diff options
Diffstat (limited to 'NorthstarDedicatedTest/include/protobuf/arenastring.h')
| -rw-r--r-- | NorthstarDedicatedTest/include/protobuf/arenastring.h | 420 |
1 files changed, 420 insertions, 0 deletions
diff --git a/NorthstarDedicatedTest/include/protobuf/arenastring.h b/NorthstarDedicatedTest/include/protobuf/arenastring.h new file mode 100644 index 00000000..573cd4a4 --- /dev/null +++ b/NorthstarDedicatedTest/include/protobuf/arenastring.h @@ -0,0 +1,420 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#ifndef GOOGLE_PROTOBUF_ARENASTRING_H__ +#define GOOGLE_PROTOBUF_ARENASTRING_H__ + +#include <string> +#include <type_traits> +#include <utility> + +#include <stubs/logging.h> +#include <stubs/common.h> +#include <arena.h> +#include <port.h> + +#include <port_def.inc> + +#ifdef SWIG +#error "You cannot SWIG proto headers" +#endif + + +namespace google { +namespace protobuf { +namespace internal { + +template <typename T> +class ExplicitlyConstructed; + +class SwapFieldHelper; + +// Lazy string instance to support string fields with non-empty default. +// These are initialized on the first call to .get(). +class PROTOBUF_EXPORT LazyString { + public: + // We explicitly make LazyString an aggregate so that MSVC can do constant + // initialization on it without marking it `constexpr`. + // We do not want to use `constexpr` because it makes it harder to have extern + // storage for it and causes library bloat. + struct InitValue { + const char* ptr; + size_t size; + }; + // We keep a union of the initialization value and the std::string to save on + // space. We don't need the string array after Init() is done. + union { + mutable InitValue init_value_; + alignas(std::string) mutable char string_buf_[sizeof(std::string)]; + }; + mutable std::atomic<const std::string*> inited_; + + const std::string& get() const { + // This check generates less code than a call-once invocation. + auto* res = inited_.load(std::memory_order_acquire); + if (PROTOBUF_PREDICT_FALSE(res == nullptr)) return Init(); + return *res; + } + + private: + // Initialize the string in `string_buf_`, update `inited_` and return it. + // We return it here to avoid having to read it again in the inlined code. + const std::string& Init() const; +}; + +template <typename T> +class TaggedPtr { + public: + TaggedPtr() = default; + explicit constexpr TaggedPtr(const ExplicitlyConstructed<std::string>* ptr) + : ptr_(const_cast<ExplicitlyConstructed<std::string>*>(ptr)) {} + + void SetTagged(T* p) { + Set(p); + ptr_ = reinterpret_cast<void*>(as_int() | 1); + } + void Set(T* p) { ptr_ = p; } + T* Get() const { return reinterpret_cast<T*>(as_int() & -2); } + bool IsTagged() const { return as_int() & 1; } + + // Returned value is only safe to dereference if IsTagged() == false. + // It is safe to compare. + T* UnsafeGet() const { return static_cast<T*>(ptr_); } + + bool IsNull() { return ptr_ == nullptr; } + + private: + uintptr_t as_int() const { return reinterpret_cast<uintptr_t>(ptr_); } + void* ptr_; +}; + +static_assert(std::is_trivial<TaggedPtr<std::string>>::value, + "TaggedPtr must be trivial"); + +// This class encapsulates a pointer to a std::string with or without a donated +// buffer, tagged by bottom bit. It is a high-level wrapper that almost directly +// corresponds to the interface required by string fields in generated +// code. It replaces the old std::string* pointer in such cases. +// +// The object has different but similar code paths for when the default value is +// the empty string and when it is a non-empty string. +// The empty string is handled different throughout the library and there is a +// single global instance of it we can share. +// +// For fields with an empty string default value, there are three distinct +// states: +// +// - Pointer set to 'String' tag (LSB is 0), equal to +// &GetEmptyStringAlreadyInited(): field is set to its default value. Points +// to a true std::string*, but we do not own that std::string* (it's a +// globally shared instance). +// +// - Pointer set to 'String' tag (LSB is 0), but