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1 : // Protocol Buffers - Google's data interchange format
2 : // Copyright 2008 Google Inc. All rights reserved.
3 : // https://developers.google.com/protocol-buffers/
4 : //
5 : // Redistribution and use in source and binary forms, with or without
6 : // modification, are permitted provided that the following conditions are
7 : // met:
8 : //
9 : // * Redistributions of source code must retain the above copyright
10 : // notice, this list of conditions and the following disclaimer.
11 : // * Redistributions in binary form must reproduce the above
12 : // copyright notice, this list of conditions and the following disclaimer
13 : // in the documentation and/or other materials provided with the
14 : // distribution.
15 : // * Neither the name of Google Inc. nor the names of its
16 : // contributors may be used to endorse or promote products derived from
17 : // this software without specific prior written permission.
18 : //
19 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 :
31 : // This file defines an Arena allocator for better allocation performance.
32 :
33 : #ifndef GOOGLE_PROTOBUF_ARENA_H__
34 : #define GOOGLE_PROTOBUF_ARENA_H__
35 :
36 : #include <limits>
37 : #ifdef max
38 : #undef max // Visual Studio defines this macro
39 : #endif
40 : #if defined(_MSC_VER) && !defined(_LIBCPP_STD_VER) && !_HAS_EXCEPTIONS
41 : // Work around bugs in MSVC <typeinfo> header when _HAS_EXCEPTIONS=0.
42 : #include <exception>
43 : #include <typeinfo>
44 : namespace std {
45 : using type_info = ::type_info;
46 : }
47 : #else
48 : #include <typeinfo>
49 : #endif
50 :
51 : #include <google/protobuf/arena_impl.h>
52 : #include <google/protobuf/stubs/port.h>
53 : #include <type_traits>
54 :
55 : namespace google {
56 : namespace protobuf {
57 :
58 : struct ArenaOptions; // defined below
59 :
60 : } // namespace protobuf
61 :
62 : namespace quality_webanswers {
63 :
64 : void TempPrivateWorkAround(::google::protobuf::ArenaOptions* arena_options);
65 :
66 : } // namespace quality_webanswers
67 :
68 : namespace protobuf {
69 :
70 : class Arena; // defined below
71 : class Message; // defined in message.h
72 : class MessageLite;
73 :
74 : namespace arena_metrics {
75 :
76 : void EnableArenaMetrics(::google::protobuf::ArenaOptions* options);
77 :
78 : } // namespace arena_metrics
79 :
80 : namespace internal {
81 :
82 : struct ArenaStringPtr; // defined in arenastring.h
83 : class LazyField; // defined in lazy_field.h
84 :
85 : template <typename Type>
86 : class GenericTypeHandler; // defined in repeated_field.h
87 :
88 : // Templated cleanup methods.
89 : template <typename T>
90 0 : void arena_destruct_object(void* object) {
91 0 : reinterpret_cast<T*>(object)->~T();
92 0 : }
93 : template <typename T>
94 : void arena_delete_object(void* object) {
95 : delete reinterpret_cast<T*>(object);
96 : }
97 : inline void arena_free(void* object, size_t size) {
98 : #if defined(__GXX_DELETE_WITH_SIZE__) || defined(__cpp_sized_deallocation)
99 : ::operator delete(object, size);
100 : #else
101 : (void)size;
102 : ::operator delete(object);
103 : #endif
104 : }
105 :
106 : } // namespace internal
107 :
108 : // ArenaOptions provides optional additional parameters to arena construction
109 : // that control its block-allocation behavior.
110 : struct ArenaOptions {
111 : // This defines the size of the first block requested from the system malloc.
112 : // Subsequent block sizes will increase in a geometric series up to a maximum.
113 : size_t start_block_size;
114 :
115 : // This defines the maximum block size requested from system malloc (unless an
116 : // individual arena allocation request occurs with a size larger than this
117 : // maximum). Requested block sizes increase up to this value, then remain
118 : // here.
