)
# define MOZ_HAVE_STD_IS_DESTRUCTIBLE
// Some GCC versions have an ICE when using destructors in decltype().
// Works on GCC 4.8 at least.
# elif MOZ_GCC_VERSION_AT_LEAST(4, 8, 0)
# define MOZ_CAN_USE_IS_DESTRUCTIBLE_FALLBACK
# endif
#endif
#ifdef MOZ_HAVE_STD_IS_DESTRUCTIBLE
# include <type_traits>
# define MOZ_IS_DESTRUCTIBLE(X) (std::is_destructible<X>::value)
#elif defined MOZ_CAN_USE_IS_DESTRUCTIBLE_FALLBACK
namespace mozilla {
struct IsDestructibleFallbackImpl
{
template<typename T, typename = decltype(DeclVal<T>().~T())>
static TrueType Test(int);
template<typename>
static FalseType Test(...);
template<typename T>
struct Selector
{
typedef decltype(Test<T>(0)) type;
};
};
template<typename T>
struct IsDestructibleFallback
: IsDestructibleFallbackImpl::Selector<T>::type
{
};
} // namespace mozilla
# define MOZ_IS_DESTRUCTIBLE(X) (mozilla::IsDestructibleFallback<X>::value)
#endif
#ifdef MOZ_IS_DESTRUCTIBLE
#define MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(X) \
static_assert(!MOZ_IS_DESTRUCTIBLE(X), \
"Reference-counted class " #X " should not have a public destructor. " \
"Make this class's destructor non-public");
#else
#define MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(X)
#endif
inline nsISupports*
ToSupports(nsISupports* aSupports)
{
return aSupports;
}
inline nsISupports*
ToCanonicalSupports(nsISupports* aSupports)
{
return nullptr;
}
////////////////////////////////////////////////////////////////////////////////
// Macros to help detect thread-safety:
#if (defined(DEBUG) || (defined(NIGHTLY_BUILD) && !defined(MOZ_PROFILING))) && !defined(XPCOM_GLUE_AVOID_NSPR)
class nsAutoOwningThread
{
public:
nsAutoOwningThread() { mThread = PR_GetCurrentThread(); }
void* GetThread() const { return mThread; }
private:
void* mThread;
};
#define NS_DECL_OWNINGTHREAD nsAutoOwningThread _mOwningThread;
#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) \
NS_CheckThreadSafe(agg->_mOwningThread.GetThread(), #_class " not thread-safe")
#define NS_ASSERT_OWNINGTHREAD(_class) NS_ASSERT_OWNINGTHREAD_AGGREGATE(this, _class)
#else // !DEBUG && !(NIGHTLY_BUILD && !MOZ_PROFILING)
#define NS_DECL_OWNINGTHREAD /* nothing */
#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) ((void)0)
#define NS_ASSERT_OWNINGTHREAD(_class) ((void)0)
#endif // DEBUG || (NIGHTLY_BUILD && !MOZ_PROFILING)
// Macros for reference-count and constructor logging
#if defined(NS_BUILD_REFCNT_LOGGING)
#define NS_LOG_ADDREF(_p, _rc, _type, _size) \
NS_LogAddRef((_p), (_rc), (_type), (uint32_t) (_size))
#define NS_LOG_RELEASE(_p, _rc, _type) \
NS_LogRelease((_p), (_rc), (_type))
#include "mozilla/TypeTraits.h"
#define MOZ_ASSERT_CLASSNAME(_type) \
static_assert(mozilla::IsClass<_type>::value, \
"Token '" #_type "' is not a class type.")
// Older versions of gcc can't instantiate local classes in templates.
// GCC 4.7 doesn't have this problem.
#if MOZ_IS_GCC
# if !MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
# undef MOZ_ASSERT_CLASSNAME
# define MOZ_ASSERT_CLASSNAME(_type)
# endif
#endif
// Note that the following constructor/destructor logging macros are redundant
// for refcounted objects that log via the NS_LOG_ADDREF/NS_LOG_RELEASE macros.
// Refcount logging is preferred.
