| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_ARGS_H |
| #define GRPC_CORE_LIB_CHANNEL_CHANNEL_ARGS_H |
| |
| #include <grpc/support/port_platform.h> |
| |
| #include <stddef.h> |
| |
| #include <algorithm> // IWYU pragma: keep |
| #include <iosfwd> |
| #include <memory> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/meta/type_traits.h" |
| #include "absl/strings/string_view.h" |
| #include "absl/types/optional.h" |
| #include "absl/types/variant.h" |
| |
| #include <grpc/impl/codegen/grpc_types.h> |
| |
| #include "src/core/lib/avl/avl.h" |
| #include "src/core/lib/gpr/useful.h" |
| #include "src/core/lib/gprpp/debug_location.h" |
| #include "src/core/lib/gprpp/dual_ref_counted.h" |
| #include "src/core/lib/gprpp/ref_counted.h" |
| #include "src/core/lib/gprpp/ref_counted_ptr.h" |
| #include "src/core/lib/gprpp/time.h" |
| #include "src/core/lib/surface/channel_stack_type.h" |
| |
| // Channel args are intentionally immutable, to avoid the need for locking. |
| |
| namespace grpc_core { |
| |
| // Define a traits object for vtable lookup - allows us to integrate with |
| // existing code easily (just define the trait!) and allows some magic in |
| // ChannelArgs to automatically derive a vtable from a T*. |
| // To participate as a pointer, instances should expose the function: |
| // // Gets the vtable for this type |
| // static const grpc_arg_pointer_vtable* VTable(); |
| // // Performs any mutations required for channel args to own a pointer |
| // // Only needed if ChannelArgs::Set is to be called with a raw pointer. |
| // static void* TakeUnownedPointer(T* p); |
| template <typename T, typename Ignored = void /* for SFINAE */> |
| struct ChannelArgTypeTraits; |
| |
| namespace channel_args_detail { |
| inline int PointerCompare(void* a_ptr, const grpc_arg_pointer_vtable* a_vtable, |
| void* b_ptr, |
| const grpc_arg_pointer_vtable* b_vtable) { |
| int c = QsortCompare(a_ptr, b_ptr); |
| if (c == 0) return 0; |
| c = QsortCompare(a_vtable, b_vtable); |
| if (c != 0) return c; |
| return a_vtable->cmp(a_ptr, b_ptr); |
| } |
| |
| // The type returned by calling Ref() on a T - used to determine the basest-type |
| // before the crt refcount base class. |
| template <typename T> |
| using RefType = absl::remove_cvref_t<decltype(*std::declval<T>().Ref())>; |
| } // namespace channel_args_detail |
| |
| // Specialization for ref-counted pointers. |
| // Types should expose: |
| // static int ChannelArgsCompare(const T* a, const T* b); |
| template <typename T> |
| struct ChannelArgTypeTraits< |
| T, absl::enable_if_t< |
| std::is_base_of<RefCounted<channel_args_detail::RefType<T>>, |
| channel_args_detail::RefType<T>>::value || |
| std::is_base_of<RefCounted<channel_args_detail::RefType<T>, |
| NonPolymorphicRefCount>, |
| channel_args_detail::RefType<T>>::value || |
| std::is_base_of<DualRefCounted<channel_args_detail::RefType<T>>, |
| channel_args_detail::RefType<T>>::value, |
| void>> { |
| static const grpc_arg_pointer_vtable* VTable() { |
| static const grpc_arg_pointer_vtable tbl = { |
| // copy |
| [](void* p) -> void* { |
| return p == nullptr ? nullptr |
| : static_cast<T*>(p) |
| ->Ref(DEBUG_LOCATION, "ChannelArgs copy") |
| .release(); |
| }, |
| // destroy |
| [](void* p) { |
| if (p != nullptr) { |
| static_cast<T*>(p)->Unref(DEBUG_LOCATION, "ChannelArgs destroy"); |
| } |
| }, |
| // compare |
| [](void* p1, void* p2) { |
| return T::ChannelArgsCompare(static_cast<const T*>(p1), |
| static_cast<const T*>(p2)); |
| }, |
| }; |
| return &tbl; |
| }; |
| }; |
| |
| // Specialization for shared_ptr |
| // Incurs an allocation because shared_ptr.release is not a thing. |
| template <typename T> |
| struct is_shared_ptr : std::false_type {}; |
| template <typename T> |
| struct is_shared_ptr<std::shared_ptr<T>> : std::true_type {}; |
| template <typename T> |