119 : size_t max_block_size;
120 :
121 : // An initial block of memory for the arena to use, or NULL for none. If
122 : // provided, the block must live at least as long as the arena itself. The
123 : // creator of the Arena retains ownership of the block after the Arena is
124 : // destroyed.
125 : char* initial_block;
126 :
127 : // The size of the initial block, if provided.
128 : size_t initial_block_size;
129 :
130 : // A function pointer to an alloc method that returns memory blocks of size
131 : // requested. By default, it contains a ptr to the malloc function.
132 : //
133 : // NOTE: block_alloc and dealloc functions are expected to behave like
134 : // malloc and free, including Asan poisoning.
135 : void* (*block_alloc)(size_t);
136 : // A function pointer to a dealloc method that takes ownership of the blocks
137 : // from the arena. By default, it contains a ptr to a wrapper function that
138 : // calls free.
139 : void (*block_dealloc)(void*, size_t);
140 :
141 : ArenaOptions()
142 : : start_block_size(kDefaultStartBlockSize),
143 : max_block_size(kDefaultMaxBlockSize),
144 : initial_block(NULL),
145 : initial_block_size(0),
146 : block_alloc(&::operator new),
147 : block_dealloc(&internal::arena_free),
148 : on_arena_init(NULL),
149 : on_arena_reset(NULL),
150 : on_arena_destruction(NULL),
151 : on_arena_allocation(NULL) {}
152 :
153 : private:
154 : // Hooks for adding external functionality such as user-specific metrics
155 : // collection, specific debugging abilities, etc.
156 : // Init hook may return a pointer to a cookie to be stored in the arena.
157 : // reset and destruction hooks will then be called with the same cookie
158 : // pointer. This allows us to save an external object per arena instance and
159 : // use it on the other hooks (Note: It is just as legal for init to return
160 : // NULL and not use the cookie feature).
161 : // on_arena_reset and on_arena_destruction also receive the space used in
162 : // the arena just before the reset.
163 : void* (*on_arena_init)(Arena* arena);
164 : void (*on_arena_reset)(Arena* arena, void* cookie, uint64 space_used);
165 : void (*on_arena_destruction)(Arena* arena, void* cookie, uint64 space_used);
166 :
167 : // type_info is promised to be static - its lifetime extends to
168 : // match program's lifetime (It is given by typeid operator).
169 : // Note: typeid(void) will be passed as allocated_type every time we
170 : // intentionally want to avoid monitoring an allocation. (i.e. internal
171 : // allocations for managing the arena)
172 : void (*on_arena_allocation)(const std::type_info* allocated_type,
173 : uint64 alloc_size, void* cookie);
174 :
175 : // Constants define default starting block size and max block size for
176 : // arena allocator behavior -- see descriptions above.
177 : static const size_t kDefaultStartBlockSize = 256;
178 : static const size_t kDefaultMaxBlockSize = 8192;
179 :
180 : friend void ::google::protobuf::arena_metrics::EnableArenaMetrics(ArenaOptions*);
181 : friend void quality_webanswers::TempPrivateWorkAround(ArenaOptions*);
182 : friend class Arena;
183 : friend class ArenaOptionsTestFriend;
184 : };
185 :
186 : // Support for non-RTTI environments. (The metrics hooks API uses type
187 : // information.)
188 : #ifndef GOOGLE_PROTOBUF_NO_RTTI
189 : #define RTTI_TYPE_ID(type) (&typeid(type))
190 : #else
191 : #define RTTI_TYPE_ID(type) (NULL)
192 : #endif
193 :
194 : // Arena allocator. Arena allocation replaces ordinary (heap-based) allocation
195 : // with new/delete, and improves performance by aggregating allocations into
196 : // larger blocks and freeing allocations all at once. Protocol messages are
197 : // allocated on an arena by using Arena::CreateMessage<T>(Arena*), below, and
198 : // are automatically freed when the arena is destroyed.