#define MOZ_COUNT_CTOR(_type) \
do { \
MOZ_ASSERT_CLASSNAME(_type); \
NS_LogCtor((void*)this, #_type, sizeof(*this)); \
} while (0)
#define MOZ_COUNT_CTOR_INHERITED(_type, _base) \
do { \
MOZ_ASSERT_CLASSNAME(_type); \
MOZ_ASSERT_CLASSNAME(_base); \
NS_LogCtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
} while (0)
#define MOZ_LOG_CTOR(_ptr, _name, _size) \
do { \
NS_LogCtor((void*)_ptr, _name, _size); \
} while (0)
#define MOZ_COUNT_DTOR(_type) \
do { \
MOZ_ASSERT_CLASSNAME(_type); \
NS_LogDtor((void*)this, #_type, sizeof(*this)); \
} while (0)
#define MOZ_COUNT_DTOR_INHERITED(_type, _base) \
do { \
MOZ_ASSERT_CLASSNAME(_type); \
MOZ_ASSERT_CLASSNAME(_base); \
NS_LogDtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
} while (0)
#define MOZ_LOG_DTOR(_ptr, _name, _size) \
do { \
NS_LogDtor((void*)_ptr, _name, _size); \
} while (0)
/* nsCOMPtr.h allows these macros to be defined by clients
* These logging functions require dynamic_cast<void*>, so they don't
* do anything useful if we don't have dynamic_cast<void*>. */
#define NSCAP_LOG_ASSIGNMENT(_c, _p) \
if (_p) \
NS_LogCOMPtrAddRef((_c),static_cast<nsISupports*>(_p))
#define NSCAP_LOG_RELEASE(_c, _p) \
if (_p) \
NS_LogCOMPtrRelease((_c), static_cast<nsISupports*>(_p))
#else /* !NS_BUILD_REFCNT_LOGGING */
#define NS_LOG_ADDREF(_p, _rc, _type, _size)
#define NS_LOG_RELEASE(_p, _rc, _type)
#define MOZ_COUNT_CTOR(_type)
#define MOZ_COUNT_CTOR_INHERITED(_type, _base)
#define MOZ_LOG_CTOR(_ptr, _name, _size)
#define MOZ_COUNT_DTOR(_type)
#define MOZ_COUNT_DTOR_INHERITED(_type, _base)
#define MOZ_LOG_DTOR(_ptr, _name, _size)
#endif /* NS_BUILD_REFCNT_LOGGING */
// Support for ISupports classes which interact with cycle collector.
#define NS_NUMBER_OF_FLAGS_IN_REFCNT 2
#define NS_IN_PURPLE_BUFFER (1 << 0)
#define NS_IS_PURPLE (1 << 1)
#define NS_REFCOUNT_CHANGE (1 << NS_NUMBER_OF_FLAGS_IN_REFCNT)
#define NS_REFCOUNT_VALUE(_val) (_val >> NS_NUMBER_OF_FLAGS_IN_REFCNT)
class nsCycleCollectingAutoRefCnt
{
public:
nsCycleCollectingAutoRefCnt() : mRefCntAndFlags(0) {}
explicit nsCycleCollectingAutoRefCnt(uintptr_t aValue)
: mRefCntAndFlags(aValue << NS_NUMBER_OF_FLAGS_IN_REFCNT)
{
}
MOZ_ALWAYS_INLINE uintptr_t incr(nsISupports* aOwner)
{
return incr(aOwner, nullptr);
}
MOZ_ALWAYS_INLINE uintptr_t incr(void* aOwner,
nsCycleCollectionParticipant* aCp)
{
mRefCntAndFlags += NS_REFCOUNT_CHANGE;
mRefCntAndFlags &= ~NS_IS_PURPLE;
// For incremental cycle collection, use the purple buffer to track objects
// that have been AddRef'd.
if (!IsInPurpleBuffer()) {
mRefCntAndFlags |= NS_IN_PURPLE_BUFFER;
// Refcount isn't zero, so Suspect won't delete anything.
MOZ_ASSERT(get() > 0);
NS_CycleCollectorSuspect3(aOwner, aCp, this, nullptr);
}
return NS_REFCOUNT_VALUE(mRefCntAndFlags);
}
MOZ_ALWAYS_INLINE void stabilizeForDeletion()
{
// Set refcnt to 1 and mark us to be in the purple buffer.
// This way decr won't call suspect again.
mRefCntAndFlags = NS_REFCOUNT_CHANGE | NS_IN_PURPLE_BUFFER;
}
MOZ_ALWAYS_INLINE uintptr_t decr(nsISupports* aOwner,
bool* aShouldDelete = nullptr)
{
return decr(aOwner, nullptr, aShouldDelete);
}
MOZ_ALWAYS_INLINE uintptr_t decr(void* aOwner,
nsCycleCollectionParticipant* aCp,
bool* aShouldDelete = nullptr)
{
MOZ_ASSERT(get() > 0);
if (!IsInPurpleBuffer()) {
mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
uintptr_t retval = NS_REFCOUNT_VALUE(mRefCntAndFlags);
// Suspect may delete 'aOwner' and 'this'!
