xpcom/base/nsISupportsImpl.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6 // IWYU pragma: private, include "nsISupports.h"
   7
   8 #ifndef nsISupportsImpl_h__
   9 #define nsISupportsImpl_h__
  10
  11 #include "nscore.h"
  12 #include "nsISupports.h"
  13 #include "nsISupportsUtils.h"
  14
  15 #if !defined(XPCOM_GLUE_AVOID_NSPR)
  16 #  include "prthread.h" /* needed for cargo-culting headers */
  17 #endif
  18
  19 #include "nsDebug.h"
  20 #include "nsXPCOM.h"
  21 #include <atomic>
  22 #include <type_traits>
  23 #include "mozilla/Attributes.h"
  24 #include "mozilla/Assertions.h"
  25 #include "mozilla/Atomics.h"
  26 #include "mozilla/Compiler.h"
  27 #include "mozilla/Likely.h"
  28 #include "mozilla/MacroArgs.h"
  29 #include "mozilla/MacroForEach.h"
  30
  31 #define MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(X)            \
  32   static_assert(!std::is_destructible_v<X>,              \
  33                 "Reference-counted class " #X            \
  34                 " should not have a public destructor. " \
  35                 "Make this class's destructor non-public");
  36
  37 inline nsISupports* ToSupports(decltype(nullptr)) { return nullptr; }
  38
  39 inline nsISupports* ToSupports(nsISupports* aSupports) { return aSupports; }
  40
  41 ////////////////////////////////////////////////////////////////////////////////
  42 // Macros to help detect thread-safety:
  43
  44 #ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
  45
  46 #  include "prthread.h" /* needed for thread-safety checks */
  47
  48 class nsAutoOwningThread {
  49  public:
  50   nsAutoOwningThread();
  51
  52   // We move the actual assertion checks out-of-line to minimize code bloat,
  53   // but that means we have to pass a non-literal string to MOZ_CRASH_UNSAFE.
  54   // To make that more safe, the public interface requires a literal string
  55   // and passes that to the private interface; we can then be assured that we
  56   // effectively are passing a literal string to MOZ_CRASH_UNSAFE.
  57   template <int N>
  58   void AssertOwnership(const char (&aMsg)[N]) const {
  59     AssertCurrentThreadOwnsMe(aMsg);
  60   }
  61
  62   bool IsCurrentThread() const;
  63
  64  private:
  65   void AssertCurrentThreadOwnsMe(const char* aMsg) const;
  66
  67   void* mThread;
  68 };
  69
  70 class nsISerialEventTarget;
  71 class nsAutoOwningEventTarget {
  72  public:
  73   nsAutoOwningEventTarget();
  74
  75   nsAutoOwningEventTarget(const nsAutoOwningEventTarget& aOther);
  76
  77   // Per https://en.cppreference.com/w/cpp/language/move_constructor
  78   // there's no implicitly-declared move constructor if there are user-declared
  79   // copy constructors, and we have one, immediately above.
  80
  81   nsAutoOwningEventTarget& operator=(const nsAutoOwningEventTarget& aRhs);
  82
  83   // Per https://en.cppreference.com/w/cpp/language/move_assignment
  84   // there's no implicitly-declared move assignment operator if there are
  85   // user-declared copy assignment operators, and we have one, immediately
  86   // above.
  87
  88   ~nsAutoOwningEventTarget();
  89
  90   // We move the actual assertion checks out-of-line to minimize code bloat,
  91   // but that means we have to pass a non-literal string to MOZ_CRASH_UNSAFE.
  92   // To make that more safe, the public interface requires a literal string
  93   // and passes that to the private interface; we can then be assured that we
  94   // effectively are passing a literal string to MOZ_CRASH_UNSAFE.
  95   template <int N>
  96   void AssertOwnership(const char (&aMsg)[N]) const {
  97     AssertCurrentThreadOwnsMe(aMsg);
  98   }
  99
 100   bool IsCurrentThread() const;
 101
 102  private:
 103   void AssertCurrentThreadOwnsMe(const char* aMsg) const;
 104
 105   // A raw pointer to avoid nsCOMPtr.h dependency.
 106   nsISerialEventTarget* mTarget;
 107 };
 108
 109 #  define NS_DECL_OWNINGTHREAD nsAutoOwningThread _mOwningThread;
 110 #  define NS_DECL_OWNINGEVENTTARGET nsAutoOwningEventTarget _mOwningThread;
 111 #  define NS_ASSERT_OWNINGTHREAD(_class) \
 112     _mOwningThread.AssertOwnership(#_class " not thread-safe")
 113 #else  // !MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
 114
 115 #  define NS_DECL_OWNINGTHREAD      /* nothing */
 116 #  define NS_DECL_OWNINGEVENTTARGET /* nothing */
 117 #  define NS_ASSERT_OWNINGTHREAD(_class) ((void)0)
 118
 119 #endif  // MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
 120
 121 // Macros for reference-count and constructor logging
 122
 123 #if defined(NS_BUILD_REFCNT_LOGGING)
 124
 125 #  define NS_LOG_ADDREF(_p, _rc, _type, _size) \
 126     NS_LogAddRef((_p), (_rc), (_type), (uint32_t)(_size))
 127
 128 #  define NS_LOG_RELEASE(_p, _rc, _type) NS_LogRelease((_p), (_rc), (_type))
 129
 130 #  define MOZ_ASSERT_CLASSNAME(_type)     \
 131     static_assert(std::is_class_v<_type>, \
 132                   "Token '" #_type "' is not a class type.")
 133
 134 #  define MOZ_ASSERT_NOT_ISUPPORTS(_type)                                     \
 135     static_assert(!std::is_base_of<nsISupports, _type>::value,                \
 136                   "nsISupports classes don't need to call MOZ_COUNT_CTOR or " \
 137                   "MOZ_COUNT_DTOR");
 138
 139 // Note that the following constructor/destructor logging macros are redundant
 140 // for refcounted objects that log via the NS_LOG_ADDREF/NS_LOG_RELEASE macros.
 141 // Refcount logging is preferred.
 142 #  define MOZ_COUNT_CTOR(_type)                       \
 143     do {                                              \
 144       MOZ_ASSERT_CLASSNAME(_type);                    \
 145       MOZ_ASSERT_NOT_ISUPPORTS(_type);                \
 146       NS_LogCtor((void*)this, #_type, sizeof(*this)); \
 147     } while (0)
 148
 149 #  define MOZ_COUNT_CTOR_INHERITED(_type, _base)                      \
 150     do {                                                              \
 151       MOZ_ASSERT_CLASSNAME(_type);                                    \
 152       MOZ_ASSERT_CLASSNAME(_base);                                    \
 153       MOZ_ASSERT_NOT_ISUPPORTS(_type);                                \
 154       NS_LogCtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
 155     } while (0)
 156
 157 #  define MOZ_LOG_CTOR(_ptr, _name, _size)   \
 158     do {                                     \
 159       NS_LogCtor((void*)_ptr, _name, _size); \
 160     } while (0)
 161
 162 #  define MOZ_COUNT_DTOR(_type)                       \
 163     do {                                              \
 164       MOZ_ASSERT_CLASSNAME(_type);                    \
 165       MOZ_ASSERT_NOT_ISUPPORTS(_type);                \
 166       NS_LogDtor((void*)this, #_type, sizeof(*this)); \
 167     } while (0)
 168
 169 #  define MOZ_COUNT_DTOR_INHERITED(_type, _base)                      \
 170     do {                                                              \
 171       MOZ_ASSERT_CLASSNAME(_type);                                    \
 172       MOZ_ASSERT_CLASSNAME(_base);                                    \
 173       MOZ_ASSERT_NOT_ISUPPORTS(_type);                                \
 174       NS_LogDtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
 175     } while (0)
 176
 177 #  define MOZ_LOG_DTOR(_ptr, _name, _size)   \
 178     do {                                     \
 179       NS_LogDtor((void*)_ptr, _name, _size); \
 180     } while (0)
 181
 182 #  define MOZ_COUNTED_DEFAULT_CTOR(_type) \
 183     _type() { MOZ_COUNT_CTOR(_type); }
 184
 185 #  define MOZ_COUNTED_DTOR_META(_type, _prefix, _postfix) \
 186     _prefix ~_type() _postfix { MOZ_COUNT_DTOR(_type); }
 187 #  define MOZ_COUNTED_DTOR_NESTED(_type, _nestedName) \
 188     ~_type() { MOZ_COUNT_DTOR(_nestedName); }
 189
 190 /* nsCOMPtr.h allows these macros to be defined by clients
 191  * These logging functions require dynamic_cast<void*>, so they don't
 192  * do anything useful if we don't have dynamic_cast<void*>.