not equal to the global empty +// string: field points to a true std::string* instance that we own. This +// instance is either on the heap or on the arena (i.e. registered on +// free()/destructor-call list) as appropriate. +// +// - Pointer set to 'DonatedString' tag (LSB is 1): points to a std::string +// instance with a buffer on the arena (arena is never nullptr in this case). +// +// For fields with a non-empty string default value, there are three distinct +// states: +// +// - Pointer set to 'String' tag (LSB is 0), equal to `nullptr`: +// Field is in "default" mode and does not point to any actual instance. +// Methods that might need to create an instance of the object will pass a +// `const LazyString&` for it. +// +// - Pointer set to 'String' tag (LSB is 0), but not equal to `nullptr`: +// field points to a true std::string* instance that we own. This instance is +// either on the heap or on the arena (i.e. registered on +// free()/destructor-call list) as appropriate. +// +// - Pointer set to 'DonatedString' tag (LSB is 1): points to a std::string +// instance with a buffer on the arena (arena is never nullptr in this case). +// +// Generated code and reflection code both ensure that ptr_ is never null for +// fields with an empty default. +// Because ArenaStringPtr is used in oneof unions, its constructor is a NOP and +// so the field is always manually initialized via method calls. +// +// Side-note: why pass information about the default on every API call? Because +// we don't want to hold it in a member variable, or else this would go into +// every proto message instance. This would be a huge waste of space, since the +// default instance pointer is typically a global (static class field). We want +// the generated code to be as efficient as possible, and if we take +// the default value information as a parameter that's in practice taken from a +// static class field, and compare ptr_ to the default value, we end up with a +// single "cmp %reg, GLOBAL" in the resulting machine code. (Note that this also +// requires the String tag to be 0 so we can avoid the mask before comparing.) +struct PROTOBUF_EXPORT ArenaStringPtr { + ArenaStringPtr() = default; + explicit constexpr ArenaStringPtr( + const ExplicitlyConstructed<std::string>* default_value) + : tagged_ptr_(default_value) {} + + // Some methods below are overloaded on a `default_value` and on tags. + // The tagged overloads help reduce code size in the callers in generated + // code, while the `default_value` overloads are useful from reflection. + // By-value empty struct arguments are elided in the ABI. + struct EmptyDefault {}; + struct NonEmptyDefault {}; + + void Set(const std::string* default_value, ConstStringParam value, + ::google::protobuf::Arena* arena); + void Set(const std::string* default_value, std::string&& value, + ::google::protobuf::Arena* arena); + void Set(EmptyDefault, ConstStringParam value, ::google::protobuf::Arena* arena); + void Set(EmptyDefault, std::string&& value, ::google::protobuf::Arena* arena); + void Set(NonEmptyDefault, ConstStringParam value, ::google::protobuf::Arena* arena); + void Set(NonEmptyDefault, std::string&& value, ::google::protobuf::Arena* arena); + template <typename FirstParam> + void Set(FirstParam p1, const char* str, ::google::protobuf::Arena* arena) { + Set(p1, ConstStringParam(str), arena); + } + template <typename FirstParam> + void Set(FirstParam p1, const char* str, size_t size, + ::google::protobuf::Arena* arena) { + ConstStringParam sp{str, size}; // for string_view and `const string &` + Set(p1, sp, arena); + } + template <typename FirstParam, typename RefWrappedType> + void Set(FirstParam p1, + std::reference_wrapper<RefWrappedType> const_string_ref, + ::google::protobuf::Arena* arena) { + Set(p1, const_string_ref.get(), arena); + } + + template <typename FirstParam, typename SecondParam> + void SetBytes(FirstParam p1, SecondParam&& p2, ::google::protobuf::Arena* arena) { + Set(p1, static_cast<SecondParam&&>(p2), arena); + } + template <typename FirstParam> + void