NS_CycleCollectorSuspect3(aOwner, aCp, this, aShouldDelete);
return retval;
}
mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
return NS_REFCOUNT_VALUE(mRefCntAndFlags);
}
MOZ_ALWAYS_INLINE void RemovePurple()
{
MOZ_ASSERT(IsPurple(), "must be purple");
mRefCntAndFlags &= ~NS_IS_PURPLE;
}
MOZ_ALWAYS_INLINE void RemoveFromPurpleBuffer()
{
MOZ_ASSERT(IsInPurpleBuffer());
mRefCntAndFlags &= ~(NS_IS_PURPLE | NS_IN_PURPLE_BUFFER);
}
MOZ_ALWAYS_INLINE bool IsPurple() const
{
return !!(mRefCntAndFlags & NS_IS_PURPLE);
}
MOZ_ALWAYS_INLINE bool IsInPurpleBuffer() const
{
return !!(mRefCntAndFlags & NS_IN_PURPLE_BUFFER);
}
MOZ_ALWAYS_INLINE nsrefcnt get() const
{
return NS_REFCOUNT_VALUE(mRefCntAndFlags);
}
MOZ_ALWAYS_INLINE operator nsrefcnt() const
{
return get();
}
private:
uintptr_t mRefCntAndFlags;
};
class nsAutoRefCnt
{
public:
nsAutoRefCnt() : mValue(0) {}
explicit nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
// only support prefix increment/decrement
nsrefcnt operator++() { return ++mValue; }
nsrefcnt operator--() { return --mValue; }
nsrefcnt operator=(nsrefcnt aValue) { return (mValue = aValue); }
operator nsrefcnt() const { return mValue; }
nsrefcnt get() const { return mValue; }
static const bool isThreadSafe = false;
private:
nsrefcnt operator++(int) = delete;
nsrefcnt operator--(int) = delete;
nsrefcnt mValue;
};
#ifndef XPCOM_GLUE
namespace mozilla {
class ThreadSafeAutoRefCnt
{
public:
ThreadSafeAutoRefCnt() : mValue(0) {}
explicit ThreadSafeAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
// only support prefix increment/decrement
MOZ_ALWAYS_INLINE nsrefcnt operator++() { return ++mValue; }
MOZ_ALWAYS_INLINE nsrefcnt operator--() { return --mValue; }
MOZ_ALWAYS_INLINE nsrefcnt operator=(nsrefcnt aValue)
{
return (mValue = aValue);
}
MOZ_ALWAYS_INLINE operator nsrefcnt() const { return mValue; }
MOZ_ALWAYS_INLINE nsrefcnt get() const { return mValue; }
static const bool isThreadSafe = true;
private:
nsrefcnt operator++(int) = delete;
nsrefcnt operator--(int) = delete;
// In theory, RelaseAcquire consistency (but no weaker) is sufficient for
// the counter. Making it weaker could speed up builds on ARM (but not x86),
// but could break pre-existing code that assumes sequential consistency.
Atomic<nsrefcnt> mValue;
};
} // namespace mozilla
#endif
///////////////////////////////////////////////////////////////////////////////
/**
* Declare the reference count variable and the implementations of the
* AddRef and QueryInterface methods.
*/
#define NS_DECL_ISUPPORTS \
public: \
NS_IMETHOD QueryInterface(REFNSIID aIID, \
void** aInstancePtr) override; \
NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; \
NS_IMETHOD_(MozExternalRefCountType) Release(void) override; \
protected: \
nsAutoRefCnt mRefCnt; \
NS_DECL_OWNINGTHREAD \
public:
#define NS_DECL_THREADSAFE_ISUPPORTS \
public: \
NS_IMETHOD QueryInterface(REFNSIID aIID, \
void** aInstancePtr) override; \
NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; \
NS_IMETHOD_(MozExternalRefCountType) Release(void) override; \
protected: \
::mozilla::ThreadSafeAutoRefCnt mRefCnt; \
NS_DECL_OWNINGTHREAD \
public:
#define NS_DECL_CYCLE_COLLECTING_ISUPPORTS \
public: \
NS_IMETHOD QueryInterface(REFNSIID aIID, \
void** aInstancePtr) override; \
NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; \
NS_IMETHOD_(MozExternalRefCountType) Release(void) override; \
NS_IMETHOD_(void) DeleteCycleCollectable(void); \
protected: \
nsCycleCollectingAutoRefCnt mRefCnt; \
NS_DECL_OWNINGTHREAD \
public:
///////////////////////////////////////////////////////////////////////////////
/*
* Implementation of AddRef and Release for non-nsISupports (ie "native")
* cycle-collected classes that use the purple buffer to avoid leaks.