 193  * Note: The explicit comparison to nullptr is needed to avoid warnings
 194  *       when _p is a nullptr itself. */
 195 #  define NSCAP_LOG_ASSIGNMENT(_c, _p) \
 196     if (_p != nullptr) NS_LogCOMPtrAddRef((_c), ToSupports(_p))
 197
 198 #  define NSCAP_LOG_RELEASE(_c, _p) \
 199     if (_p) NS_LogCOMPtrRelease((_c), ToSupports(_p))
 200
 201 #else /* !NS_BUILD_REFCNT_LOGGING */
 202
 203 #  define NS_LOG_ADDREF(_p, _rc, _type, _size)
 204 #  define NS_LOG_RELEASE(_p, _rc, _type)
 205 #  define MOZ_COUNT_CTOR(_type)
 206 #  define MOZ_COUNT_CTOR_INHERITED(_type, _base)
 207 #  define MOZ_LOG_CTOR(_ptr, _name, _size)
 208 #  define MOZ_COUNT_DTOR(_type)
 209 #  define MOZ_COUNT_DTOR_INHERITED(_type, _base)
 210 #  define MOZ_LOG_DTOR(_ptr, _name, _size)
 211 #  define MOZ_COUNTED_DEFAULT_CTOR(_type) _type() = default;
 212 #  define MOZ_COUNTED_DTOR_META(_type, _prefix, _postfix) \
 213     _prefix ~_type() _postfix = default;
 214 #  define MOZ_COUNTED_DTOR_NESTED(_type, _nestedName) ~_type() = default;
 215
 216 #endif /* NS_BUILD_REFCNT_LOGGING */
 217
 218 #define MOZ_COUNTED_DTOR(_type) MOZ_COUNTED_DTOR_META(_type, , )
 219 #define MOZ_COUNTED_DTOR_OVERRIDE(_type) \
 220   MOZ_COUNTED_DTOR_META(_type, , override)
 221 #define MOZ_COUNTED_DTOR_FINAL(_type) MOZ_COUNTED_DTOR_META(_type, , final)
 222 #define MOZ_COUNTED_DTOR_VIRTUAL(_type) MOZ_COUNTED_DTOR_META(_type, virtual, )
 223
 224 // Support for ISupports classes which interact with cycle collector.
 225
 226 #ifdef HAVE_64BIT_BUILD
 227 #  define NS_NUMBER_OF_FLAGS_IN_REFCNT 3
 228 #  define NS_IS_ON_MAINTHREAD (1 << 2)
 229 #else
 230 #  define NS_NUMBER_OF_FLAGS_IN_REFCNT 2
 231 #endif
 232
 233 #define NS_IN_PURPLE_BUFFER (1 << 0)
 234 #define NS_IS_PURPLE (1 << 1)
 235 #define NS_REFCOUNT_CHANGE (1 << NS_NUMBER_OF_FLAGS_IN_REFCNT)
 236 #define NS_REFCOUNT_VALUE(_val) (_val >> NS_NUMBER_OF_FLAGS_IN_REFCNT)
 237
 238 class nsCycleCollectingAutoRefCnt {
 239  public:
 240   typedef void (*Suspect)(void* aPtr, nsCycleCollectionParticipant* aCp,
 241                           nsCycleCollectingAutoRefCnt* aRefCnt,
 242                           bool* aShouldDelete);
 243
 244   nsCycleCollectingAutoRefCnt() : mRefCntAndFlags(0) {}
 245
 246   explicit nsCycleCollectingAutoRefCnt(uintptr_t aValue)
 247       : mRefCntAndFlags(aValue << NS_NUMBER_OF_FLAGS_IN_REFCNT) {}
 248
 249   nsCycleCollectingAutoRefCnt(const nsCycleCollectingAutoRefCnt&) = delete;
 250   void operator=(const nsCycleCollectingAutoRefCnt&) = delete;
 251
 252   MOZ_ALWAYS_INLINE uintptr_t incr(nsISupports* aOwner) {
 253     return incr(aOwner, nullptr);
 254   }
 255
 256   MOZ_ALWAYS_INLINE uintptr_t incr(void* aOwner,
 257                                    nsCycleCollectionParticipant* aCp) {
 258     mRefCntAndFlags += NS_REFCOUNT_CHANGE;
 259     mRefCntAndFlags &= ~NS_IS_PURPLE;
 260     // For incremental cycle collection, use the purple buffer to track objects
 261     // that have been AddRef'd.
 262     if (!IsInPurpleBuffer()) {
 263       mRefCntAndFlags |= NS_IN_PURPLE_BUFFER;
 264       // Refcount isn't zero, so Suspect won't delete anything.
 265       MOZ_ASSERT(get() > 0);
 266       NS_CycleCollectorSuspect3(aOwner, aCp, this, nullptr);
 267     }
 268     return NS_REFCOUNT_VALUE(mRefCntAndFlags);
 269   }
 270
 271   MOZ_ALWAYS_INLINE void stabilizeForDeletion() {
 272     // Set refcnt to 1 and mark us to be in the purple buffer.
 273     // This way decr won't call suspect again.
 274     mRefCntAndFlags = NS_REFCOUNT_CHANGE | NS_IN_PURPLE_BUFFER;
 275   }
 276
 277   MOZ_ALWAYS_INLINE uintptr_t decr(nsISupports* aOwner,
 278                                    bool* aShouldDelete = nullptr) {
 279     return decr(aOwner, nullptr, aShouldDelete);
 280   }
 281
 282   MOZ_ALWAYS_INLINE uintptr_t decr(void* aOwner,
 283                                    nsCycleCollectionParticipant* aCp,
 284                                    bool* aShouldDelete = nullptr) {
 285     MOZ_ASSERT(get() > 0);
 286     if (!IsInPurpleBuffer()) {
 287       mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
 288       mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
 289       uintptr_t retval = NS_REFCOUNT_VALUE(mRefCntAndFlags);
 290       // Suspect may delete 'aOwner' and 'this'!
 291       NS_CycleCollectorSuspect3(aOwner, aCp, this, aShouldDelete);
 292       return retval;
 293     }
 294     mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
 295     mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
 296     return NS_REFCOUNT_VALUE(mRefCntAndFlags);
 297   }
 298
 299   MOZ_ALWAYS_INLINE void RemovePurple() {
 300     MOZ_ASSERT(IsPurple(), "must be purple");
 301     mRefCntAndFlags &= ~NS_IS_PURPLE;
 302   }
 303
 304   MOZ_ALWAYS_INLINE void RemoveFromPurpleBuffer() {
 305     MOZ_ASSERT(IsInPurpleBuffer());
 306     mRefCntAndFlags &= ~(NS_IS_PURPLE | NS_IN_PURPLE_BUFFER);
 307   }
 308
 309   MOZ_ALWAYS_INLINE bool IsPurple() const {
 310     return !!(mRefCntAndFlags & NS_IS_PURPLE);
 311   }
 312
 313   MOZ_ALWAYS_INLINE bool IsInPurpleBuffer() const {
 314     return !!(mRefCntAndFlags & NS_IN_PURPLE_BUFFER);
 315   }
 316
 317   // Cycle collected objects can only be used on a single thread, so if we ever
 318   // see an object on the main thread, it will always be on the main thread.
 319   // The cycle collector then uses this information to utilize faster nursery
 320   // purple buffer on the main thread.
 321   // The method works only on 64 bit systems.
 322   MOZ_ALWAYS_INLINE void SetIsOnMainThread() {
 323 #ifdef HAVE_64BIT_BUILD
 324     mRefCntAndFlags |= NS_IS_ON_MAINTHREAD;
 325 #endif
 326   }
 327
 328 #ifdef HAVE_64BIT_BUILD
 329   // The NS_IS_ON_MAINTHREAD flag only exists on 64-bit builds.
