diff options
Diffstat (limited to 'src/google/protobuf/repeated_field.h')
| -rw-r--r-- | src/google/protobuf/repeated_field.h | 151 |
1 files changed, 116 insertions, 35 deletions
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h index 5530fefe..1961bc48 100644 --- a/src/google/protobuf/repeated_field.h +++ b/src/google/protobuf/repeated_field.h @@ -208,10 +208,19 @@ class RepeatedField { // sizeof(*this) int SpaceUsedExcludingSelf() const; - // Remove the element referenced by position. + // Removes the element referenced by position. + // + // Returns an iterator to the element immediately following the removed + // element. + // + // Invalidates all iterators at or after the removed element, including end(). iterator erase(const_iterator position); - // Remove the elements in the range [first, last). + // Removes the elements in the range [first, last). + // + // Returns an iterator to the element immediately following the removed range. + // + // Invalidates all iterators at or after the removed range, including end(). iterator erase(const_iterator first, const_iterator last); // Get the Arena on which this RepeatedField stores its elements. @@ -235,7 +244,7 @@ class RepeatedField { int total_size_; struct Rep { Arena* arena; - Element elements[1]; + Element elements[1]; }; // We can not use sizeof(Rep) - sizeof(Element) due to the trailing padding on // the struct. We can not use sizeof(Arena*) as well because there might be @@ -263,6 +272,22 @@ class RepeatedField { inline Arena* GetArenaNoVirtual() const { return (rep_ == NULL) ? NULL : rep_->arena; } + + // Internal helper to delete all elements and deallocate the storage. + // If Element has a trivial destructor (for example, if it's a fundamental + // type, like int32), the loop will be removed by the optimizer. + void InternalDeallocate(Rep* rep, int size) { + if (rep != NULL) { + Element* e = &rep->elements[0]; + Element* limit = &rep->elements[size]; + for (; e < limit; e++) { + e->Element::~Element(); + } + if (rep->arena == NULL) { + delete[] reinterpret_cast<char*>(rep); + } + } + } }; template<typename Element> @@ -565,7 +590,7 @@ class GenericTypeHandler { template <typename GenericType> GenericType* GenericTypeHandler<GenericType>::NewFromPrototype( - const GenericType* prototype, ::google::protobuf::Arena* arena) { + const GenericType* /* prototype */, ::google::protobuf::Arena* arena) { return New(arena); } template <typename GenericType> @@ -601,6 +626,13 @@ inline void* GenericTypeHandler<MessageLite>::GetMaybeArenaPointer( template <> void GenericTypeHandler<MessageLite>::Merge(const MessageLite& from, MessageLite* to); +template<> +inline void GenericTypeHandler<string>::Clear(string* value) { + value->clear(); +} +template<> +void GenericTypeHandler<string>::Merge(const string& from, + string* to); // Declarations of the specialization as we cannot define them here, as the // header that defines ProtocolMessage depends on types defined in this header. @@ -618,7 +650,7 @@ void GenericTypeHandler<MessageLite>::Merge(const MessageLite& from, // Message specialization bodies defined in message.cc. This split is necessary // to allow proto2-lite (which includes this header) to be independent of // Message. -DECLARE_SPECIALIZATIONS_FOR_BASE_PROTO_TYPES(Message); +DECLARE_SPECIALIZATIONS_FOR_BASE_PROTO_TYPES(Message) #undef DECLARE_SPECIALIZATIONS_FOR_BASE_PROTO_TYPES @@ -665,7 +697,7 @@ class LIBPROTOBUF_EXPORT StringTypeHandlerBase { static inline ::google::protobuf::Arena* GetArena(string*) { return NULL; } - static inline void* GetMaybeArenaPointer(string* value) { + static inline void* GetMaybeArenaPointer(string* /* value */) { return NULL; } static inline void Delete(string* value, Arena* arena) { @@ -683,7 +715,7 @@ class LIBPROTOBUF_EXPORT StringTypeHandlerBase { class StringTypeHandler : public StringTypeHandlerBase { public: static int SpaceUsed(const string& value) { - return sizeof(value) + StringSpaceUsedExcludingSelf(value); + return static_cast<int>(sizeof(value)) + StringSpaceUsedExcludingSelf(value); } }; @@ -827,6 +859,15 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase { // Add an already-allocated object, skipping arena-ownership checks. The user // must guarantee that the given object is in the same arena as this // RepeatedPtrField. + // It is also useful in legacy code that uses temporary ownership to avoid + // copies. Example: + // RepeatedPtrField<T> temp_field; + // temp_field.AddAllocated(new T); + // ... // Do something with temp_field + // temp_field.ExtractSubrange(0, temp_field.size(), NULL); + // If you put temp_field on the arena this fails, because the ownership + // transfers to the arena at the "AddAllocated" call and is not released + // anymore causing a double delete. UnsafeArenaAddAllocated prevents this. void UnsafeArenaAddAllocated(Element* value); // Remove the last element and return it. Works only when operating on an @@ -885,10 +926,19 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase { // so will