SetBytes(FirstParam p1, const void* str, size_t size, + ::google::protobuf::Arena* arena) { + // must work whether ConstStringParam is string_view or `const string &` + ConstStringParam sp{static_cast<const char*>(str), size}; + Set(p1, sp, arena); + } + + // Basic accessors. + PROTOBUF_NDEBUG_INLINE const std::string& Get() const { + // Unconditionally mask away the tag. + return *tagged_ptr_.Get(); + } + PROTOBUF_NDEBUG_INLINE const std::string* GetPointer() const { + // Unconditionally mask away the tag. + return tagged_ptr_.Get(); + } + + // For fields with an empty default value. + std::string* Mutable(EmptyDefault, ::google::protobuf::Arena* arena); + // For fields with a non-empty default value. + std::string* Mutable(const LazyString& default_value, ::google::protobuf::Arena* arena); + + // Release returns a std::string* instance that is heap-allocated and is not + // Own()'d by any arena. If the field is not set, this returns nullptr. The + // caller retains ownership. Clears this field back to nullptr state. Used to + // implement release_<field>() methods on generated classes. + PROTOBUF_NODISCARD std::string* Release(const std::string* default_value, + ::google::protobuf::Arena* arena); + PROTOBUF_NODISCARD std::string* ReleaseNonDefault( + const std::string* default_value, ::google::protobuf::Arena* arena); + + // Takes a std::string that is heap-allocated, and takes ownership. The + // std::string's destructor is registered with the arena. Used to implement + // set_allocated_<field> in generated classes. + void SetAllocated(const std::string* default_value, std::string* value, + ::google::protobuf::Arena* arena); + + // Swaps internal pointers. Arena-safety semantics: this is guarded by the + // logic in Swap()/UnsafeArenaSwap() at the message level, so this method is + // 'unsafe' if called directly. + inline PROTOBUF_NDEBUG_INLINE static void InternalSwap( + const std::string* default_value, ArenaStringPtr* rhs, Arena* rhs_arena, + ArenaStringPtr* lhs, Arena* lhs_arena); + + // Frees storage (if not on an arena). + void Destroy(const std::string* default_value, ::google::protobuf::Arena* arena); + void Destroy(EmptyDefault, ::google::protobuf::Arena* arena); + void Destroy(NonEmptyDefault, ::google::protobuf::Arena* arena); + + // Clears content, but keeps allocated std::string, to avoid the overhead of + // heap operations. After this returns, the content (as seen by the user) will + // always be the empty std::string. Assumes that |default_value| is an empty + // std::string. + void ClearToEmpty(); + + // Clears content, assuming that the current value is not the empty + // string default. + void ClearNonDefaultToEmpty(); + + // Clears content, but keeps allocated std::string if arena != nullptr, to + // avoid the overhead of heap operations. After this returns, the content + // (as seen by the user) will always be equal to |default_value|. + void ClearToDefault(const LazyString& default_value, ::google::protobuf::Arena* arena); + + // Called from generated code / reflection runtime only. Resets value to point + // to a default string pointer, with the semantics that this + // ArenaStringPtr does not own the pointed-to memory. Disregards initial value + // of ptr_ (so this is the *ONLY* safe method to call after construction or + // when reinitializing after becoming the active field in a oneof union). + inline void UnsafeSetDefault(const std::string* default_value); + + // Returns a mutable pointer, but doesn't initialize the string to the + // default value. + std::string* MutableNoArenaNoDefault(const std::string* default_value); + + // Get a mutable pointer with unspecified contents. + // Similar to `MutableNoArenaNoDefault`, but also handles the arena case. + // If the value was donated, the contents are discarded. + std::string* MutableNoCopy(const std::string* default_value, + ::google::protobuf::Arena* arena); + + // Destroy the string. Assumes `arena == nullptr`. + void DestroyNoArena(const std::string* default_value); + + // Internal setter used only at parse time to directly set a