199 : //
200 : // This is a thread-safe implementation: multiple threads may allocate from the
201 : // arena concurrently. Destruction is not thread-safe and the destructing
202 : // thread must synchronize with users of the arena first.
203 : //
204 : // An arena provides two allocation interfaces: CreateMessage<T>, which works
205 : // for arena-enabled proto2 message types as well as other types that satisfy
206 : // the appropriate protocol (described below), and Create<T>, which works for
207 : // any arbitrary type T. CreateMessage<T> is better when the type T supports it,
208 : // because this interface (i) passes the arena pointer to the created object so
209 : // that its sub-objects and internal allocations can use the arena too, and (ii)
210 : // elides the object's destructor call when possible. Create<T> does not place
211 : // any special requirements on the type T, and will invoke the object's
212 : // destructor when the arena is destroyed.
213 : //
214 : // The arena message allocation protocol, required by CreateMessage<T>, is as
215 : // follows:
216 : //
217 : // - The type T must have (at least) two constructors: a constructor with no
218 : // arguments, called when a T is allocated on the heap; and a constructor with
219 : // a google::protobuf::Arena* argument, called when a T is allocated on an arena. If the
220 : // second constructor is called with a NULL arena pointer, it must be
221 : // equivalent to invoking the first (no-argument) constructor.
222 : //
223 : // - The type T must have a particular type trait: a nested type
224 : // |InternalArenaConstructable_|. This is usually a typedef to |void|. If no
225 : // such type trait exists, then the instantiation CreateMessage<T> will fail
226 : // to compile.
227 : //
228 : // - The type T *may* have the type trait |DestructorSkippable_|. If this type
229 : // trait is present in the type, then its destructor will not be called if and
230 : // only if it was passed a non-NULL arena pointer. If this type trait is not
231 : // present on the type, then its destructor is always called when the
232 : // containing arena is destroyed.
233 : //
234 : // - One- and two-user-argument forms of CreateMessage<T>() also exist that
235 : // forward these constructor arguments to T's constructor: for example,
236 : // CreateMessage<T>(Arena*, arg1, arg2) forwards to a constructor T(Arena*,
237 : // arg1, arg2).
238 : //
239 : // This protocol is implemented by all arena-enabled proto2 message classes as
240 : // well as RepeatedPtrField.
241 : //
242 : // Do NOT subclass Arena. This class will be marked as final when C++11 is
243 : // enabled.
244 : class LIBPROTOBUF_EXPORT Arena {
245 : public:
246 : // Arena constructor taking custom options. See ArenaOptions below for
247 : // descriptions of the options available.
248 : explicit Arena(const ArenaOptions& options) : impl_(options) {
249 : Init(options);
250 : }
251 :
252 : // Block overhead. Use this as a guide for how much to over-allocate the
253 : // initial block if you want an allocation of size N to fit inside it.
254 : //
255 : // WARNING: if you allocate multiple objects, it is difficult to guarantee
256 : // that a series of allocations will fit in the initial block, especially if
257 : // Arena changes its alignment guarantees in the future!
258 : static const size_t kBlockOverhead = internal::ArenaImpl::kBlockHeaderSize +
259 : internal::ArenaImpl::kSerialArenaSize;
260 :
261 : // Default constructor with sensible default options, tuned for average
262 : // use-cases.
263 : Arena() : impl_(ArenaOptions()) { Init(ArenaOptions()); }
264 :
265 : ~Arena() {
266 : if (hooks_cookie_) {
267 : CallDestructorHooks();
268 : }
269 : }
270 :
271 : void Init(const ArenaOptions& options) {
272 : on_arena_allocation_ = options.on_arena_allocation;
273 : on_arena_reset_ = options.on_arena_reset;
274 : on_arena_destruction_ = options.on_arena_destruction;
275 : // Call the initialization hook
276 : if (options.on_arena_init != NULL) {
277 : hooks_cookie_ = options.on_arena_init(this);
278 : } else {
279 : hooks_cookie_ = NULL;
280 : }
281 : }
282 :
283 : // API to create proto2 message objects on the arena. If the arena passed in
284 : // is NULL, then a heap allocated object is returned. Type T must be a message
285 : // defined in a .proto file with cc_enable_arenas set to true, otherwise a
286 : // compilation error will occur.