trigger a GOOGLE_DCHECK-failure. Element* ReleaseCleared(); - // Remove the element referenced by position. + // Removes the element referenced by position. + // + // Returns an iterator to the element immediately following the removed + // element. + // + // Invalidates all iterators at or after the removed element, including end(). iterator erase(const_iterator position); // Removes the elements in the range [first, last). + // + // Returns an iterator to the element immediately following the removed range. + // + // Invalidates all iterators at or after the removed range, including end(). iterator erase(const_iterator first, const_iterator last); // Gets the arena on which this RepeatedPtrField stores its elements. @@ -974,19 +1024,8 @@ RepeatedField<Element>::RepeatedField(Iter begin, const Iter& end) template <typename Element> RepeatedField<Element>::~RepeatedField() { // See explanation in Reserve(): we need to invoke destructors here for the - // case that Element has a non-trivial destructor. If Element has a trivial - // destructor (for example, if it's a primitive type, like int32), this entire - // loop will be removed by the optimizer. - if (rep_ != NULL) { - Element* e = &rep_->elements[0]; - Element* limit = &rep_->elements[total_size_]; - for (; e < limit; e++) { - e->Element::~Element(); - } - if (rep_->arena == NULL) { - delete[] reinterpret_cast<char*>(rep_); - } - } + // case that Element has a non-trivial destructor. + InternalDeallocate(rep_, total_size_); } template <typename Element> @@ -1222,8 +1261,8 @@ void RepeatedField<Element>::Reserve(int new_size) { if (total_size_ >= new_size) return; Rep* old_rep = rep_; Arena* arena = GetArenaNoVirtual(); - new_size = max(google::protobuf::internal::kMinRepeatedFieldAllocationSize, - max(total_size_ * 2, new_size)); + new_size = std::max(google::protobuf::internal::kMinRepeatedFieldAllocationSize, + std::max(total_size_ * 2, new_size)); GOOGLE_CHECK_LE(static_cast<size_t>(new_size), (std::numeric_limits<size_t>::max() - kRepHeaderSize) / sizeof(Element)) @@ -1256,18 +1295,10 @@ void RepeatedField<Element>::Reserve(int new_size) { if (current_size_ > 0) { MoveArray(rep_->elements, old_rep->elements, current_size_); } - if (old_rep) { - // Likewise, we need to invoke destructors on the old array. If Element has - // no destructor, this loop will disappear. - e = &old_rep->elements[0]; - limit = &old_rep->elements[old_total_size]; - for (; e < limit; e++) { - e->Element::~Element(); - } - if (arena == NULL) { - delete[] reinterpret_cast<char*>(old_rep); - } - } + + // Likewise, we need to invoke destructors on the old array. + InternalDeallocate(old_rep, old_total_size); + } template <typename Element> @@ -2362,6 +2393,37 @@ template<typename T> class AllocatedRepeatedPtrFieldBackInsertIterator private: RepeatedPtrField<T>* field_; }; + +// Almost identical to AllocatedRepeatedPtrFieldBackInsertIterator. This one +// uses the UnsafeArenaAddAllocated instead. +template<typename T> +class UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator + : public std::iterator<std::output_iterator_tag, T> { + public: + explicit UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator( + ::google::protobuf::RepeatedPtrField<T>* const mutable_field) + : field_(mutable_field) { + } + UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T>& operator=( + T const* const ptr_to_value) { + field_->UnsafeArenaAddAllocated(const_cast<T*>(ptr_to_value)); + return *this; + } + UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T>& operator*() { + return *this; + } + UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T>& operator++() { + return *this; + } + UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T>& operator++( + int /* unused */) { + return *this; + } + + private: + ::google::protobuf::RepeatedPtrField<T>* field_; +}; + } // namespace internal // Provides a back insert iterator for RepeatedField instances, @@ -2396,6 +2458,25 @@ AllocatedRepeatedPtrFieldBackInserter( mutable_field); } +// Similar to AllocatedRepeatedPtrFieldBackInserter, using +// UnsafeArenaAddAllocated instead of AddAllocated. +// This is slightly faster if that matters. It is also useful in legacy code +// that uses temporary ownership to avoid copies. Example: +// RepeatedPtrField<T> temp_field; +// temp_field.AddAllocated(new T); +// ... // Do something with temp_field +// temp_field.ExtractSubrange(0, temp_field.size(), NULL); +// If you put temp_field on the arena this fails, because the ownership +// transfers to the arena at the "AddAllocated" call and is not released anymore +// causing a double delete. Using UnsafeArenaAddAllocated prevents this. +template<typename T> +internal::UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T> +UnsafeArenaAllocatedRepeatedPtrFieldBackInserter( + ::google::protobuf::RepeatedPtrField<T>* const mutable_field) { + return internal::UnsafeArenaAllocatedRepeatedPtrFieldBackInsertIterator<T>( + mutable_field); +} + } // namespace protobuf } // namespace google |