*/
#define NS_IMPL_CC_NATIVE_ADDREF_BODY(_class) \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt"); \
NS_ASSERT_OWNINGTHREAD(_class); \
nsrefcnt count = \
mRefCnt.incr(static_cast<void*>(this), \
_class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
NS_LOG_ADDREF(this, count, #_class, sizeof(*this)); \
return count;
#define NS_IMPL_CC_NATIVE_RELEASE_BODY(_class) \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
nsrefcnt count = \
mRefCnt.decr(static_cast<void*>(this), \
_class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
NS_LOG_RELEASE(this, count, #_class); \
return count;
#define NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(_class) \
NS_METHOD_(MozExternalRefCountType) _class::AddRef(void) \
{ \
NS_IMPL_CC_NATIVE_ADDREF_BODY(_class) \
}
#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE_WITH_LAST_RELEASE(_class, _last) \
NS_METHOD_(MozExternalRefCountType) _class::Release(void) \
{ \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
bool shouldDelete = false; \
nsrefcnt count = \
mRefCnt.decr(static_cast<void*>(this), \
_class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant(), \
&shouldDelete); \
NS_LOG_RELEASE(this, count, #_class); \
if (count == 0) { \
mRefCnt.incr(static_cast<void*>(this), \
_class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
_last; \
mRefCnt.decr(static_cast<void*>(this), \
_class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
if (shouldDelete) { \
mRefCnt.stabilizeForDeletion(); \
DeleteCycleCollectable(); \
} \
} \
return count; \
}
#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE(_class) \
NS_METHOD_(MozExternalRefCountType) _class::Release(void) \
{ \
NS_IMPL_CC_NATIVE_RELEASE_BODY(_class) \
}
#define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(_class) \
public: \
NS_METHOD_(MozExternalRefCountType) AddRef(void) { \
NS_IMPL_CC_NATIVE_ADDREF_BODY(_class) \
} \
NS_METHOD_(MozExternalRefCountType) Release(void) { \
NS_IMPL_CC_NATIVE_RELEASE_BODY(_class) \
} \
protected: \
nsCycleCollectingAutoRefCnt mRefCnt; \
NS_DECL_OWNINGTHREAD \
public:
///////////////////////////////////////////////////////////////////////////////
/**
* Use this macro to declare and implement the AddRef & Release methods for a
* given non-XPCOM <i>_class</i>.
*
* @param _class The name of the class implementing the method
* @param optional override Mark the AddRef & Release methods as overrides.
*/
#define NS_INLINE_DECL_REFCOUNTING(_class, ...) \
public: \
NS_METHOD_(MozExternalRefCountType) AddRef(void) __VA_ARGS__ { \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt"); \
NS_ASSERT_OWNINGTHREAD(_class); \
++mRefCnt; \
NS_LOG_ADDREF(this, mRefCnt, #_class, sizeof(*this)); \
return mRefCnt; \
} \
NS_METHOD_(MozExternalRefCountType) Release(void) __VA_ARGS__ { \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
--mRefCnt; \
NS_LOG_RELEASE(this, mRefCnt, #_class); \
if (mRefCnt == 0) { \
NS_ASSERT_OWNINGTHREAD(_class); \
mRefCnt = 1; /* stabilize */ \
delete this; \
return 0; \
} \
return mRefCnt; \
} \
protected: \
nsAutoRefCnt mRefCnt; \
NS_DECL_OWNINGTHREAD \
public:
#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, _decl, ...) \
public: \
_decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__ { \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt"); \
nsrefcnt count = ++mRefCnt; \
NS_LOG_ADDREF(this, count, #_class, sizeof(*this)); \
return (nsrefcnt) count; \
} \
_decl(MozExternalRefCountType) Release(void) __VA_ARGS__ { \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
nsrefcnt count = --mRefCnt; \
NS_LOG_RELEASE(this, count, #_class); \
if (count == 0) { \
delete (this); \
return 0; \
} \
return count; \
} \
protected: \
::mozilla::ThreadSafeAutoRefCnt mRefCnt; \
public:
/**
* Use this macro to declare and implement the AddRef & Release methods for a
* given non-XPCOM <i>_class</i> in a threadsafe manner.
*
* DOES NOT DO REFCOUNT STABILIZATION!
*
* @param _class The name of the class implementing the method
*/
#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING(_class, ...) \
NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_METHOD_, __VA_ARGS__)
/**
* Like NS_INLINE_DECL_THREADSAFE_REFCOUNTING with AddRef & Release declared
* virtual.