 330   MOZ_ALWAYS_INLINE bool IsOnMainThread() {
 331     return !!(mRefCntAndFlags & NS_IS_ON_MAINTHREAD);
 332   }
 333 #endif
 334
 335   MOZ_ALWAYS_INLINE nsrefcnt get() const {
 336     return NS_REFCOUNT_VALUE(mRefCntAndFlags);
 337   }
 338
 339   MOZ_ALWAYS_INLINE operator nsrefcnt() const { return get(); }
 340
 341  private:
 342   uintptr_t mRefCntAndFlags;
 343 };
 344
 345 class nsAutoRefCnt {
 346  public:
 347   nsAutoRefCnt() : mValue(0) {}
 348   explicit nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
 349
 350   nsAutoRefCnt(const nsAutoRefCnt&) = delete;
 351   void operator=(const nsAutoRefCnt&) = delete;
 352
 353   // only support prefix increment/decrement
 354   nsrefcnt operator++() { return ++mValue; }
 355   nsrefcnt operator--() { return --mValue; }
 356
 357   nsrefcnt operator=(nsrefcnt aValue) { return (mValue = aValue); }
 358   operator nsrefcnt() const { return mValue; }
 359   nsrefcnt get() const { return mValue; }
 360
 361   static const bool isThreadSafe = false;
 362
 363  private:
 364   nsrefcnt operator++(int) = delete;
 365   nsrefcnt operator--(int) = delete;
 366   nsrefcnt mValue;
 367 };
 368
 369 namespace mozilla {
 370 class ThreadSafeAutoRefCnt {
 371  public:
 372   ThreadSafeAutoRefCnt() : mValue(0) {}
 373   explicit ThreadSafeAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
 374
 375   ThreadSafeAutoRefCnt(const ThreadSafeAutoRefCnt&) = delete;
 376   void operator=(const ThreadSafeAutoRefCnt&) = delete;
 377
 378   // only support prefix increment/decrement
 379   MOZ_ALWAYS_INLINE nsrefcnt operator++() {
 380     // Memory synchronization is not required when incrementing a
 381     // reference count.  The first increment of a reference count on a
 382     // thread is not important, since the first use of the object on a
 383     // thread can happen before it.  What is important is the transfer
 384     // of the pointer to that thread, which may happen prior to the
 385     // first increment on that thread.  The necessary memory
 386     // synchronization is done by the mechanism that transfers the
 387     // pointer between threads.
 388     return mValue.fetch_add(1, std::memory_order_relaxed) + 1;
 389   }
 390   MOZ_ALWAYS_INLINE nsrefcnt operator--() {
 391     // Since this may be the last release on this thread, we need
 392     // release semantics so that prior writes on this thread are visible
 393     // to the thread that destroys the object when it reads mValue with
 394     // acquire semantics.
 395     nsrefcnt result = mValue.fetch_sub(1, std::memory_order_release) - 1;
 396     if (result == 0) {
 397       // We're going to destroy the object on this thread, so we need
 398       // acquire semantics to synchronize with the memory released by
 399       // the last release on other threads, that is, to ensure that
 400       // writes prior to that release are now visible on this thread.
 401 #ifdef MOZ_TSAN
 402       // TSan doesn't understand std::atomic_thread_fence, so in order
 403       // to avoid a false positive for every time a refcounted object
 404       // is deleted, we replace the fence with an atomic operation.
 405       mValue.load(std::memory_order_acquire);
 406 #else
 407       std::atomic_thread_fence(std::memory_order_acquire);
 408 #endif
 409     }
 410     return result;
 411   }
 412
 413   MOZ_ALWAYS_INLINE nsrefcnt operator=(nsrefcnt aValue) {
 414     // Use release semantics since we're not sure what the caller is
 415     // doing.
 416     mValue.store(aValue, std::memory_order_release);
 417     return aValue;
 418   }
 419   MOZ_ALWAYS_INLINE operator nsrefcnt() const { return get(); }
 420   MOZ_ALWAYS_INLINE nsrefcnt get() const {
 421     // Use acquire semantics since we're not sure what the caller is
 422     // doing.
 423     return mValue.load(std::memory_order_acquire);
 424   }
 425
 426   static const bool isThreadSafe = true;
 427
 428  private:
 429   nsrefcnt operator++(int) = delete;
 430   nsrefcnt operator--(int) = delete;
 431   std::atomic<nsrefcnt> mValue;
 432 };
 433
 434 namespace detail {
 435
 436 // Type trait indicating whether a given XPCOM interface class may only be
 437 // implemented by types with threadsafe refcounts. This is specialized for
 438 // classes with the `rust_sync` annotation within XPIDL-generated header files,
 439 // and checked within macro-generated QueryInterface implementations.
 440 template <typename T>
 441 class InterfaceNeedsThreadSafeRefCnt : public std::false_type {};
 442
 443 }
 444 }  // namespace mozilla
 445
 446 ///////////////////////////////////////////////////////////////////////////////
 447
 448 /**
 449  * Declare the reference count variable and the implementations of the
 450  * AddRef and QueryInterface methods.
 451  */
 452
 453 #define NS_DECL_ISUPPORTS                                                 \
 454  public:                                                                  \
 455   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override; \
 456   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
 457   NS_IMETHOD_(MozExternalRefCountType) Release(void) override;            \
 458   using HasThreadSafeRefCnt = std::false_type;                            \
 459                                                                           \
 460  protected:                                                               \
 461   nsAutoRefCnt mRefCnt;                                                   \
 462   NS_DECL_OWNINGTHREAD                                                    \
 463  public:
 464
 465 #define NS_DECL_ISUPPORTS_ONEVENTTARGET                                   \
 466  public:                                                                  \
 467   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override; \
 468   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
 469   NS_IMETHOD_(MozExternalRefCountType) Release(void) override;            \
 470   using HasThreadSafeRefCnt = std::false_type;                            \
 471                                                                           \
 472  protected:                                                               \
 473   nsAutoRefCnt mRefCnt;                                                   \
 474   NS_DECL_OWNINGEVENTTARGET                                               \
 475  public:
 476
 477 #define NS_DECL_THREADSAFE_ISUPPORTS                                      \
 478  public:                                                                  \
 479   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override; \
 480   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
 481   NS_IMETHOD_(MozExternalRefCountType) Release(void) override;            \
 482   using HasThreadSafeRefCnt = std::true_type;                             \
 483                                                                           \
 484  protected:                                                               \
 485   ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                \
 486   NS_DECL_OWNINGTHREAD                                                    \
 487  public:
 488
 489 #define NS_DECL_CYCLE_COLLECTING_ISUPPORTS          \
 490   NS_DECL_CYCLE_COLLECTING_ISUPPORTS_META(override) \
 491   NS_IMETHOD_(void) DeleteCycleCollectable(void);   \
 492                                                     \
 493  public:
 494
 495 #define NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL  \
 496   NS_DECL_CYCLE_COLLECTING_ISUPPORTS_META(final)  \
 497   NS_IMETHOD_(void) DeleteCycleCollectable(void); \
 498                                                   \
 499  public:
 500
 501 #define NS_DECL_CYCLE_COLLECTING_ISUPPORTS_META(...)                         \
 502  public:                                                                     \
 503   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) __VA_ARGS__; \
 504   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) __VA_ARGS__;             \
 505   NS_IMETHOD_(MozExternalRefCountType) Release(void) __VA_ARGS__;            \
 506   using HasThreadSafeRefCnt = std::false_type;                               \
 507                                                                              \
 508  protected:                                                                  \
 509   nsCycleCollectingAutoRefCnt mRefCnt;                                       \
 510   NS_DECL_OWNINGTHREAD                                                       \
 511  public:
 512
 513 ///////////////////////////////////////////////////////////////////////////////
 514
 515 /*
 516  * Implementation of AddRef and Release for non-nsISupports (ie "native")
 517  * cycle-collected classes that use the purple buffer to avoid leaks.
 518  */
 519
 520 #define NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                 \
 521   MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
 522   MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                        \
 523   NS_ASSERT_OWNINGTHREAD(_class);                                             \
 524   nsrefcnt count =                                                            \
 525       mRefCnt.incr(static_cast<void*>(this),                                  \
 526                    _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
 527   NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
 528   return count;
 529
 530 #define NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                \
 531   MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
 532   NS_ASSERT_OWNINGTHREAD(_class);                                             \
 533   nsrefcnt count =                                                            \
 534       mRefCnt.decr(static_cast<void*>(this),                                  \
 535                    _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
 536   NS_LOG_RELEASE(this, count, #_class);                                       \
 537   return count;
 538
 539 #define NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(_class)       \
 540   NS_METHOD_(MozExternalRefCountType) _class::AddRef(void) { \
 541     NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                    \
 542   }
 543
 544 #define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE_WITH_LAST_RELEASE(_class,      \
 545                                                                   _last)       \
 546   NS_METHOD_(MozExternalRefCountType) _class::Release(void) {                  \
 547     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                           \
 548     NS_ASSERT_OWNINGTHREAD(_class);                                            \
 549     bool shouldDelete = false;                                                 \
 550     nsrefcnt count =                                                           \
 551         mRefCnt.decr(static_cast<void*>(this),                                 \
 552                      _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant(), \
 553                      &shouldDelete);                                           \
 554     NS_LOG_RELEASE(this, count, #_class);                                      \
 555     if (count == 0) {                                                          \
 556       mRefCnt.incr(static_cast<void*>(this),                                   \
 557                    _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
 558       _last;                                                                   \
 559       mRefCnt.decr(static_cast<void*>(this),                                   \
 560                    _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
 561       if (shouldDelete) {                                                      \
 562         mRefCnt.stabilizeForDeletion();                                        \
 563         DeleteCycleCollectable();                                              \
 564       }                                                                        \
 565     }                                                                          \
 566     return count;                                                              \
 567   }
 568
 569 #define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE(_class)       \
 570   NS_METHOD_(MozExternalRefCountType) _class::Release(void) { \
 571     NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                    \
 572   }
 573
 574 #define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(_class) \
 575   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_META(_class, NS_METHOD_)
 576
 577 #define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_VIRTUAL(_class) \
 578   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_META(_class, NS_IMETHOD_)
 579
 580 #define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_INHERITED(_class)  \
 581   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_META(_class, NS_METHOD_, \
 582                                                           override)
 583
 584 #define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING_META(_class, _decl, \
 585                                                                 ...)           \
 586  public:                                                                       \
 587   _decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__{                     \
 588       NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)} _decl(MozExternalRefCountType)    \
 589       Release(void) __VA_ARGS__ {                                              \
 590     NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                     \
 591   }                                                                            \
 592   using HasThreadSafeRefCnt = std::false_type;                                 \
 593                                                                                \
 594  protected:                                                                    \
 595   nsCycleCollectingAutoRefCnt mRefCnt;                                         \
 596   NS_DECL_OWNINGTHREAD                                                         \
 597  public:
 598
 599 ///////////////////////////////////////////////////////////////////////////////
 600
 601 /**
 602  * Use this macro to declare and implement the AddRef & Release methods for a
 603  * given non-XPCOM <i>_class</i>.