287 : //
288 : // RepeatedField and RepeatedPtrField may also be instantiated directly on an
289 : // arena with this method.
290 : //
291 : // This function also accepts any type T that satisfies the arena message
292 : // allocation protocol, documented above.
293 : template <typename T, typename... Args>
294 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateMessage(
295 : Arena* arena, Args&&... args) {
296 : static_assert(
297 : InternalHelper<T>::is_arena_constructable::value,
298 : "CreateMessage can only construct types that are ArenaConstructable");
299 : // We must delegate to CreateMaybeMessage() and NOT CreateMessageInternal()
300 : // because protobuf generated classes specialize CreateMaybeMessage() and we
301 : // need to use that specialization for code size reasons.
302 : return Arena::CreateMaybeMessage<T>(arena, std::forward<Args>(args)...);
303 : }
304 :
305 : // API to create any objects on the arena. Note that only the object will
306 : // be created on the arena; the underlying ptrs (in case of a proto2 message)
307 : // will be still heap allocated. Proto messages should usually be allocated
308 : // with CreateMessage<T>() instead.
309 : //
310 : // Note that even if T satisfies the arena message construction protocol
311 : // (InternalArenaConstructable_ trait and optional DestructorSkippable_
312 : // trait), as described above, this function does not follow the protocol;
313 : // instead, it treats T as a black-box type, just as if it did not have these
314 : // traits. Specifically, T's constructor arguments will always be only those
315 : // passed to Create<T>() -- no additional arena pointer is implicitly added.
316 : // Furthermore, the destructor will always be called at arena destruction time
317 : // (unless the destructor is trivial). Hence, from T's point of view, it is as
318 : // if the object were allocated on the heap (except that the underlying memory
319 : // is obtained from the arena).
320 : template <typename T, typename... Args>
321 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* Create(Arena* arena,
322 : Args&&... args) {
323 14304 : return CreateNoMessage<T>(arena, is_arena_constructable<T>(),
324 14432 : std::forward<Args>(args)...);
325 : }
326 :
327 : // Create an array of object type T on the arena *without* invoking the
328 : // constructor of T. If `arena` is null, then the return value should be freed
329 : // with `delete[] x;` (or `::operator delete[](x);`).
330 : // To ensure safe uses, this function checks at compile time
331 : // (when compiled as C++11) that T is trivially default-constructible and
332 : // trivially destructible.
333 : template <typename T>
334 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateArray(
335 : Arena* arena, size_t num_elements) {
336 : static_assert(std::is_pod<T>::value,
337 : "CreateArray requires a trivially constructible type");
338 : static_assert(std::is_trivially_destructible<T>::value,
339 : "CreateArray requires a trivially destructible type");
340 0 : GOOGLE_CHECK_LE(num_elements, std::numeric_limits<size_t>::max() / sizeof(T))
341 : << "Requested size is too large to fit into size_t.";
342 0 : if (arena == NULL) {
343 0 : return static_cast<T*>(::operator new[](num_elements * sizeof(T)));
344 : } else {
345 0 : return arena->CreateInternalRawArray<T>(num_elements);
346 : }
347 : }
348 :
349 : // Returns the total space allocated by the arena, which is the sum of the
350 : // sizes of the underlying blocks. This method is relatively fast; a counter
351 : // is kept as blocks are allocated.