*/
#define NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING(_class, ...) \
NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_IMETHOD_, __VA_ARGS__)
/**
* Use this macro to implement the AddRef method for a given <i>_class</i>
* @param _class The name of the class implementing the method
*/
#define NS_IMPL_ADDREF(_class) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) \
{ \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt"); \
if (!mRefCnt.isThreadSafe) \
NS_ASSERT_OWNINGTHREAD(_class); \
nsrefcnt count = ++mRefCnt; \
NS_LOG_ADDREF(this, count, #_class, sizeof(*this)); \
return count; \
}
/**
* Use this macro to implement the AddRef method for a given <i>_class</i>
* implemented as a wholly owned aggregated object intended to implement
* interface(s) for its owner
* @param _class The name of the class implementing the method
* @param _aggregator the owning/containing object
*/
#define NS_IMPL_ADDREF_USING_AGGREGATOR(_class, _aggregator) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) \
{ \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
NS_PRECONDITION(_aggregator, "null aggregator"); \
return (_aggregator)->AddRef(); \
}
/**
* Use this macro to implement the Release method for a given
* <i>_class</i>.
* @param _class The name of the class implementing the method
* @param _destroy A statement that is executed when the object's
* refcount drops to zero.
*
* For example,
*
* NS_IMPL_RELEASE_WITH_DESTROY(Foo, Destroy(this))
*
* will cause
*
* Destroy(this);
*
* to be invoked when the object's refcount drops to zero. This
* allows for arbitrary teardown activity to occur (e.g., deallocation
* of object allocated with placement new).
*/
#define NS_IMPL_RELEASE_WITH_DESTROY(_class, _destroy) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) \
{ \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
if (!mRefCnt.isThreadSafe) \
NS_ASSERT_OWNINGTHREAD(_class); \
nsrefcnt count = --mRefCnt; \
NS_LOG_RELEASE(this, count, #_class); \
if (count == 0) { \
if (!mRefCnt.isThreadSafe) \
NS_ASSERT_OWNINGTHREAD(_class); \
mRefCnt = 1; /* stabilize */ \
_destroy; \
return 0; \
} \
return count; \
}
/**
* Use this macro to implement the Release method for a given <i>_class</i>
* @param _class The name of the class implementing the method
*
* A note on the 'stabilization' of the refcnt to one. At that point,
* the object's refcount will have gone to zero. The object's
* destructor may trigger code that attempts to QueryInterface() and
* Release() 'this' again. Doing so will temporarily increment and
* decrement the refcount. (Only a logic error would make one try to
* keep a permanent hold on 'this'.) To prevent re-entering the
* destructor, we make sure that no balanced refcounting can return
* the refcount to |0|.
*/
#define NS_IMPL_RELEASE(_class) \
NS_IMPL_RELEASE_WITH_DESTROY(_class, delete (this))
/**
* Use this macro to implement the Release method for a given <i>_class</i>
* implemented as a wholly owned aggregated object intended to implement
* interface(s) for its owner
* @param _class The name of the class implementing the method
* @param _aggregator the owning/containing object
*/
#define NS_IMPL_RELEASE_USING_AGGREGATOR(_class, _aggregator) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) \
{ \
NS_PRECONDITION(_aggregator, "null aggregator"); \
return (_aggregator)->Release(); \
}
#define NS_IMPL_CYCLE_COLLECTING_ADDREF(_class) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) \
{ \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class) \
MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt"); \
NS_ASSERT_OWNINGTHREAD(_class); \
nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
nsrefcnt count = mRefCnt.incr(base); \
NS_LOG_ADDREF(this, count, #_class, sizeof(*this)); \
return count; \
}
#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, _destroy) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) \
{ \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
nsrefcnt count = mRefCnt.decr(base); \
NS_LOG_RELEASE(this, count, #_class); \
return count; \
} \
NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) \
{ \
_destroy; \
}
#define NS_IMPL_CYCLE_COLLECTING_RELEASE(_class) \
NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, delete (this))
// _LAST_RELEASE can be useful when certain resources should be released
// as soon as we know the object will be deleted.
#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(_class, _last) \
NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) \
{ \
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
bool shouldDelete = false; \
nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
nsrefcnt count = mRefCnt.decr(base, &shouldDelete); \
NS_LOG_RELEASE(this, count, #_class); \
if (count == 0) { \
mRefCnt.incr(base); \
_last; \
mRefCnt.decr(base); \
if (shouldDelete) { \
mRefCnt.stabilizeForDeletion(); \
DeleteCycleCollectable(); \
} \
} \
return count; \
} \
NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) \
{ \
delete this; \
}
///////////////////////////////////////////////////////////////////////////////
/**
* There are two ways of implementing QueryInterface, and we use both:
*
* Table-driven QueryInterface uses a static table of IID->offset mappings
* and a shared helper function. Using it tends to reduce codesize and improve
* runtime performance (due to processor cache hits).