 604  *
 605  * @param _class The name of the class implementing the method
 606  * @param _destroy A statement that is executed when the object's
 607  *   refcount drops to zero.
 608  * @param _decl Name of the macro to be used for the return type of the
 609  *   AddRef & Release methods (typically NS_IMETHOD_ or NS_METHOD_).
 610  * @param optional override Mark the AddRef & Release methods as overrides.
 611  */
 612 #define NS_INLINE_DECL_REFCOUNTING_META(_class, _decl, _destroy, _owning, ...) \
 613  public:                                                                       \
 614   _decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {                    \
 615     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                 \
 616     MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                       \
 617     NS_ASSERT_OWNINGTHREAD(_class);                                            \
 618     ++mRefCnt;                                                                 \
 619     NS_LOG_ADDREF(this, mRefCnt, #_class, sizeof(*this));                      \
 620     return mRefCnt;                                                            \
 621   }                                                                            \
 622   _decl(MozExternalRefCountType) Release(void) __VA_ARGS__ {                   \
 623     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                           \
 624     NS_ASSERT_OWNINGTHREAD(_class);                                            \
 625     --mRefCnt;                                                                 \
 626     NS_LOG_RELEASE(this, mRefCnt, #_class);                                    \
 627     if (mRefCnt == 0) {                                                        \
 628       mRefCnt = 1; /* stabilize */                                             \
 629       _destroy;                                                                \
 630       return 0;                                                                \
 631     }                                                                          \
 632     return mRefCnt;                                                            \
 633   }                                                                            \
 634   using HasThreadSafeRefCnt = std::false_type;                                 \
 635                                                                                \
 636  protected:                                                                    \
 637   nsAutoRefCnt mRefCnt;                                                        \
 638   _owning public:
 639
 640 /**
 641  * Use this macro to declare and implement the AddRef & Release methods for a
 642  * given non-XPCOM <i>_class</i>.
 643  *
 644  * @param _class The name of the class implementing the method
 645  * @param _destroy A statement that is executed when the object's
 646  *   refcount drops to zero.
 647  * @param optional override Mark the AddRef & Release methods as overrides.
 648  */
 649 #define NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, _destroy, ...) \
 650   NS_INLINE_DECL_REFCOUNTING_META(_class, NS_METHOD_, _destroy,        \
 651                                   NS_DECL_OWNINGTHREAD, __VA_ARGS__)
 652
 653 /**
 654  * Like NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY with AddRef & Release declared
 655  * virtual.
 656  */
 657 #define NS_INLINE_DECL_VIRTUAL_REFCOUNTING_WITH_DESTROY(_class, _destroy, ...) \
 658   NS_INLINE_DECL_REFCOUNTING_META(_class, NS_IMETHOD_, _destroy,               \
 659                                   NS_DECL_OWNINGTHREAD, __VA_ARGS__)
 660
 661 /**
 662  * Use this macro to declare and implement the AddRef & Release methods for a
 663  * given non-XPCOM <i>_class</i>.
 664  *
 665  * @param _class The name of the class implementing the method
 666  * @param optional override Mark the AddRef & Release methods as overrides.
 667  */
 668 #define NS_INLINE_DECL_REFCOUNTING(_class, ...) \
 669   NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, delete (this), __VA_ARGS__)
 670
 671 /**
 672  * Like NS_INLINE_DECL_REFCOUNTING, however the thread safety check will work
 673  * with any nsISerialEventTarget. This is a workaround until bug 1648031 is
 674  * properly resolved. Once this is done, it will be possible to use
 675  * NS_INLINE_DECL_REFCOUNTING under all circumstances.
 676  */
 677 #define NS_INLINE_DECL_REFCOUNTING_ONEVENTTARGET(_class, ...)        \
 678   NS_INLINE_DECL_REFCOUNTING_META(_class, NS_METHOD_, delete (this), \
 679                                   NS_DECL_OWNINGEVENTTARGET, __VA_ARGS__)
 680
 681 #define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, _decl, _destroy, \
 682                                                    ...)                     \
 683  public:                                                                    \
 684   _decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {                 \
 685     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                              \
 686     MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                    \
 687     nsrefcnt count = ++mRefCnt;                                             \
 688     NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                     \
 689     return (nsrefcnt)count;                                                 \
 690   }                                                                         \
 691   _decl(MozExternalRefCountType) Release(void) __VA_ARGS__ {                \
 692     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                        \
 693     nsrefcnt count = --mRefCnt;                                             \
 694     NS_LOG_RELEASE(this, count, #_class);                                   \
 695     if (count == 0) {                                                       \
 696       _destroy;                                                             \
 697       return 0;                                                             \
 698     }                                                                       \
 699     return count;                                                           \
 700   }                                                                         \
 701   using HasThreadSafeRefCnt = std::true_type;                               \
 702                                                                             \
 703  protected:                                                                 \
 704   ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                  \
 705                                                                             \
 706  public:
 707
 708 /**
 709  * Use this macro to declare and implement the AddRef & Release methods for a
 710  * given non-XPCOM <i>_class</i> in a threadsafe manner.
 711  *
 712  * DOES NOT DO REFCOUNT STABILIZATION!
 713  *
 714  * @param _class The name of the class implementing the method
 715  * @param _destroy A statement that is executed when the object's
 716  *   refcount drops to zero.
 717  * @param optional override Mark the AddRef & Release methods as overrides.
 718  */
 719 #define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DESTROY(_class, _destroy, \
 720                                                            ...)              \
 721   NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_METHOD_, _destroy,   \
 722                                              __VA_ARGS__)
 723
 724 /**
 725  * Like NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DESTROY with AddRef & Release
 726  * declared virtual.
 727  */
 728 #define NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING_WITH_DESTROY(         \
 729     _class, _destroy, ...)                                                  \
 730   NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_IMETHOD_, _destroy, \
 731                                              __VA_ARGS__)
 732
 733 /**
 734  * Use this macro to declare and implement the AddRef & Release methods for a
 735  * given non-XPCOM <i>_class</i> in a threadsafe manner.
 736  *
 737  * DOES NOT DO REFCOUNT STABILIZATION!
 738  *
 739  * @param _class The name of the class implementing the method
 740  * @param optional override Mark the AddRef & Release methods as overrides.
 741  */
 742 #define NS_INLINE_DECL_THREADSAFE_REFCOUNTING(_class, ...)                  \
 743   NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DESTROY(_class, delete (this), \
 744                                                      __VA_ARGS__)
 745
 746 /**
 747  * Like NS_INLINE_DECL_THREADSAFE_REFCOUNTING with AddRef & Release declared
 748  * virtual.
 749  */
 750 #define NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING(_class, ...) \
 751   NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING_WITH_DESTROY(      \
 752       _class, delete (this), __VA_ARGS__)
 753
 754 #if !defined(XPCOM_GLUE_AVOID_NSPR)
 755 class nsISerialEventTarget;
 756 namespace mozilla {
 757 // Forward-declare `GetMainThreadSerialEventTarget`, as `nsISupportsImpl.h`
 758 // cannot include `nsThreadUtils.h`.