donated string + // value. + void UnsafeSetTaggedPointer(TaggedPtr<std::string> value) { + tagged_ptr_ = value; + } + // Generated code only! An optimization, in certain cases the generated + // code is certain we can obtain a std::string with no default checks and + // tag tests. + std::string* UnsafeMutablePointer() PROTOBUF_RETURNS_NONNULL; + + inline bool IsDefault(const std::string* default_value) const { + // Relies on the fact that kPtrTagString == 0, so if IsString(), ptr_ is the + // actual std::string pointer (and if !IsString(), ptr_ will never be equal + // to any aligned |default_value| pointer). The key is that we want to avoid + // masking in the fastpath const-pointer Get() case for non-arena code. + return tagged_ptr_.UnsafeGet() == default_value; + } + + private: + TaggedPtr<std::string> tagged_ptr_; + + bool IsDonatedString() const { return false; } + + // Swaps tagged pointer without debug hardening. This is to allow python + // protobuf to maintain pointer stability even in DEBUG builds. + inline PROTOBUF_NDEBUG_INLINE static void UnsafeShallowSwap( + ArenaStringPtr* rhs, ArenaStringPtr* lhs) { + std::swap(lhs->tagged_ptr_, rhs->tagged_ptr_); + } + + friend class ::google::protobuf::internal::SwapFieldHelper; + + // Slow paths. + + // MutableSlow requires that !IsString() || IsDefault + // Variadic to support 0 args for EmptyDefault and 1 arg for LazyString. + template <typename... Lazy> + std::string* MutableSlow(::google::protobuf::Arena* arena, const Lazy&... lazy_default); + + // Sets value to a newly allocated string and returns it + std::string* SetAndReturnNewString(); + + // Destroys the non-default string value out-of-line + void DestroyNoArenaSlowPath(); + +}; + +inline void ArenaStringPtr::UnsafeSetDefault(const std::string* value) { + tagged_ptr_.Set(const_cast<std::string*>(value)); +} + +// Make sure rhs_arena allocated rhs, and lhs_arena allocated lhs. +inline PROTOBUF_NDEBUG_INLINE void ArenaStringPtr::InternalSwap( // + const std::string* default_value, // + ArenaStringPtr* rhs, Arena* rhs_arena, // + ArenaStringPtr* lhs, Arena* lhs_arena) { + // Silence unused variable warnings in release buildls. + (void)default_value; + (void)rhs_arena; + (void)lhs_arena; + std::swap(lhs->tagged_ptr_, rhs->tagged_ptr_); +#ifdef PROTOBUF_FORCE_COPY_IN_SWAP + auto force_realloc = [default_value](ArenaStringPtr* p, Arena* arena) { + if (p->IsDefault(default_value)) return; + std::string* old_value = p->tagged_ptr_.Get(); + std::string* new_value = + p->IsDonatedString() + ? Arena::Create<std::string>(arena, *old_value) + : Arena::Create<std::string>(arena, std::move(*old_value)); + if (arena == nullptr) delete old_value; + p->tagged_ptr_.Set(new_value); + }; + // Because, at this point, tagged_ptr_ has been swapped, arena should also be + // swapped. + force_realloc(lhs, rhs_arena); + force_realloc(rhs, lhs_arena); +#endif // PROTOBUF_FORCE_COPY_IN_SWAP +} + +inline void ArenaStringPtr::ClearNonDefaultToEmpty() { + // Unconditionally mask away the tag. + tagged_ptr_.Get()->clear(); +} + +inline std::string* ArenaStringPtr::MutableNoArenaNoDefault( + const std::string* default_value) { + // VERY IMPORTANT for performance and code size: this will reduce to a member + // variable load, a pointer check (against |default_value|, in practice a + // static global) and a branch to the slowpath (which calls operator new and + // the ctor). DO NOT add any tagged-pointer operations here. + if (IsDefault(default_value)) { + return SetAndReturnNewString(); + } else { + return UnsafeMutablePointer(); + } +} + +inline void ArenaStringPtr::DestroyNoArena(const std::string* default_value) { + if (!IsDefault(default_value)) { + DestroyNoArenaSlowPath(); + } +} + +inline std::string* ArenaStringPtr::UnsafeMutablePointer() { + GOOGLE_DCHECK(!tagged_ptr_.IsTagged()); + GOOGLE_DCHECK(tagged_ptr_.UnsafeGet() != nullptr); + return tagged_ptr_.UnsafeGet(); +} + + +} // namespace internal +} // namespace protobuf +} // namespace google + +#include <port_undef.inc> + +#endif // GOOGLE_PROTOBUF_ARENASTRING_H__ |