| struct ChannelArgTypeTraits<T, |
| absl::enable_if_t<is_shared_ptr<T>::value, void>> { |
| static void* TakeUnownedPointer(T* p) { return p; } |
| static const grpc_arg_pointer_vtable* VTable() { |
| static const grpc_arg_pointer_vtable tbl = { |
| // copy |
| [](void* p) -> void* { return new T(*static_cast<T*>(p)); }, |
| // destroy |
| [](void* p) { delete static_cast<T*>(p); }, |
| // compare |
| [](void* p1, void* p2) { |
| return QsortCompare(static_cast<const T*>(p1)->get(), |
| static_cast<const T*>(p2)->get()); |
| }, |
| }; |
| return &tbl; |
| }; |
| }; |
| |
| // If a type declares some member 'struct RawPointerChannelArgTag {}' then |
| // we automatically generate a vtable for it that does not do any ownership |
| // management and compares the type by pointer identity. |
| // This is intended to be relatively ugly because *most types should worry about |
| // ownership*. |
| template <typename T> |
| struct ChannelArgTypeTraits<T, |
| absl::void_t<typename T::RawPointerChannelArgTag>> { |
| static void* TakeUnownedPointer(T* p) { return p; } |
| static const grpc_arg_pointer_vtable* VTable() { |
| static const grpc_arg_pointer_vtable tbl = { |
| // copy |
| [](void* p) -> void* { return p; }, |
| // destroy |
| [](void*) {}, |
| // compare |
| [](void* p1, void* p2) { return QsortCompare(p1, p2); }, |
| }; |
| return &tbl; |
| }; |
| }; |
| |
| // GetObject support for shared_ptr and RefCountedPtr |
| template <typename T> |
| struct WrapInSharedPtr |
| : std::integral_constant< |
| bool, std::is_base_of<std::enable_shared_from_this<T>, T>::value> {}; |
| template <typename T, typename Ignored = void /* for SFINAE */> |
| struct GetObjectImpl; |
| // std::shared_ptr implementation |
| template <typename T> |
| struct GetObjectImpl<T, absl::enable_if_t<WrapInSharedPtr<T>::value, void>> { |
| using Result = T*; |
| using ReffedResult = std::shared_ptr<T>; |
| using StoredType = std::shared_ptr<T>*; |
| static Result Get(StoredType p) { return p->get(); }; |
| static ReffedResult GetReffed(StoredType p) { return ReffedResult(*p); }; |
| static ReffedResult GetReffed(StoredType p, |
| const DebugLocation& /* location */, |
| const char* /* reason */) { |
| return GetReffed(*p); |
| }; |
| }; |
| // RefCountedPtr |
| template <typename T> |
| struct GetObjectImpl<T, absl::enable_if_t<!WrapInSharedPtr<T>::value, void>> { |
| using Result = T*; |
| using ReffedResult = RefCountedPtr<T>; |
| using StoredType = Result; |
| static Result Get(StoredType p) { return p; }; |
| static ReffedResult GetReffed(StoredType p) { |
| if (p == nullptr) return nullptr; |
| return p->Ref(); |
| }; |
| static ReffedResult GetReffed(StoredType p, const DebugLocation& location, |
| const char* reason) { |
| if (p == nullptr) return nullptr; |
| return p->Ref(location, reason); |
| }; |
| }; |
| |
| // Provide the canonical name for a type's channel arg key |
| template <typename T> |
| struct ChannelArgNameTraits { |
| static absl::string_view ChannelArgName() { return T::ChannelArgName(); } |
| }; |
| template <typename T> |
| struct ChannelArgNameTraits<std::shared_ptr<T>> { |
| static absl::string_view ChannelArgName() { return T::ChannelArgName(); } |
| }; |
| |
| class ChannelArgs { |
| public: |
| class Pointer { |
| public: |
| Pointer(void* p, const grpc_arg_pointer_vtable* vtable); |
| ~Pointer() { vtable_->destroy(p_); } |
| |
| Pointer(const Pointer& other); |
| Pointer& operator=(Pointer other) { |
| std::swap(p_, other.p_); |
| std::swap(vtable_, other.vtable_); |
| return *this; |
| } |
| Pointer(Pointer&& other) noexcept; |
| Pointer& operator=(Pointer&& other) noexcept { |
| std::swap(p_, other.p_); |
| std::swap(vtable_, other.vtable_); |
| return *this; |
| } |
| |
| friend int QsortCompare(const Pointer& a, const Pointer& b) { |
| return channel_args_detail::PointerCompare(a.p_, a.vtable_, b.p_, |