352 : uint64 SpaceAllocated() const { return impl_.SpaceAllocated(); }
353 : // Returns the total space used by the arena. Similar to SpaceAllocated but
354 : // does not include free space and block overhead. The total space returned
355 : // may not include space used by other threads executing concurrently with
356 : // the call to this method.
357 : uint64 SpaceUsed() const { return impl_.SpaceUsed(); }
358 : // DEPRECATED. Please use SpaceAllocated() and SpaceUsed().
359 : //
360 : // Combines SpaceAllocated and SpaceUsed. Returns a pair of
361 : // <space_allocated, space_used>.
362 : PROTOBUF_RUNTIME_DEPRECATED("Please use SpaceAllocated() and SpaceUsed()")
363 : std::pair<uint64, uint64> SpaceAllocatedAndUsed() const {
364 : return std::make_pair(SpaceAllocated(), SpaceUsed());
365 : }
366 :
367 : // Frees all storage allocated by this arena after calling destructors
368 : // registered with OwnDestructor() and freeing objects registered with Own().
369 : // Any objects allocated on this arena are unusable after this call. It also
370 : // returns the total space used by the arena which is the sums of the sizes
371 : // of the allocated blocks. This method is not thread-safe.
372 : GOOGLE_PROTOBUF_ATTRIBUTE_NOINLINE uint64 Reset() {
373 : // Call the reset hook
374 : if (on_arena_reset_ != NULL) {
375 : on_arena_reset_(this, hooks_cookie_, impl_.SpaceAllocated());
376 : }
377 : return impl_.Reset();
378 : }
379 :
380 : // Adds |object| to a list of heap-allocated objects to be freed with |delete|
381 : // when the arena is destroyed or reset.
382 : template <typename T>
383 : GOOGLE_PROTOBUF_ATTRIBUTE_NOINLINE void Own(T* object) {
384 : OwnInternal(object, std::is_convertible<T*, Message*>());
385 : }
386 :
387 : // Adds |object| to a list of objects whose destructors will be manually
388 : // called when the arena is destroyed or reset. This differs from Own() in
389 : // that it does not free the underlying memory with |delete|; hence, it is
390 : // normally only used for objects that are placement-newed into
391 : // arena-allocated memory.
392 : template <typename T>
393 : GOOGLE_PROTOBUF_ATTRIBUTE_NOINLINE void OwnDestructor(T* object) {
394 : if (object != NULL) {
395 : impl_.AddCleanup(object, &internal::arena_destruct_object<T>);
396 : }
397 : }
398 :
399 : // Adds a custom member function on an object to the list of destructors that
400 : // will be manually called when the arena is destroyed or reset. This differs
401 : // from OwnDestructor() in that any member function may be specified, not only
402 : // the class destructor.
403 : GOOGLE_PROTOBUF_ATTRIBUTE_NOINLINE void OwnCustomDestructor(
404 : void* object, void (*destruct)(void*)) {
405 : impl_.AddCleanup(object, destruct);
406 : }
407 :
408 : // Retrieves the arena associated with |value| if |value| is an arena-capable
409 : // message, or NULL otherwise. This differs from value->GetArena() in that the
410 : // latter is a virtual call, while this method is a templated call that
411 : // resolves at compile-time.
