3 * Copyright 2018 gRPC authors.
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
19 #ifndef GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
20 #define GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
25 #include <grpcpp/impl/codegen/interceptor.h>
26 #include <grpcpp/impl/codegen/rpc_method.h>
27 #include <grpcpp/impl/codegen/string_ref.h>
35 class InterceptorBatchMethodsImpl;
38 namespace experimental {
41 // A factory interface for creation of client interceptors. A vector of
42 // factories can be provided at channel creation which will be used to create a
43 // new vector of client interceptors per RPC. Client interceptor authors should
44 // create a subclass of ClientInterceptorFactorInterface which creates objects
45 // of their interceptors.
46 class ClientInterceptorFactoryInterface {
48 virtual ~ClientInterceptorFactoryInterface() {}
49 // Returns a pointer to an Interceptor object on successful creation, nullptr
50 // otherwise. If nullptr is returned, this server interceptor factory is
51 // ignored for the purposes of that RPC.
52 virtual Interceptor* CreateClientInterceptor(ClientRpcInfo* info) = 0;
54 } // namespace experimental
57 extern experimental::ClientInterceptorFactoryInterface*
58 g_global_client_interceptor_factory;
61 /// ClientRpcInfo represents the state of a particular RPC as it
62 /// appears to an interceptor. It is created and owned by the library and
63 /// passed to the CreateClientInterceptor method of the application's
64 /// ClientInterceptorFactoryInterface implementation
65 namespace experimental {
68 // TODO(yashykt): Stop default-constructing ClientRpcInfo and remove UNKNOWN
69 // from the list of possible Types.
70 /// Type categorizes RPCs by unary or streaming type
76 UNKNOWN // UNKNOWN is not API and will be removed later
81 // Delete copy constructor but allow default move constructor
82 ClientRpcInfo(const ClientRpcInfo&) = delete;
83 ClientRpcInfo(ClientRpcInfo&&) = default;
87 /// Return the fully-specified method name
88 const char* method() const { return method_; }
90 /// Return a pointer to the channel on which the RPC is being sent
91 ChannelInterface* channel() { return channel_; }
93 /// Return a pointer to the underlying ClientContext structure associated
94 /// with the RPC to support features that apply to it
95 grpc::ClientContext* client_context() { return ctx_; }
97 /// Return the type of the RPC (unary or a streaming flavor)
98 Type type() const { return type_; }
101 static_assert(Type::UNARY ==
102 static_cast<Type>(internal::RpcMethod::NORMAL_RPC),
103 "violated expectation about Type enum");
104 static_assert(Type::CLIENT_STREAMING ==
105 static_cast<Type>(internal::RpcMethod::CLIENT_STREAMING),
106 "violated expectation about Type enum");
107 static_assert(Type::SERVER_STREAMING ==
108 static_cast<Type>(internal::RpcMethod::SERVER_STREAMING),
109 "violated expectation about Type enum");
110 static_assert(Type::BIDI_STREAMING ==
111 static_cast<Type>(internal::RpcMethod::BIDI_STREAMING),
112 "violated expectation about Type enum");
114 // Default constructor should only be used by ClientContext
115 ClientRpcInfo() = default;
117 // Constructor will only be called from ClientContext
118 ClientRpcInfo(grpc::ClientContext* ctx, internal::RpcMethod::RpcType type,
119 const char* method, grpc::ChannelInterface* channel)
121 type_(static_cast<Type>(type)),
125 // Move assignment should only be used by ClientContext
126 // TODO(yashykt): Delete move assignment
127 ClientRpcInfo& operator=(ClientRpcInfo&&) = default;
129 // Runs interceptor at pos \a pos.
131 experimental::InterceptorBatchMethods* interceptor_methods, size_t pos) {
132 GPR_CODEGEN_ASSERT(pos < interceptors_.size());
133 interceptors_[pos]->Intercept(interceptor_methods);
136 void RegisterInterceptors(
137 const std::vector<std::unique_ptr<
138 experimental::ClientInterceptorFactoryInterface>>& creators,
139 size_t interceptor_pos) {
140 if (interceptor_pos > creators.size()) {
141 // No interceptors to register
144 for (auto it = creators.begin() + interceptor_pos; it != creators.end();
146 auto* interceptor = (*it)->CreateClientInterceptor(this);
147 if (interceptor != nullptr) {
148 interceptors_.push_back(
149 std::unique_ptr<experimental::Interceptor>(interceptor));
152 if (internal::g_global_client_interceptor_factory != nullptr) {
153 interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
154 internal::g_global_client_interceptor_factory
155 ->CreateClientInterceptor(this)));
159 grpc::ClientContext* ctx_ = nullptr;
160 // TODO(yashykt): make type_ const once move-assignment is deleted
161 Type type_{Type::UNKNOWN};
162 const char* method_ = nullptr;
163 grpc::ChannelInterface* channel_ = nullptr;
164 std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
165 bool hijacked_ = false;
166 size_t hijacked_interceptor_ = 0;
168 friend class internal::InterceptorBatchMethodsImpl;
169 friend class grpc::ClientContext;
172 // PLEASE DO NOT USE THIS. ALWAYS PREFER PER CHANNEL INTERCEPTORS OVER A GLOBAL
173 // INTERCEPTOR. IF USAGE IS ABSOLUTELY NECESSARY, PLEASE READ THE SAFETY NOTES.
174 // Registers a global client interceptor factory object, which is used for all
175 // RPCs made in this process. The application is responsible for maintaining the
176 // life of the object while gRPC operations are in progress. The global
177 // interceptor factory should only be registered once at the start of the
178 // process before any gRPC operations have begun.
179 void RegisterGlobalClientInterceptorFactory(
180 ClientInterceptorFactoryInterface* factory);
182 // For testing purposes only
183 void TestOnlyResetGlobalClientInterceptorFactory();
185 } // namespace experimental
188 #endif // GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H