| b.vtable_); |
| } |
| |
| bool operator==(const Pointer& rhs) const { |
| return QsortCompare(*this, rhs) == 0; |
| } |
| bool operator<(const Pointer& rhs) const { |
| return QsortCompare(*this, rhs) < 0; |
| } |
| bool operator!=(const Pointer& rhs) const { |
| return QsortCompare(*this, rhs) != 0; |
| } |
| |
| void* c_pointer() const { return p_; } |
| const grpc_arg_pointer_vtable* c_vtable() const { return vtable_; } |
| |
| private: |
| static const grpc_arg_pointer_vtable* EmptyVTable(); |
| |
| void* p_; |
| const grpc_arg_pointer_vtable* vtable_; |
| }; |
| |
| using Value = absl::variant<int, std::string, Pointer>; |
| |
| struct ChannelArgsDeleter { |
| void operator()(const grpc_channel_args* p) const; |
| }; |
| using CPtr = |
| std::unique_ptr<const grpc_channel_args, ChannelArgs::ChannelArgsDeleter>; |
| |
| ChannelArgs(); |
| ~ChannelArgs(); |
| ChannelArgs(const ChannelArgs&); |
| ChannelArgs& operator=(const ChannelArgs&); |
| ChannelArgs(ChannelArgs&&) noexcept; |
| ChannelArgs& operator=(ChannelArgs&&) noexcept; |
| |
| static ChannelArgs FromC(const grpc_channel_args* args); |
| static ChannelArgs FromC(const grpc_channel_args& args) { |
| return FromC(&args); |
| } |
| // Construct a new grpc_channel_args struct. |
| CPtr ToC() const; |
| |
| // Returns the union of this channel args with other. |
| // If a key is present in both, the value from this is used. |
| GRPC_MUST_USE_RESULT ChannelArgs UnionWith(ChannelArgs other) const; |
| |
| const Value* Get(absl::string_view name) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, |
| Pointer value) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, int value) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, |
| absl::string_view value) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, |
| std::string value) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, |
| const char* value) const; |
| GRPC_MUST_USE_RESULT ChannelArgs Set(grpc_arg arg) const; |
| template <typename T> |
| GRPC_MUST_USE_RESULT absl::enable_if_t< |
| std::is_same<const grpc_arg_pointer_vtable*, |
| decltype(ChannelArgTypeTraits<T>::VTable())>::value, |
| ChannelArgs> |
| Set(absl::string_view name, T* value) const { |
| return Set(name, Pointer(ChannelArgTypeTraits<T>::TakeUnownedPointer(value), |
| ChannelArgTypeTraits<T>::VTable())); |
| } |
| template <typename T> |
| GRPC_MUST_USE_RESULT auto Set(absl::string_view name, |
| RefCountedPtr<T> value) const |
| -> absl::enable_if_t< |
| std::is_same<const grpc_arg_pointer_vtable*, |
| decltype(ChannelArgTypeTraits< |
| absl::remove_cvref_t<T>>::VTable())>::value, |
| ChannelArgs> { |
| return Set( |
| name, Pointer(value.release(), |
| ChannelArgTypeTraits<absl::remove_cvref_t<T>>::VTable())); |
| } |
| template <typename T> |
| GRPC_MUST_USE_RESULT absl::enable_if_t< |
| std::is_same< |
| const grpc_arg_pointer_vtable*, |
| decltype(ChannelArgTypeTraits<std::shared_ptr<T>>::VTable())>::value, |
| ChannelArgs> |
| Set(absl::string_view name, std::shared_ptr<T> value) const { |
| auto* store_value = new std::shared_ptr<T>(value); |
| return Set( |
| name, |
| Pointer(ChannelArgTypeTraits<std::shared_ptr<T>>::TakeUnownedPointer( |
| store_value), |
| ChannelArgTypeTraits<std::shared_ptr<T>>::VTable())); |
| } |
| template <typename T> |
| GRPC_MUST_USE_RESULT ChannelArgs SetIfUnset(absl::string_view name, |
| T value) const { |
| if (Contains(name)) return *this; |
| return Set(name, std::move(value)); |
| } |
| GRPC_MUST_USE_RESULT ChannelArgs Remove(absl::string_view name) const; |
| bool Contains(absl::string_view name) const; |
| |
| template <typename T> |
| bool ContainsObject() const { |
| return Get(ChannelArgNameTraits<T>::ChannelArgName()) != nullptr; |
| } |
| |
| absl::optional<int> GetInt(absl::string_view name) const; |
| absl::optional<absl::string_view> GetString(absl::string_view name) const; |