 759 nsISerialEventTarget* GetMainThreadSerialEventTarget();
 760
 761 namespace detail {
 762 using DeleteVoidFunction = void(void*);
 763 void ProxyDeleteVoid(const char* aRunnableName,
 764                      nsISerialEventTarget* aEventTarget, void* aSelf,
 765                      DeleteVoidFunction* aDeleteFunc);
 766 }  // namespace detail
 767 }  // namespace mozilla
 768
 769 /**
 770  * Helper for _WITH_DELETE_ON_EVENT_TARGET threadsafe refcounting macros which
 771  * provides an implementation of `_destroy`
 772  */
 773 #  define NS_PROXY_DELETE_TO_EVENT_TARGET(_class, _target) \
 774     ::mozilla::detail::ProxyDeleteVoid(                    \
 775         "ProxyDelete " #_class, _target, this,             \
 776         [](void* self) { delete static_cast<_class*>(self); })
 777
 778 /**
 779  * Use this macro to declare and implement the AddRef & Release methods for a
 780  * given non-XPCOM <i>_class</i> in a threadsafe manner, ensuring the
 781  * destructor runs on a specific nsISerialEventTarget.
 782  *
 783  * DOES NOT DO REFCOUNT STABILIZATION!
 784  *
 785  * @param _class The name of the class implementing the method
 786  * @param _target nsISerialEventTarget to run the class's destructor on
 787  * @param optional override Mark the AddRef & Release methods as overrides
 788  */
 789 #  define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DELETE_ON_EVENT_TARGET( \
 790       _class, _target, ...)                                                  \
 791     NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DESTROY(                      \
 792         _class, NS_PROXY_DELETE_TO_EVENT_TARGET(_class, _target), __VA_ARGS__)
 793
 794 /**
 795  * Use this macro to declare and implement the AddRef & Release methods for a
 796  * given non-XPCOM <i>_class</i> in a threadsafe manner, ensuring the
 797  * destructor runs on the main thread.
 798  *
 799  * DOES NOT DO REFCOUNT STABILIZATION!
 800  *
 801  * @param _class The name of the class implementing the method
 802  * @param optional override Mark the AddRef & Release methods as overrides
 803  */
 804 #  define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DELETE_ON_MAIN_THREAD( \
 805       _class, ...)                                                          \
 806     NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DELETE_ON_EVENT_TARGET(      \
 807         _class, ::mozilla::GetMainThreadSerialEventTarget(), __VA_ARGS__)
 808 #endif
 809
 810 /**
 811  * Use this macro in interface classes that you want to be able to reference
 812  * using RefPtr, but don't want to provide a refcounting implemenation. The
 813  * refcounting implementation can be provided by concrete subclasses that
 814  * implement the interface.
 815  */
 816 #define NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING           \
 817  public:                                                  \
 818   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) = 0;  \
 819   NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0; \
 820                                                           \
 821  public:
 822
 823 /**
 824  * Use this macro to implement the AddRef method for a given <i>_class</i>
 825  * @param _class The name of the class implementing the method
 826  * @param _name The class name to be passed to XPCOM leak checking
 827  */
 828 #define NS_IMPL_NAMED_ADDREF(_class, _name)                      \
 829   NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) { \
 830     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                   \
 831     MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");         \
 832     MOZ_ASSERT(_name != nullptr, "Must specify a name");         \
 833     if (!mRefCnt.isThreadSafe) NS_ASSERT_OWNINGTHREAD(_class);   \
 834     nsrefcnt count = ++mRefCnt;                                  \
 835     NS_LOG_ADDREF(this, count, _name, sizeof(*this));            \
 836     return count;                                                \
 837   }
 838
 839 /**
 840  * Use this macro to implement the AddRef method for a given <i>_class</i>
 841  * @param _class The name of the class implementing the method
 842  */
 843 #define NS_IMPL_ADDREF(_class) NS_IMPL_NAMED_ADDREF(_class, #_class)
 844
 845 /**
 846  * Use this macro to implement the AddRef method for a given <i>_class</i>
 847  * implemented as a wholly owned aggregated object intended to implement
 848  * interface(s) for its owner
 849  * @param _class The name of the class implementing the method
 850  * @param _aggregator the owning/containing object
 851  */
 852 #define NS_IMPL_ADDREF_USING_AGGREGATOR(_class, _aggregator)     \
 853   NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) { \
 854     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                   \
 855     MOZ_ASSERT(_aggregator, "null aggregator");                  \
 856     return (_aggregator)->AddRef();                              \
 857   }
 858
 859 // We decrement the refcnt before logging the actual release, but when logging
 860 // named things, accessing the name may not be valid after the refcnt
 861 // decrement, because the object may have been destroyed on a different thread.
 862 // Use this macro to ensure that we have a local copy of the name prior to
 863 // the refcnt decrement.  (We use a macro to make absolutely sure the name
 864 // isn't loaded in builds where it wouldn't be used.)
 865 #ifdef NS_BUILD_REFCNT_LOGGING
 866 #  define NS_LOAD_NAME_BEFORE_RELEASE(localname, _name) \
 867     const char* const localname = _name
 868 #else
 869 #  define NS_LOAD_NAME_BEFORE_RELEASE(localname, _name)
 870 #endif
 871
 872 /**
 873  * Use this macro to implement the Release method for a given
 874  * <i>_class</i>.
 875  * @param _class The name of the class implementing the method
 876  * @param _name The class name to be passed to XPCOM leak checking
 877  * @param _destroy A statement that is executed when the object's
 878  *   refcount drops to zero.
 879  *
 880  * For example,
 881  *
 882  *   NS_IMPL_RELEASE_WITH_DESTROY(Foo, "Foo", Destroy(this))
 883  *
 884  * will cause
 885  *
 886  *   Destroy(this);
 887  *
 888  * to be invoked when the object's refcount drops to zero. This
 889  * allows for arbitrary teardown activity to occur (e.g., deallocation
 890  * of object allocated with placement new).
 891  */
 892 #define NS_IMPL_NAMED_RELEASE_WITH_DESTROY(_class, _name, _destroy) \
 893   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) {   \
 894     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                \
 895     MOZ_ASSERT(_name != nullptr, "Must specify a name");            \
 896     if (!mRefCnt.isThreadSafe) NS_ASSERT_OWNINGTHREAD(_class);      \
 897     NS_LOAD_NAME_BEFORE_RELEASE(nametmp, _name);                    \
 898     nsrefcnt count = --mRefCnt;                                     \
 899     NS_LOG_RELEASE(this, count, nametmp);                           \
 900     if (count == 0) {                                               \
 901       mRefCnt = 1; /* stabilize */                                  \
 902       _destroy;                                                     \
 903       return 0;                                                     \
 904     }                                                               \
 905     return count;                                                   \
 906   }
 907
 908 #define NS_IMPL_RELEASE_WITH_DESTROY(_class, _destroy) \
 909   NS_IMPL_NAMED_RELEASE_WITH_DESTROY(_class, #_class, _destroy)
 910
 911 /**
 912  * Use this macro to implement the Release method for a given <i>_class</i>
 913  * @param _class The name of the class implementing the method
 914  *
 915  * A note on the 'stabilization' of the refcnt to one. At that point,
 916  * the object's refcount will have gone to zero. The object's
 917  * destructor may trigger code that attempts to QueryInterface() and
 918  * Release() 'this' again. Doing so will temporarily increment and
 919  * decrement the refcount. (Only a logic error would make one try to
 920  * keep a permanent hold on 'this'.)  To prevent re-entering the
 921  * destructor, we make sure that no balanced refcounting can return
 922  * the refcount to |0|.
 923  */
 924 #define NS_IMPL_RELEASE(_class) \
 925   NS_IMPL_RELEASE_WITH_DESTROY(_class, delete (this))
 926
 927 #define NS_IMPL_NAMED_RELEASE(_class, _name) \
 928   NS_IMPL_NAMED_RELEASE_WITH_DESTROY(_class, _name, delete (this))
 929
 930 /**
 931  * Use this macro to implement the Release method for a given <i>_class</i>
 932  * implemented as a wholly owned aggregated object intended to implement
 933  * interface(s) for its owner
 934  * @param _class The name of the class implementing the method
 935  * @param _aggregator the owning/containing object
 936  */
 937 #define NS_IMPL_RELEASE_USING_AGGREGATOR(_class, _aggregator)     \
 938   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) { \
 939     MOZ_ASSERT(_aggregator, "null aggregator");                   \
 940     return (_aggregator)->Release();                              \
 941   }
 942
 943 #define NS_IMPL_CYCLE_COLLECTING_ADDREF(_class)                              \
 944   NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void) {             \
 945     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                               \
 946     MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                     \
 947     NS_ASSERT_OWNINGTHREAD(_class);                                          \
 948     nsISupports* base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
 949     nsrefcnt count = mRefCnt.incr(base);                                     \
 950     NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                      \
 951     return count;                                                            \
 952   }
 953
 954 #define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, _destroy)      \
 955   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) {            \
 956     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                         \
 957     NS_ASSERT_OWNINGTHREAD(_class);                                          \
 958     nsISupports* base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
 959     nsrefcnt count = mRefCnt.decr(base);                                     \
 960     NS_LOG_RELEASE(this, count, #_class);                                    \
 961     return count;                                                            \
 962   }                                                                          \
 963   NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) { _destroy; }
 964
 965 #define NS_IMPL_CYCLE_COLLECTING_RELEASE(_class) \
 966   NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, delete (this))
 967
 968 // _LAST_RELEASE can be useful when certain resources should be released
 969 // as soon as we know the object will be deleted.
