1 /* 2 * 3 * Copyright 2015 gRPC authors. 4 * 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 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 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. 16 * 17 */ 18 19 #ifndef GRPCPP_CHANNEL_H 20 #define GRPCPP_CHANNEL_H 21 22 #include <memory> 23 24 #include <grpc/grpc.h> 25 #include <grpcpp/impl/call.h> 26 #include <grpcpp/impl/codegen/channel_interface.h> 27 #include <grpcpp/impl/codegen/config.h> 28 #include <grpcpp/impl/codegen/grpc_library.h> 29 30 struct grpc_channel; 31 32 namespace grpc { 33 34 namespace experimental { 35 /// Resets the channel's connection backoff. 36 /// TODO(roth): Once we see whether this proves useful, either create a gRFC 37 /// and change this to be a method of the Channel class, or remove it. 38 void ChannelResetConnectionBackoff(Channel* channel); 39 } // namespace experimental 40 41 /// Channels represent a connection to an endpoint. Created by \a CreateChannel. 42 class Channel final : public ChannelInterface, 43 public internal::CallHook, 44 public std::enable_shared_from_this<Channel>, 45 private GrpcLibraryCodegen { 46 public: 47 ~Channel(); 48 49 /// Get the current channel state. If the channel is in IDLE and 50 /// \a try_to_connect is set to true, try to connect. 51 grpc_connectivity_state GetState(bool try_to_connect) override; 52 53 /// Returns the LB policy name, or the empty string if not yet available. 54 grpc::string GetLoadBalancingPolicyName() const; 55 56 /// Returns the service config in JSON form, or the empty string if 57 /// not available. 58 grpc::string GetServiceConfigJSON() const; 59 60 private: 61 template <class InputMessage, class OutputMessage> 62 friend class internal::BlockingUnaryCallImpl; 63 friend void experimental::ChannelResetConnectionBackoff(Channel* channel); 64 friend std::shared_ptr<Channel> CreateChannelInternal( 65 const grpc::string& host, grpc_channel* c_channel); 66 Channel(const grpc::string& host, grpc_channel* c_channel); 67 68 internal::Call CreateCall(const internal::RpcMethod& method, 69 ClientContext* context, 70 CompletionQueue* cq) override; 71 void PerformOpsOnCall(internal::CallOpSetInterface* ops, 72 internal::Call* call) override; 73 void* RegisterMethod(const char* method) override; 74 75 void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed, 76 gpr_timespec deadline, CompletionQueue* cq, 77 void* tag) override; 78 bool WaitForStateChangeImpl(grpc_connectivity_state last_observed, 79 gpr_timespec deadline) override; 80 81 CompletionQueue* CallbackCQ() override; 82 83 const grpc::string host_; 84 grpc_channel* const c_channel_; // owned 85 86 // mu_ protects callback_cq_ (the per-channel callbackable completion queue) 87 std::mutex mu_; 88 89 // callback_cq_ references the callbackable completion queue associated 90 // with this channel (if any). It is set on the first call to CallbackCQ(). 91 // It is _not owned_ by the channel; ownership belongs with its internal 92 // shutdown callback tag (invoked when the CQ is fully shutdown). 93 CompletionQueue* callback_cq_ = nullptr; 94 }; 95 96 } // namespace grpc 97 98 #endif // GRPCPP_CHANNEL_H 99