| absl::optional<std::string> GetOwnedString(absl::string_view name) const; |
| void* GetVoidPointer(absl::string_view name) const; |
| template <typename T> |
| typename GetObjectImpl<T>::StoredType GetPointer( |
| absl::string_view name) const { |
| return static_cast<typename GetObjectImpl<T>::StoredType>( |
| GetVoidPointer(name)); |
| } |
| absl::optional<Duration> GetDurationFromIntMillis( |
| absl::string_view name) const; |
| absl::optional<bool> GetBool(absl::string_view name) const; |
| |
| // Object based get/set. |
| // Deal with the common case that we set a pointer to an object under |
| // the same name in every usage. |
| // Expects ChannelArgTypeTraits to exist for T, and T to expose: |
| // static string_view ChannelArgName(); |
| template <typename T> |
| GRPC_MUST_USE_RESULT ChannelArgs SetObject(T* p) const { |
| return Set(T::ChannelArgName(), p); |
| } |
| template <typename T> |
| GRPC_MUST_USE_RESULT ChannelArgs SetObject(RefCountedPtr<T> p) const { |
| return Set(T::ChannelArgName(), std::move(p)); |
| } |
| template <typename T> |
| GRPC_MUST_USE_RESULT ChannelArgs SetObject(std::shared_ptr<T> p) const { |
| return Set(ChannelArgNameTraits<T>::ChannelArgName(), std::move(p)); |
| } |
| template <typename T> |
| typename GetObjectImpl<T>::Result GetObject() const { |
| return GetObjectImpl<T>::Get( |
| GetPointer<T>(ChannelArgNameTraits<T>::ChannelArgName())); |
| } |
| template <typename T> |
| typename GetObjectImpl<T>::ReffedResult GetObjectRef() const { |
| return GetObjectImpl<T>::GetReffed( |
| GetPointer<T>(ChannelArgNameTraits<T>::ChannelArgName())); |
| } |
| template <typename T> |
| typename GetObjectImpl<T>::ReffedResult GetObjectRef( |
| const DebugLocation& location, const char* reason) const { |
| return GetObjectImpl<T>::GetReffed( |
| GetPointer<T>(ChannelArgNameTraits<T>::ChannelArgName()), location, |
| reason); |
| } |
| |
| bool operator!=(const ChannelArgs& other) const; |
| bool operator<(const ChannelArgs& other) const; |
| bool operator==(const ChannelArgs& other) const; |
| |
| // Helpers for commonly accessed things |
| |
| bool WantMinimalStack() const; |
| std::string ToString() const; |
| |
| private: |
| explicit ChannelArgs(AVL<std::string, Value> args); |
| |
| GRPC_MUST_USE_RESULT ChannelArgs Set(absl::string_view name, |
| Value value) const; |
| |
| AVL<std::string, Value> args_; |
| }; |
| |
| std::ostream& operator<<(std::ostream& out, const ChannelArgs& args); |
| |
| } // namespace grpc_core |
| |
| /** Copy the arguments in \a src into a new instance */ |
| grpc_channel_args* grpc_channel_args_copy(const grpc_channel_args* src); |
| |
| /** Copy the arguments in \a src into a new instance, stably sorting keys */ |
| grpc_channel_args* grpc_channel_args_normalize(const grpc_channel_args* src); |
| |
| /** Copy the arguments in \a src and append \a to_add. If \a to_add is NULL, it |
| * is equivalent to calling \a grpc_channel_args_copy. */ |
| grpc_channel_args* grpc_channel_args_copy_and_add(const grpc_channel_args* src, |
| const grpc_arg* to_add, |
| size_t num_to_add); |
| |
| /** Copies the arguments in \a src except for those whose keys are in |
| \a to_remove. */ |
| grpc_channel_args* grpc_channel_args_copy_and_remove( |
| const grpc_channel_args* src, const char** to_remove, size_t num_to_remove); |
| |
| /** Copies the arguments from \a src except for those whose keys are in |
| \a to_remove and appends the arguments in \a to_add. */ |
| grpc_channel_args* grpc_channel_args_copy_and_add_and_remove( |
| const grpc_channel_args* src, const char** to_remove, size_t num_to_remove, |
| const grpc_arg* to_add, size_t num_to_add); |
| |
| /** Perform the union of \a a and \a b, prioritizing \a a entries */ |
| grpc_channel_args* grpc_channel_args_union(const grpc_channel_args* a, |
| const grpc_channel_args* b); |