412 : template <typename T>
413 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static Arena* GetArena(
414 : const T* value) {
415 : return GetArenaInternal(value, is_arena_constructable<T>());
416 : }
417 :
418 : template <typename T>
419 : class InternalHelper {
420 : template <typename U>
421 : static char DestructorSkippable(const typename U::DestructorSkippable_*);
422 : template <typename U>
423 : static double DestructorSkippable(...);
424 :
425 : typedef std::integral_constant<
426 : bool, sizeof(DestructorSkippable<T>(static_cast<const T*>(0))) ==
427 : sizeof(char) ||
428 : std::is_trivially_destructible<T>::value>
429 : is_destructor_skippable;
430 :
431 : template <typename U>
432 : static char ArenaConstructable(
433 : const typename U::InternalArenaConstructable_*);
434 : template <typename U>
435 : static double ArenaConstructable(...);
436 :
437 : typedef std::integral_constant<bool, sizeof(ArenaConstructable<T>(
438 : static_cast<const T*>(0))) ==
439 : sizeof(char)>
440 : is_arena_constructable;
441 :
442 : template <typename... Args>
443 : static T* Construct(void* ptr, Args&&... args) {
444 : return new (ptr) T(std::forward<Args>(args)...);
445 : }
446 :
447 : static Arena* GetArena(const T* p) { return p->GetArenaNoVirtual(); }
448 :
449 : friend class Arena;
450 : };
451 :
452 : // Helper typetraits that indicates support for arenas in a type T at compile
453 : // time. This is public only to allow construction of higher-level templated
454 : // utilities.
455 : //
456 : // is_arena_constructable<T>::value is true if the message type T has arena
457 : // support enabled, and false otherwise.
458 : //
459 : // is_destructor_skippable<T>::value is true if the message type T has told
460 : // the arena that it is safe to skip the destructor, and false otherwise.
461 : //
462 : // This is inside Arena because only Arena has the friend relationships
463 : // necessary to see the underlying generated code traits.
464 : template <typename T>
465 : struct is_arena_constructable : InternalHelper<T>::is_arena_constructable {};
466 : template <typename T>
467 : struct is_destructor_skippable : InternalHelper<T>::is_destructor_skippable {
468 : };
469 :
470 : private:
471 : template <typename T, typename... Args>
472 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateMessageInternal(
473 : Arena* arena, Args&&... args) {
474 : static_assert(
475 : InternalHelper<T>::is_arena_constructable::value,
476 : "CreateMessage can only construct types that are ArenaConstructable");
477 : if (arena == NULL) {
478 : return new T(nullptr, std::forward<Args>(args)...);
479 : } else {
480 : return arena->DoCreateMessage<T>(std::forward<Args>(args)...);
481 : }
482 : }
483 :
484 : // This specialization for no arguments is necessary, because its behavior is
485 : // slightly different. When the arena pointer is nullptr, it calls T()
486 : // instead of T(nullptr).
487 : template <typename T>
488 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateMessageInternal(
489 : Arena* arena) {
490 : static_assert(
491 : InternalHelper<T>::is_arena_constructable::value,
492 : "CreateMessage can only construct types that are ArenaConstructable");
493 : if (arena == NULL) {
494 : return new T();
495 : } else {
496 : return arena->DoCreateMessage<T>();
497 : }
498 : }
499 :
500 : template <typename T, typename... Args>
501 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateInternal(
502 : Arena* arena, Args&&... args) {
503 7216 : if (arena == NULL) {
504 7216 : return new T(std::forward<Args>(args)...);
505 : } else {
506 0 : return arena->DoCreate<T>(std::is_trivially_destructible<T>::value,
507 0 : std::forward<Args>(args)...);
508 : }
509 : }
510 :
511 : void CallDestructorHooks();
512 : void OnArenaAllocation(const std::type_info* allocated_type, size_t n) const;
513 0 : inline void AllocHook(const std::type_info* allocated_type, size_t n) const {
514 0 : if (GOOGLE_PREDICT_FALSE(hooks_cookie_ != NULL)) {
515 0 : OnArenaAllocation(allocated_type, n);
516 : }
517 0 : }
518 :
519 : // Allocate and also optionally call on_arena_allocation callback with the
520 : // allocated type info when the hooks are in place in ArenaOptions and
521 : // the cookie is not null.
522 : template <typename T>
523 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE void* AllocateInternal(
524 : bool skip_explicit_ownership) {
525 0 : const size_t n = internal::AlignUpTo8(sizeof(T));
526 0 : AllocHook(RTTI_TYPE_ID(T), n);
527 : // Monitor allocation if needed.