*
* Macro-driven QueryInterface generates a QueryInterface function directly
* using common macros. This is necessary if special QueryInterface features
* are being used (such as tearoffs and conditional interfaces).
*
* These methods can be combined into a table-driven function call followed
* by custom code for tearoffs and conditionals.
*/
struct QITableEntry
{
const nsIID* iid; // null indicates end of the QITableEntry array
int32_t offset;
};
nsresult NS_FASTCALL
NS_TableDrivenQI(void* aThis, REFNSIID aIID,
void** aInstancePtr, const QITableEntry* aEntries);
/**
* Implement table-driven queryinterface
*/
#define NS_INTERFACE_TABLE_HEAD(_class) \
NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr) \
{ \
NS_ASSERTION(aInstancePtr, \
"QueryInterface requires a non-NULL destination!"); \
nsresult rv = NS_ERROR_FAILURE;
#define NS_INTERFACE_TABLE_BEGIN \
static const QITableEntry table[] = {
#define NS_INTERFACE_TABLE_ENTRY(_class, _interface) \
{ &NS_GET_IID(_interface), \
int32_t(reinterpret_cast<char*>( \
static_cast<_interface*>((_class*) 0x1000)) - \
reinterpret_cast<char*>((_class*) 0x1000)) \
},
#define NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(_class, _interface, _implClass) \
{ &NS_GET_IID(_interface), \
int32_t(reinterpret_cast<char*>( \
static_cast<_interface*>( \
static_cast<_implClass*>( \
(_class*) 0x1000))) - \
reinterpret_cast<char*>((_class*) 0x1000)) \
},
/*
* XXX: we want to use mozilla::ArrayLength (or equivalent,
* MOZ_ARRAY_LENGTH) in this condition, but some versions of GCC don't
* see that the static_assert condition is actually constant in those
* cases, even with constexpr support (?).
*/
#define NS_INTERFACE_TABLE_END_WITH_PTR(_ptr) \
{ nullptr, 0 } }; \
static_assert((sizeof(table)/sizeof(table[0])) > 1, "need at least 1 interface"); \
rv = NS_TableDrivenQI(static_cast<void*>(_ptr), \
aIID, aInstancePtr, table);
#define NS_INTERFACE_TABLE_END \
NS_INTERFACE_TABLE_END_WITH_PTR(this)
#define NS_INTERFACE_TABLE_TAIL \
return rv; \
}
#define NS_INTERFACE_TABLE_TAIL_INHERITING(_baseclass) \
if (NS_SUCCEEDED(rv)) \
return rv; \
return _baseclass::QueryInterface(aIID, aInstancePtr); \
}
#define NS_INTERFACE_TABLE_TAIL_USING_AGGREGATOR(_aggregator) \
if (NS_SUCCEEDED(rv)) \
return rv; \
NS_ASSERTION(_aggregator, "null aggregator"); \
return _aggregator->QueryInterface(aIID, aInstancePtr) \
}
/**
* This implements query interface with two assumptions: First, the
* class in question implements nsISupports and its own interface and
* nothing else. Second, the implementation of the class's primary
* inheritance chain leads to its own interface.
*
* @param _class The name of the class implementing the method
* @param _classiiddef The name of the #define symbol that defines the IID
* for the class (e.g. NS_ISUPPORTS_IID)
*/
#define NS_IMPL_QUERY_HEAD(_class) \
NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr) \
{ \
NS_ASSERTION(aInstancePtr, \
"QueryInterface requires a non-NULL destination!"); \
nsISupports* foundInterface;
#define NS_IMPL_QUERY_BODY(_interface) \
if ( aIID.Equals(NS_GET_IID(_interface)) ) \
foundInterface = static_cast<_interface*>(this); \
else
#define NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition) \
if ( (condition) && aIID.Equals(NS_GET_IID(_interface))) \
foundInterface = static_cast<_interface*>(this); \
else
#define NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass) \
if ( aIID.Equals(NS_GET_IID(_interface)) ) \
foundInterface = static_cast<_interface*>( \
static_cast<_implClass*>(this)); \
else
#define NS_IMPL_QUERY_BODY_AGGREGATED(_interface, _aggregate) \
if ( aIID.Equals(NS_GET_IID(_interface)) ) \
foundInterface = static_cast<_interface*>(_aggregate); \
else
#define NS_IMPL_QUERY_TAIL_GUTS \
foundInterface = 0; \
nsresult status; \
if ( !foundInterface ) \
{ \