| |
| /** Destroy arguments created by \a grpc_channel_args_copy */ |
| void grpc_channel_args_destroy(grpc_channel_args* a); |
| inline void grpc_channel_args_destroy(const grpc_channel_args* a) { |
| grpc_channel_args_destroy(const_cast<grpc_channel_args*>(a)); |
| } |
| |
| int grpc_channel_args_compare(const grpc_channel_args* a, |
| const grpc_channel_args* b); |
| |
| /** Returns the value of argument \a name from \a args, or NULL if not found. */ |
| const grpc_arg* grpc_channel_args_find(const grpc_channel_args* args, |
| const char* name); |
| |
| bool grpc_channel_args_want_minimal_stack(const grpc_channel_args* args); |
| |
| typedef struct grpc_integer_options { |
| int default_value; // Return this if value is outside of expected bounds. |
| int min_value; |
| int max_value; |
| } grpc_integer_options; |
| |
| /** Returns the value of \a arg, subject to the constraints in \a options. */ |
| int grpc_channel_arg_get_integer(const grpc_arg* arg, |
| const grpc_integer_options options); |
| /** Similar to the above, but needs to find the arg from \a args by the name |
| * first. */ |
| int grpc_channel_args_find_integer(const grpc_channel_args* args, |
| const char* name, |
| const grpc_integer_options options); |
| |
| /** Returns the value of \a arg if \a arg is of type GRPC_ARG_STRING. |
| Otherwise, emits a warning log, and returns nullptr. |
| If arg is nullptr, returns nullptr, and does not emit a warning. */ |
| char* grpc_channel_arg_get_string(const grpc_arg* arg); |
| /** Similar to the above, but needs to find the arg from \a args by the name |
| * first. */ |
| char* grpc_channel_args_find_string(const grpc_channel_args* args, |
| const char* name); |
| /** If \a arg is of type GRPC_ARG_INTEGER, returns true if it's non-zero. |
| * Returns \a default_value if \a arg is of other types. */ |
| bool grpc_channel_arg_get_bool(const grpc_arg* arg, bool default_value); |
| /** Similar to the above, but needs to find the arg from \a args by the name |
| * first. */ |
| bool grpc_channel_args_find_bool(const grpc_channel_args* args, |
| const char* name, bool default_value); |
| |
| template <typename T> |
| T* grpc_channel_args_find_pointer(const grpc_channel_args* args, |
| const char* name) { |
| const grpc_arg* arg = grpc_channel_args_find(args, name); |
| if (arg == nullptr || arg->type != GRPC_ARG_POINTER) return nullptr; |
| return static_cast<T*>(arg->value.pointer.p); |
| } |
| |
| // Helpers for creating channel args. |
| grpc_arg grpc_channel_arg_string_create(char* name, char* value); |
| grpc_arg grpc_channel_arg_integer_create(char* name, int value); |
| grpc_arg grpc_channel_arg_pointer_create(char* name, void* value, |
| const grpc_arg_pointer_vtable* vtable); |
| |
| // Returns a string representing channel args in human-readable form. |
| std::string grpc_channel_args_string(const grpc_channel_args* args); |
| |
| namespace grpc_core { |
| // Ensure no duplicate channel args (with some backwards compatibility hacks). |
| // Eliminate any grpc.internal.* args. |
| // Return a C++ object. |
| ChannelArgs ChannelArgsBuiltinPrecondition(const grpc_channel_args* src); |
| } // namespace grpc_core |
| |
| // Takes ownership of the old_args |
| typedef grpc_core::ChannelArgs ( |
| *grpc_channel_args_client_channel_creation_mutator)( |
| const char* target, const grpc_core::ChannelArgs& old_args, |
| grpc_channel_stack_type type); |
| |
| // Should be called only once globaly before grpc is init'ed. |
| void grpc_channel_args_set_client_channel_creation_mutator( |
| grpc_channel_args_client_channel_creation_mutator cb); |
| // This will be called at the creation of each channel. |
| grpc_channel_args_client_channel_creation_mutator |
| grpc_channel_args_get_client_channel_creation_mutator(); |
| |
| #endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_ARGS_H */ |