528 0 : if (skip_explicit_ownership) {
529 0 : return impl_.AllocateAligned(n);
530 : } else {
531 0 : return impl_.AllocateAlignedAndAddCleanup(
532 0 : n, &internal::arena_destruct_object<T>);
533 : }
534 : }
535 :
536 : // CreateMessage<T> requires that T supports arenas, but this private method
537 : // works whether or not T supports arenas. These are not exposed to user code
538 : // as it can cause confusing API usages, and end up having double free in
539 : // user code. These are used only internally from LazyField and Repeated
540 : // fields, since they are designed to work in all mode combinations.
541 : template <typename Msg, typename... Args>
542 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static Msg* DoCreateMaybeMessage(
543 : Arena* arena, std::true_type, Args&&... args) {
544 : return CreateMessageInternal<Msg>(arena, std::forward<Args>(args)...);
545 : }
546 :
547 : template <typename T, typename... Args>
548 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* DoCreateMaybeMessage(
549 : Arena* arena, std::false_type, Args&&... args) {
550 7216 : return CreateInternal<T>(arena, std::forward<Args>(args)...);
551 : }
552 :
553 : template <typename T, typename... Args>
554 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateMaybeMessage(
555 : Arena* arena, Args&&... args) {
556 14432 : return DoCreateMaybeMessage<T>(arena, is_arena_constructable<T>(),
557 14432 : std::forward<Args>(args)...);
558 : }
559 :
560 : template <typename T, typename... Args>
561 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateNoMessage(
562 : Arena* arena, std::true_type, Args&&... args) {
563 : // User is constructing with Create() despite the fact that T supports arena
564 : // construction. In this case we have to delegate to CreateInternal(), and
565 : // we can't use any CreateMaybeMessage() specialization that may be defined.
566 : return CreateInternal<T>(arena, std::forward<Args>(args)...);
567 : }
568 :
569 : template <typename T, typename... Args>
570 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static T* CreateNoMessage(
571 : Arena* arena, std::false_type, Args&&... args) {
572 : // User is constructing with Create() and the type does not support arena
573 : // construction. In this case we can delegate to CreateMaybeMessage() and
574 : // use any specialization that may be available for that.
575 14304 : return CreateMaybeMessage<T>(arena, std::forward<Args>(args)...);
576 : }
577 :
578 : // Just allocate the required size for the given type assuming the
579 : // type has a trivial constructor.
580 : template <typename T>
581 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE T* CreateInternalRawArray(
582 : size_t num_elements) {
583 0 : GOOGLE_CHECK_LE(num_elements, std::numeric_limits<size_t>::max() / sizeof(T))
584 : << "Requested size is too large to fit into size_t.";
585 0 : const size_t n = internal::AlignUpTo8(sizeof(T) * num_elements);
586 : // Monitor allocation if needed.
587 0 : AllocHook(RTTI_TYPE_ID(T), n);
588 0 : return static_cast<T*>(impl_.AllocateAligned(n));
589 : }
590 :
591 : template <typename T, typename... Args>
592 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE T* DoCreate(
593 : bool skip_explicit_ownership, Args&&... args) {
594 0 : return new (AllocateInternal<T>(skip_explicit_ownership))
595 0 : T(std::forward<Args>(args)...);
596 : }
597 : template <typename T, typename... Args>
598 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE T* DoCreateMessage(Args&&... args) {
599 : return InternalHelper<T>::Construct(
600 : AllocateInternal<T>(InternalHelper<T>::is_destructor_skippable::value),
601 : this, std::forward<Args>(args)...);
602 : }
603 :
604 : // CreateInArenaStorage is used to implement map field. Without it,
605 : // google::protobuf::Map need to call generated message's protected arena constructor,
606 : // which needs to declare google::protobuf::Map as friend of generated message.