 970 #define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(_class, _last)    \
 971   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) {            \
 972     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                         \
 973     NS_ASSERT_OWNINGTHREAD(_class);                                          \
 974     bool shouldDelete = false;                                               \
 975     nsISupports* base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
 976     nsrefcnt count = mRefCnt.decr(base, &shouldDelete);                      \
 977     NS_LOG_RELEASE(this, count, #_class);                                    \
 978     if (count == 0) {                                                        \
 979       mRefCnt.incr(base);                                                    \
 980       _last;                                                                 \
 981       mRefCnt.decr(base);                                                    \
 982       if (shouldDelete) {                                                    \
 983         mRefCnt.stabilizeForDeletion();                                      \
 984         DeleteCycleCollectable();                                            \
 985       }                                                                      \
 986     }                                                                        \
 987     return count;                                                            \
 988   }                                                                          \
 989   NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) { delete this; }
 990
 991 // This macro is same as NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE
 992 // except it doesn't have DeleteCycleCollectable.
 993 #define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE_AND_DESTROY(      \
 994     _class, _last, _destroy)                                                 \
 995   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) {            \
 996     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                         \
 997     NS_ASSERT_OWNINGTHREAD(_class);                                          \
 998     bool shouldDelete = false;                                               \
 999     nsISupports* base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
1000     nsrefcnt count = mRefCnt.decr(base, &shouldDelete);                      \
1001     NS_LOG_RELEASE(this, count, #_class);                                    \
1002     if (count == 0) {                                                        \
1003       mRefCnt.incr(base);                                                    \
1004       _last;                                                                 \
1005       mRefCnt.decr(base);                                                    \
1006       if (shouldDelete) {                                                    \
1007         mRefCnt.stabilizeForDeletion();                                      \
1008         DeleteCycleCollectable();                                            \
1009       }                                                                      \
1010     }                                                                        \
1011     return count;                                                            \
1012   }                                                                          \
1013   NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) { _destroy; }
1014
1015 // _WITH_INTERRUPTABLE_LAST_RELEASE can be useful when certain resources
1016 // should be released as soon as we know the object will be deleted and the
1017 // instance may be cached for reuse.
1018 // _last is performed for cleaning up its resources.  Then, _maybeInterrupt is
1019 // tested and when it returns true, this stops deleting the instance.
1020 // (Note that it's not allowed to grab the instance with nsCOMPtr or RefPtr
1021 // during _last is performed.)
1022 // Therefore, when _maybeInterrupt returns true, the instance has to be grabbed
1023 // by nsCOMPtr or RefPtr.
1024 #define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_INTERRUPTABLE_LAST_RELEASE(    \
1025     _class, _last, _maybeInterrupt)                                          \
1026   NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void) {            \
1027     MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                         \
1028     NS_ASSERT_OWNINGTHREAD(_class);                                          \
1029     bool shouldDelete = false;                                               \
1030     nsISupports* base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
1031     nsrefcnt count = mRefCnt.decr(base, &shouldDelete);                      \
1032     NS_LOG_RELEASE(this, count, #_class);                                    \
1033     if (count == 0) {                                                        \
1034       mRefCnt.incr(base);                                                    \
1035       _last;                                                                 \
1036       mRefCnt.decr(base);                                                    \
1037       if (_maybeInterrupt) {                                                 \
1038         MOZ_ASSERT(mRefCnt.get() > 0);                                       \
1039         return mRefCnt.get();                                                \
1040       }                                                                      \
1041       if (shouldDelete) {                                                    \
1042         mRefCnt.stabilizeForDeletion();                                      \
1043         DeleteCycleCollectable();                                            \
1044       }                                                                      \
1045     }                                                                        \
1046     return count;                                                            \
1047   }                                                                          \
1048   NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void) { delete this; }
1049
1050 ///////////////////////////////////////////////////////////////////////////////
1051
1052 namespace mozilla::detail {
1053
1054 // Helper which is roughly equivalent to NS_GET_IID, which also performs static
1055 // assertions that `Class` is allowed to implement the given XPCOM interface.
1056 //
1057 // These assertions are done like this to allow them to be used within the
1058 // `NS_INTERFACE_TABLE_ENTRY` macro, though they are also used in
1059 // `NS_IMPL_QUERY_BODY`.
1060 template <typename Class, typename Interface>
1061 constexpr const nsIID& GetImplementedIID() {
1062   if constexpr (mozilla::detail::InterfaceNeedsThreadSafeRefCnt<
1063                     Interface>::value) {
1064     static_assert(Class::HasThreadSafeRefCnt::value,
1065                   "Cannot implement a threadsafe interface with "
1066                   "non-threadsafe refcounting!");
1067   }
1068   return NS_GET_TEMPLATE_IID(Interface);
1069 }
1070
1071 template <typename Class, typename Interface>
1072 constexpr const nsIID& kImplementedIID = GetImplementedIID<Class, Interface>();
1073
1074 }
1075
1076 /**
1077  * There are two ways of implementing QueryInterface, and we use both:
1078  *
1079  * Table-driven QueryInterface uses a static table of IID->offset mappings
1080  * and a shared helper function. Using it tends to reduce codesize and improve
1081  * runtime performance (due to processor cache hits).
1082  *
1083  * Macro-driven QueryInterface generates a QueryInterface function directly
1084  * using common macros. This is necessary if special QueryInterface features
1085  * are being used (such as tearoffs and conditional interfaces).
1086  *
1087  * These methods can be combined into a table-driven function call followed
1088  * by custom code for tearoffs and conditionals.
1089  */
1090
1091 struct QITableEntry {
1092   const nsIID* iid;  // null indicates end of the QITableEntry array
1093   int32_t offset;
1094 };
1095
1096 nsresult NS_FASTCALL NS_TableDrivenQI(void* aThis, REFNSIID aIID,
1097                                       void** aInstancePtr,
1098                                       const QITableEntry* aEntries);
1099
1100 /**
1101  * Implement table-driven queryinterface
1102  */
1103
1104 #define NS_INTERFACE_TABLE_HEAD(_class)                                      \
1105   NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr) { \
1106     NS_ASSERTION(aInstancePtr,                                               \
1107                  "QueryInterface requires a non-NULL destination!");         \
1108     nsresult rv = NS_ERROR_FAILURE;
1109
1110 #define NS_INTERFACE_TABLE_BEGIN static const QITableEntry table[] = {
1111 #define NS_INTERFACE_TABLE_ENTRY(_class, _interface)                        \
1112   {&mozilla::detail::kImplementedIID<_class, _interface>,                   \
1113    int32_t(                                                                 \
1114        reinterpret_cast<char*>(static_cast<_interface*>((_class*)0x1000)) - \
1115        reinterpret_cast<char*>((_class*)0x1000))},
1116
1117 #define NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(_class, _interface, _implClass) \
1118   {&mozilla::detail::kImplementedIID<_class, _interface>,                  \
1119    int32_t(reinterpret_cast<char*>(static_cast<_interface*>(               \
1120                static_cast<_implClass*>((_class*)0x1000))) -               \
1121            reinterpret_cast<char*>((_class*)0x1000))},
1122
1123 #define NS_INTERFACE_TABLE_END_WITH_PTR(_ptr)                       \
1124   { nullptr, 0 }                                                    \
1125   }                                                                 \
1126   ;                                                                 \
1127   static_assert(std::size(table) > 1, "need at least 1 interface"); \
1128   rv = NS_TableDrivenQI(static_cast<void*>(_ptr), aIID, aInstancePtr, table);
1129
1130 #define NS_INTERFACE_TABLE_END    \
1131   NS_INTERFACE_TABLE_END_WITH_PTR \
1132   (this)
1133
1134 #define NS_INTERFACE_TABLE_TAIL \
1135   return rv;                    \
1136   }
1137
1138 #define NS_INTERFACE_TABLE_TAIL_INHERITING(_baseclass)   \
1139   if (NS_SUCCEEDED(rv)) return rv;                       \
1140   return _baseclass::QueryInterface(aIID, aInstancePtr); \
1141   }
1142
1143 #define NS_INTERFACE_TABLE_TAIL_USING_AGGREGATOR(_aggregator) \
1144   if (NS_SUCCEEDED(rv)) return rv;                            \
1145   NS_ASSERTION(_aggregator, "null aggregator");               \
1146   return _aggregator->QueryInterface(aIID, aInstancePtr)      \
1147   }
1148
1149 /**
1150  * This implements query interface with two assumptions: First, the
1151  * class in question implements nsISupports and its own interface and
1152  * nothing else. Second, the implementation of the class's primary
1153  * inheritance chain leads to its own interface.