/* nsISupports should be handled by this point. If not, fail. */ \
MOZ_ASSERT(!aIID.Equals(NS_GET_IID(nsISupports))); \
status = NS_NOINTERFACE; \
} \
else \
{ \
NS_ADDREF(foundInterface); \
status = NS_OK; \
} \
*aInstancePtr = foundInterface; \
return status; \
}
#define NS_IMPL_QUERY_TAIL_INHERITING(_baseclass) \
foundInterface = 0; \
nsresult status; \
if ( !foundInterface ) \
status = _baseclass::QueryInterface(aIID, (void**)&foundInterface); \
else \
{ \
NS_ADDREF(foundInterface); \
status = NS_OK; \
} \
*aInstancePtr = foundInterface; \
return status; \
}
#define NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator) \
foundInterface = 0; \
nsresult status; \
if ( !foundInterface ) { \
NS_ASSERTION(_aggregator, "null aggregator"); \
status = _aggregator->QueryInterface(aIID, (void**)&foundInterface); \
} else \
{ \
NS_ADDREF(foundInterface); \
status = NS_OK; \
} \
*aInstancePtr = foundInterface; \
return status; \
}
#define NS_IMPL_QUERY_TAIL(_supports_interface) \
NS_IMPL_QUERY_BODY_AMBIGUOUS(nsISupports, _supports_interface) \
NS_IMPL_QUERY_TAIL_GUTS
/*
This is the new scheme. Using this notation now will allow us to switch to
a table driven mechanism when it's ready. Note the difference between this
and the (currently) underlying NS_IMPL_QUERY_INTERFACE mechanism. You must
explicitly mention |nsISupports| when using the interface maps.
*/
#define NS_INTERFACE_MAP_BEGIN(_implClass) NS_IMPL_QUERY_HEAD(_implClass)
#define NS_INTERFACE_MAP_ENTRY(_interface) NS_IMPL_QUERY_BODY(_interface)
#define NS_INTERFACE_MAP_ENTRY_CONDITIONAL(_interface, condition) \
NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)
#define NS_INTERFACE_MAP_ENTRY_AGGREGATED(_interface,_aggregate) \
NS_IMPL_QUERY_BODY_AGGREGATED(_interface,_aggregate)
#define NS_INTERFACE_MAP_END NS_IMPL_QUERY_TAIL_GUTS
#define NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(_interface, _implClass) \
NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)
#define NS_INTERFACE_MAP_END_INHERITING(_baseClass) \
NS_IMPL_QUERY_TAIL_INHERITING(_baseClass)
#define NS_INTERFACE_MAP_END_AGGREGATED(_aggregator) \
NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)
#define NS_INTERFACE_TABLE0(_class) \
NS_INTERFACE_TABLE_BEGIN \
NS_INTERFACE_TABLE_ENTRY(_class, nsISupports) \
NS_INTERFACE_TABLE_END
#define NS_INTERFACE_TABLE(aClass, ...) \
MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__); \
NS_INTERFACE_TABLE_BEGIN \
MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__)) \
NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(aClass, nsISupports, \
MOZ_ARG_1(__VA_ARGS__)) \
NS_INTERFACE_TABLE_END
#define NS_IMPL_QUERY_INTERFACE0(_class) \
NS_INTERFACE_TABLE_HEAD(_class) \
NS_INTERFACE_TABLE0(_class) \
NS_INTERFACE_TABLE_TAIL
#define NS_IMPL_QUERY_INTERFACE(aClass, ...) \
NS_INTERFACE_TABLE_HEAD(aClass) \
NS_INTERFACE_TABLE(aClass, __VA_ARGS__) \
NS_INTERFACE_TABLE_TAIL
/**
* Declare that you're going to inherit from something that already
* implements nsISupports, but also implements an additional interface, thus
* causing an ambiguity. In this case you don't need another mRefCnt, you
* just need to forward the definitions to the appropriate superclass. E.g.
*
* class Bar : public Foo, public nsIBar { // both provide nsISupports
* public:
* NS_DECL_ISUPPORTS_INHERITED
* ...other nsIBar and Bar methods...
* };
*/
#define NS_DECL_ISUPPORTS_INHERITED \
public: \
NS_IMETHOD QueryInterface(REFNSIID aIID, \
void** aInstancePtr) override; \
NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; \
NS_IMETHOD_(MozExternalRefCountType) Release(void) override; \
/**
* These macros can be used in conjunction with NS_DECL_ISUPPORTS_INHERITED
* to implement the nsISupports methods, forwarding the invocations to a
* superclass that already implements nsISupports.
*
* Note that I didn't make these inlined because they're virtual methods.