607 : template <typename T>
608 : static void CreateInArenaStorage(T* ptr, Arena* arena) {
609 : CreateInArenaStorageInternal(ptr, arena,
610 : typename is_arena_constructable<T>::type());
611 : RegisterDestructorInternal(
612 : ptr, arena,
613 : typename InternalHelper<T>::is_destructor_skippable::type());
614 : }
615 :
616 : template <typename T>
617 : static void CreateInArenaStorageInternal(T* ptr, Arena* arena,
618 : std::true_type) {
619 : InternalHelper<T>::Construct(ptr, arena);
620 : }
621 : template <typename T>
622 : static void CreateInArenaStorageInternal(T* ptr, Arena* /* arena */,
623 : std::false_type) {
624 : new (ptr) T();
625 : }
626 :
627 : template <typename T>
628 : static void RegisterDestructorInternal(T* /* ptr */, Arena* /* arena */,
629 : std::true_type) {}
630 : template <typename T>
631 : static void RegisterDestructorInternal(T* ptr, Arena* arena,
632 : std::false_type) {
633 : arena->OwnDestructor(ptr);
634 : }
635 :
636 : // These implement Own(), which registers an object for deletion (destructor
637 : // call and operator delete()). The second parameter has type 'true_type' if T
638 : // is a subtype of ::google::protobuf::Message and 'false_type' otherwise. Collapsing
639 : // all template instantiations to one for generic Message reduces code size,
640 : // using the virtual destructor instead.
641 : template <typename T>
642 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE void OwnInternal(T* object,
643 : std::true_type) {
644 : if (object != NULL) {
645 : impl_.AddCleanup(object, &internal::arena_delete_object<Message>);
646 : }
647 : }
648 : template <typename T>
649 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE void OwnInternal(T* object,
650 : std::false_type) {
651 : if (object != NULL) {
652 : impl_.AddCleanup(object, &internal::arena_delete_object<T>);
653 : }
654 : }
655 :
656 : // Implementation for GetArena(). Only message objects with
657 : // InternalArenaConstructable_ tags can be associated with an arena, and such
658 : // objects must implement a GetArenaNoVirtual() method.
659 : template <typename T>
660 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static Arena* GetArenaInternal(
661 : const T* value, std::true_type) {
662 : return InternalHelper<T>::GetArena(value);
663 : }
664 :
665 : template <typename T>
666 : GOOGLE_PROTOBUF_ATTRIBUTE_ALWAYS_INLINE static Arena* GetArenaInternal(
667 : const T* /* value */, std::false_type) {
668 : return NULL;
669 : }
670 :
671 : // For friends of arena.
672 : void* AllocateAligned(size_t n) {
673 : AllocHook(NULL, n);
674 : return impl_.AllocateAligned(internal::AlignUpTo8(n));
675 : }
676 :
677 : internal::ArenaImpl impl_;
678 :
679 : void (*on_arena_allocation_)(const std::type_info* allocated_type,
680 : uint64 alloc_size, void* cookie);
681 : void (*on_arena_reset_)(Arena* arena, void* cookie, uint64 space_used);
682 : void (*on_arena_destruction_)(Arena* arena, void* cookie, uint64 space_used);
683 :
684 : // The arena may save a cookie it receives from the external on_init hook
685 : // and then use it when calling the on_reset and on_destruction hooks.
686 : void* hooks_cookie_;
687 :
688 : template <typename Type>
689 : friend class internal::GenericTypeHandler;
690 : friend struct internal::ArenaStringPtr; // For AllocateAligned.
691 : friend class internal::LazyField; // For CreateMaybeMessage.
692 : friend class MessageLite;
693 : template <typename Key, typename T>
694 : friend class Map;
695 : };
696 :
697 : // Defined above for supporting environments without RTTI.
698 : #undef RTTI_TYPE_ID
699 :
700 : } // namespace protobuf
701 :
702 : } // namespace google
703 : #endif // GOOGLE_PROTOBUF_ARENA_H__
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