1154  *
1155  * @param _class The name of the class implementing the method
1156  * @param _classiiddef The name of the #define symbol that defines the IID
1157  * for the class (e.g. NS_ISUPPORTS_IID)
1158  */
1159
1160 #define NS_IMPL_QUERY_HEAD(_class)                                           \
1161   NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr) { \
1162     NS_ASSERTION(aInstancePtr,                                               \
1163                  "QueryInterface requires a non-NULL destination!");         \
1164     nsISupports* foundInterface;
1165
1166 #define NS_IMPL_QUERY_BODY_IID(_interface)                                   \
1167   mozilla::detail::kImplementedIID<std::remove_reference_t<decltype(*this)>, \
1168                                    _interface>
1169
1170 #define NS_IMPL_QUERY_BODY(_interface)                 \
1171   if (aIID.Equals(NS_IMPL_QUERY_BODY_IID(_interface))) \
1172     foundInterface = static_cast<_interface*>(this);   \
1173   else
1174
1175 #define NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)         \
1176   if ((condition) && aIID.Equals(NS_IMPL_QUERY_BODY_IID(_interface))) \
1177     foundInterface = static_cast<_interface*>(this);                  \
1178   else
1179
1180 #define NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)                   \
1181   if (aIID.Equals(NS_IMPL_QUERY_BODY_IID(_interface)))                         \
1182     foundInterface = static_cast<_interface*>(static_cast<_implClass*>(this)); \
1183   else
1184
1185 // Use this for querying to concrete class types which cannot be unambiguously
1186 // cast to nsISupports. See also nsQueryObject.h.
1187 #define NS_IMPL_QUERY_BODY_CONCRETE(_class)                       \
1188   if (aIID.Equals(NS_IMPL_QUERY_BODY_IID(_class))) {              \
1189     *aInstancePtr = do_AddRef(static_cast<_class*>(this)).take(); \
1190     return NS_OK;                                                 \
1191   } else
1192
1193 #define NS_IMPL_QUERY_BODY_AGGREGATED(_interface, _aggregate) \
1194   if (aIID.Equals(NS_IMPL_QUERY_BODY_IID(_interface)))        \
1195     foundInterface = static_cast<_interface*>(_aggregate);    \
1196   else
1197
1198 #define NS_IMPL_QUERY_TAIL_GUTS                                      \
1199   foundInterface = 0;                                                \
1200   nsresult status;                                                   \
1201   if (!foundInterface) {                                             \
1202     /* nsISupports should be handled by this point. If not, fail. */ \
1203     MOZ_ASSERT(!aIID.Equals(NS_GET_IID(nsISupports)));               \
1204     status = NS_NOINTERFACE;                                         \
1205   } else {                                                           \
1206     NS_ADDREF(foundInterface);                                       \
1207     status = NS_OK;                                                  \
1208   }                                                                  \
1209   *aInstancePtr = foundInterface;                                    \
1210   return status;                                                     \
1211   }
1212
1213 #define NS_IMPL_QUERY_TAIL_INHERITING(_baseclass)                       \
1214   foundInterface = 0;                                                   \
1215   nsresult status;                                                      \
1216   if (!foundInterface)                                                  \
1217     status = _baseclass::QueryInterface(aIID, (void**)&foundInterface); \
1218   else {                                                                \
1219     NS_ADDREF(foundInterface);                                          \
1220     status = NS_OK;                                                     \
1221   }                                                                     \
1222   *aInstancePtr = foundInterface;                                       \
1223   return status;                                                        \
1224   }
1225
1226 #define NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)                 \
1227   foundInterface = 0;                                                    \
1228   nsresult status;                                                       \
1229   if (!foundInterface) {                                                 \
1230     NS_ASSERTION(_aggregator, "null aggregator");                        \
1231     status = _aggregator->QueryInterface(aIID, (void**)&foundInterface); \
1232   } else {                                                               \
1233     NS_ADDREF(foundInterface);                                           \
1234     status = NS_OK;                                                      \
1235   }                                                                      \
1236   *aInstancePtr = foundInterface;                                        \
1237   return status;                                                         \
1238   }
1239
1240 #define NS_IMPL_QUERY_TAIL(_supports_interface)                  \
1241   NS_IMPL_QUERY_BODY_AMBIGUOUS(nsISupports, _supports_interface) \
1242   NS_IMPL_QUERY_TAIL_GUTS
1243
1244 /*
1245   This is the new scheme.  Using this notation now will allow us to switch to
1246   a table driven mechanism when it's ready.  Note the difference between this
1247   and the (currently) underlying NS_IMPL_QUERY_INTERFACE mechanism.  You must
1248   explicitly mention |nsISupports| when using the interface maps.
1249 */
1250 #define NS_INTERFACE_MAP_BEGIN(_implClass) NS_IMPL_QUERY_HEAD(_implClass)
1251 #define NS_INTERFACE_MAP_ENTRY(_interface) NS_IMPL_QUERY_BODY(_interface)
1252 #define NS_INTERFACE_MAP_ENTRY_CONDITIONAL(_interface, condition) \
1253   NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)
1254 #define NS_INTERFACE_MAP_ENTRY_AGGREGATED(_interface, _aggregate) \
1255   NS_IMPL_QUERY_BODY_AGGREGATED(_interface, _aggregate)
1256
1257 #define NS_INTERFACE_MAP_END NS_IMPL_QUERY_TAIL_GUTS
1258 #define NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(_interface, _implClass) \
1259   NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)
1260 #define NS_INTERFACE_MAP_ENTRY_CONCRETE(_class) \
1261   NS_IMPL_QUERY_BODY_CONCRETE(_class)
1262 #define NS_INTERFACE_MAP_END_INHERITING(_baseClass) \
1263   NS_IMPL_QUERY_TAIL_INHERITING(_baseClass)
1264 #define NS_INTERFACE_MAP_END_AGGREGATED(_aggregator) \
1265   NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)
1266
1267 #define NS_INTERFACE_TABLE0(_class)               \
1268   NS_INTERFACE_TABLE_BEGIN                        \
1269     NS_INTERFACE_TABLE_ENTRY(_class, nsISupports) \
1270   NS_INTERFACE_TABLE_END
1271
1272 #define NS_INTERFACE_TABLE(aClass, ...)                               \
1273   static_assert(MOZ_ARG_COUNT(__VA_ARGS__) > 0,                       \
1274                 "Need more arguments to NS_INTERFACE_TABLE");         \
1275   NS_INTERFACE_TABLE_BEGIN                                            \
1276     MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass, ), (__VA_ARGS__)) \
1277     NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(aClass, nsISupports,           \
1278                                        MOZ_ARG_1(__VA_ARGS__))        \
1279   NS_INTERFACE_TABLE_END
1280
1281 #define NS_IMPL_QUERY_INTERFACE0(_class) \
1282   NS_INTERFACE_TABLE_HEAD(_class)        \
1283     NS_INTERFACE_TABLE0(_class)          \
1284   NS_INTERFACE_TABLE_TAIL
1285
1286 #define NS_IMPL_QUERY_INTERFACE(aClass, ...) \
1287   NS_INTERFACE_TABLE_HEAD(aClass)            \
1288     NS_INTERFACE_TABLE(aClass, __VA_ARGS__)  \
1289   NS_INTERFACE_TABLE_TAIL
1290
1291 /**
1292  * Declare that you're going to inherit from something that already
1293  * implements nsISupports, but also implements an additional interface, thus
1294  * causing an ambiguity. In this case you don't need another mRefCnt, you
1295  * just need to forward the definitions to the appropriate superclass. E.g.
1296  *
1297  * class Bar : public Foo, public nsIBar {  // both provide nsISupports
1298  * public:
1299  *   NS_DECL_ISUPPORTS_INHERITED
1300  *   ...other nsIBar and Bar methods...
1301  * };
1302  */
1303 #define NS_DECL_ISUPPORTS_INHERITED                                       \
1304  public:                                                                  \
1305   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override; \
1306   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
1307   NS_IMETHOD_(MozExternalRefCountType) Release(void) override;
1308
1309 /**
1310  * These macros can be used in conjunction with NS_DECL_ISUPPORTS_INHERITED
1311  * to implement the nsISupports methods, forwarding the invocations to a
1312  * superclass that already implements nsISupports. Don't do anything for
1313  * subclasses of Runnable because it deals with subclass logging in its own
1314  * way, using the mName field.