*/
#define NS_IMPL_ADDREF_INHERITED(Class, Super) \
NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void) \
{ \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class) \
nsrefcnt r = Super::AddRef(); \
NS_LOG_ADDREF(this, r, #Class, sizeof(*this)); \
return r; \
}
#define NS_IMPL_RELEASE_INHERITED(Class, Super) \
NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void) \
{ \
nsrefcnt r = Super::Release(); \
NS_LOG_RELEASE(this, r, #Class); \
return r; \
}
/**
* As above but not logging the addref/release; needed if the base
* class might be aggregated.
*/
#define NS_IMPL_NONLOGGING_ADDREF_INHERITED(Class, Super) \
NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void) \
{ \
MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class) \
return Super::AddRef(); \
}
#define NS_IMPL_NONLOGGING_RELEASE_INHERITED(Class, Super) \
NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void) \
{ \
return Super::Release(); \
}
#define NS_INTERFACE_TABLE_INHERITED0(Class) /* Nothing to do here */
#define NS_INTERFACE_TABLE_INHERITED(aClass, ...) \
MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__); \
NS_INTERFACE_TABLE_BEGIN \
MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__)) \
NS_INTERFACE_TABLE_END
#define NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, ...) \
NS_INTERFACE_TABLE_HEAD(aClass) \
NS_INTERFACE_TABLE_INHERITED(aClass, __VA_ARGS__) \
NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)
/**
* Convenience macros for implementing all nsISupports methods for
* a simple class.
* @param _class The name of the class implementing the method
* @param _classiiddef The name of the #define symbol that defines the IID
* for the class (e.g. NS_ISUPPORTS_IID)
*/
#define NS_IMPL_ISUPPORTS0(_class) \
NS_IMPL_ADDREF(_class) \
NS_IMPL_RELEASE(_class) \
NS_IMPL_QUERY_INTERFACE0(_class)
#define NS_IMPL_ISUPPORTS(aClass, ...) \
NS_IMPL_ADDREF(aClass) \
NS_IMPL_RELEASE(aClass) \
NS_IMPL_QUERY_INTERFACE(aClass, __VA_ARGS__)
#define NS_IMPL_ISUPPORTS_INHERITED0(aClass, aSuper) \
NS_INTERFACE_TABLE_HEAD(aClass) \
NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper) \
NS_IMPL_ADDREF_INHERITED(aClass, aSuper) \
NS_IMPL_RELEASE_INHERITED(aClass, aSuper) \
#define NS_IMPL_ISUPPORTS_INHERITED(aClass, aSuper, ...) \
NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, __VA_ARGS__) \
NS_IMPL_ADDREF_INHERITED(aClass, aSuper) \
NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
/*
* Macro to glue together a QI that starts with an interface table
* and segues into an interface map (e.g. it uses singleton classinfo
* or tearoffs).
*/
#define NS_INTERFACE_TABLE_TO_MAP_SEGUE \
if (rv == NS_OK) return rv; \
nsISupports* foundInterface;
///////////////////////////////////////////////////////////////////////////////
/**
*
* Threadsafe implementations of the ISupports convenience macros.
*
* @note These are not available when linking against the standalone glue,
* because the implementation requires PR_ symbols.
*/
#define NS_INTERFACE_MAP_END_THREADSAFE NS_IMPL_QUERY_TAIL_GUTS
/**
* Macro to generate nsIClassInfo methods for classes which do not have
* corresponding nsIFactory implementations.
*/
#define NS_IMPL_THREADSAFE_CI(_class) \
NS_IMETHODIMP \
_class::GetInterfaces(uint32_t* _count, nsIID*** _array) \
{ \
return NS_CI_INTERFACE_GETTER_NAME(_class)(_count, _array); \
} \
\
NS_IMETHODIMP \
_class::GetScriptableHelper(nsIXPCScriptable** _retval) \
{ \
*_retval = nullptr; \
return NS_OK; \
} \
\
NS_IMETHODIMP \
_class::GetContractID(char** _contractID) \
{ \
*_contractID = nullptr; \
return NS_OK; \
} \
\
NS_IMETHODIMP \
_class::GetClassDescription(char** _classDescription) \
{ \
*_classDescription = nullptr; \
return NS_OK; \
} \
\
NS_IMETHODIMP \
_class::GetClassID(nsCID** _classID) \
{ \
*_classID = nullptr; \
return NS_OK; \
} \
\
NS_IMETHODIMP \
_class::GetFlags(uint32_t* _flags) \
{ \
*_flags = nsIClassInfo::THREADSAFE; \
return NS_OK; \
} \
\
NS_IMETHODIMP \
_class::GetClassIDNoAlloc(nsCID* _classIDNoAlloc) \
{ \
return NS_ERROR_NOT_AVAILABLE; \
}
#endif