1315  *
1316  * Note that I didn't make these inlined because they're virtual methods.
1317  */
1318
1319 namespace mozilla {
1320 class Runnable;
1321 namespace detail {
1322 class SupportsThreadSafeWeakPtrBase;
1323
1324 // Don't NS_LOG_{ADDREF,RELEASE} when inheriting from `Runnable*` or types with
1325 // thread safe weak references, as it will generate incorrect refcnt logs due to
1326 // the thread-safe `Upgrade()` call's refcount modifications not calling through
1327 // the derived class' `AddRef()` and `Release()` methods.
1328 template <typename T>
1329 constexpr bool ShouldLogInheritedRefcnt =
1330     !std::is_convertible_v<T*, Runnable*> &&
1331     !std::is_base_of_v<SupportsThreadSafeWeakPtrBase, T>;
1332 }
1333 }  // namespace mozilla
1334
1335 #define NS_IMPL_ADDREF_INHERITED_GUTS(Class, Super)                   \
1336   MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                           \
1337   nsrefcnt r = Super::AddRef();                                       \
1338   if constexpr (::mozilla::detail::ShouldLogInheritedRefcnt<Class>) { \
1339     NS_LOG_ADDREF(this, r, #Class, sizeof(*this));                    \
1340   }                                                                   \
1341   return r /* Purposefully no trailing semicolon */
1342
1343 #define NS_IMPL_ADDREF_INHERITED(Class, Super)                  \
1344   NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void) { \
1345     NS_IMPL_ADDREF_INHERITED_GUTS(Class, Super);                \
1346   }
1347
1348 #define NS_IMPL_RELEASE_INHERITED_GUTS(Class, Super)                  \
1349   nsrefcnt r = Super::Release();                                      \
1350   if constexpr (::mozilla::detail::ShouldLogInheritedRefcnt<Class>) { \
1351     NS_LOG_RELEASE(this, r, #Class);                                  \
1352   }                                                                   \
1353   return r /* Purposefully no trailing semicolon */
1354
1355 #define NS_IMPL_RELEASE_INHERITED(Class, Super)                  \
1356   NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void) { \
1357     NS_IMPL_RELEASE_INHERITED_GUTS(Class, Super);                \
1358   }
1359
1360 /**
1361  * As above but not logging the addref/release; needed if the base
1362  * class might be aggregated.
1363  */
1364 #define NS_IMPL_NONLOGGING_ADDREF_INHERITED(Class, Super)       \
1365   NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void) { \
1366     MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                   \
1367     return Super::AddRef();                                     \
1368   }
1369
1370 #define NS_IMPL_NONLOGGING_RELEASE_INHERITED(Class, Super)       \
1371   NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void) { \
1372     return Super::Release();                                     \
1373   }
1374
1375 #define NS_INTERFACE_TABLE_INHERITED0(Class) /* Nothing to do here */
1376
1377 #define NS_INTERFACE_TABLE_INHERITED(aClass, ...)                       \
1378   static_assert(MOZ_ARG_COUNT(__VA_ARGS__) > 0,                         \
1379                 "Need more arguments to NS_INTERFACE_TABLE_INHERITED"); \
1380   NS_INTERFACE_TABLE_BEGIN                                              \
1381     MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass, ), (__VA_ARGS__))   \
1382   NS_INTERFACE_TABLE_END
1383
1384 #define NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, ...) \
1385   NS_INTERFACE_TABLE_HEAD(aClass)                              \
1386     NS_INTERFACE_TABLE_INHERITED(aClass, __VA_ARGS__)          \
1387   NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)
1388
1389 /**
1390  * Convenience macros for implementing all nsISupports methods for
1391  * a simple class.
1392  * @param _class The name of the class implementing the method
1393  * @param _classiiddef The name of the #define symbol that defines the IID
1394  * for the class (e.g. NS_ISUPPORTS_IID)
1395  */
1396
1397 #define NS_IMPL_ISUPPORTS0(_class) \
1398   NS_IMPL_ADDREF(_class)           \
1399   NS_IMPL_RELEASE(_class)          \
1400   NS_IMPL_QUERY_INTERFACE0(_class)
1401
1402 #define NS_IMPL_ISUPPORTS(aClass, ...) \
1403   NS_IMPL_ADDREF(aClass)               \
1404   NS_IMPL_RELEASE(aClass)              \
1405   NS_IMPL_QUERY_INTERFACE(aClass, __VA_ARGS__)
1406
1407 // When possible, prefer NS_INLINE_DECL_REFCOUNTING_INHERITED to
1408 // NS_IMPL_ISUPPORTS_INHERITED0.
1409 #define NS_IMPL_ISUPPORTS_INHERITED0(aClass, aSuper) \
1410   NS_INTERFACE_TABLE_HEAD(aClass)                    \
1411   NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)         \
1412   NS_IMPL_ADDREF_INHERITED(aClass, aSuper)           \
1413   NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
1414
1415 #define NS_IMPL_ISUPPORTS_INHERITED(aClass, aSuper, ...)         \
1416   NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, __VA_ARGS__) \
1417   NS_IMPL_ADDREF_INHERITED(aClass, aSuper)                       \
1418   NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
1419
1420 /**
1421  * A macro to declare and implement inherited addref/release for a class which
1422  * doesn't have or need to override QueryInterface from its base class.
1423  *
1424  * Note: This macro always overrides the `AddRef` and `Release` methods,
1425  * including when refcount logging is disabled, meaning that it will implement
1426  * the `AddRef` or `Release` method from another virtual base class.
1427  */
1428 #define NS_INLINE_DECL_REFCOUNTING_INHERITED(Class, Super)  \
1429   NS_IMETHOD_(MozExternalRefCountType) AddRef() override {  \
1430     NS_IMPL_ADDREF_INHERITED_GUTS(Class, Super);            \
1431   }                                                         \
1432   NS_IMETHOD_(MozExternalRefCountType) Release() override { \
1433     NS_IMPL_RELEASE_INHERITED_GUTS(Class, Super);           \
1434   }
1435
1436 /*
1437  * Macro to glue together a QI that starts with an interface table
1438  * and segues into an interface map (e.g. it uses singleton classinfo
1439  * or tearoffs).
1440  */
1441 #define NS_INTERFACE_TABLE_TO_MAP_SEGUE \
1442   if (rv == NS_OK) return rv;           \
1443   nsISupports* foundInterface;
1444
1445 ///////////////////////////////////////////////////////////////////////////////
1446
1447 /**
1448  * Macro to generate nsIClassInfo methods for classes which do not have
1449  * corresponding nsIFactory implementations.
1450  */
1451 #define NS_IMPL_THREADSAFE_CI(_class)                          \
1452   NS_IMETHODIMP                                                \
1453   _class::GetInterfaces(nsTArray<nsIID>& _array) {             \
1454     return NS_CI_INTERFACE_GETTER_NAME(_class)(_array);        \
1455   }                                                            \
1456                                                                \
1457   NS_IMETHODIMP                                                \
1458   _class::GetScriptableHelper(nsIXPCScriptable** _retval) {    \
1459     *_retval = nullptr;                                        \
1460     return NS_OK;                                              \
1461   }                                                            \
1462                                                                \
1463   NS_IMETHODIMP                                                \
1464   _class::GetContractID(nsACString& _contractID) {             \
1465     _contractID.SetIsVoid(true);                               \
1466     return NS_OK;                                              \
1467   }                                                            \
1468                                                                \
1469   NS_IMETHODIMP                                                \
1470   _class::GetClassDescription(nsACString& _classDescription) { \
1471     _classDescription.SetIsVoid(true);                         \
1472     return NS_OK;                                              \
1473   }                                                            \
1474                                                                \
1475   NS_IMETHODIMP                                                \
1476   _class::GetClassID(nsCID** _classID) {                       \
1477     *_classID = nullptr;                                       \
1478     return NS_OK;                                              \
1479   }                                                            \
1480                                                                \
1481   NS_IMETHODIMP                                                \
1482   _class::GetFlags(uint32_t* _flags) {                         \
1483     *_flags = nsIClassInfo::THREADSAFE;                        \
1484     return NS_OK;                                              \
1485   }                                                            \
1486                                                                \
1487   NS_IMETHODIMP                                                \
1488   _class::GetClassIDNoAlloc(nsCID* _classIDNoAlloc) {          \
1489     return NS_ERROR_NOT_AVAILABLE;                             \
1490   }
1491
1492 #endif