c++ 使用 gRPC

浅浅的花香味﹌ 2021-09-25 01:10 1015阅读 0赞

# C++ 使用 gRPC #

## 安装 gRPC ##

git clone --recurse-submodules -b v1.34.0 https://github.com/grpc/grpc
    cd grpc
    
    mkdir -p cmake/build
    pushd cmake/build
    cmake -DgRPC_INSTALL=ON -DgRPC_BUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=$(pwd)/install ../..
    make -j
    make install
    popd

## 生成 grpc 代码 ##

export PATH=<安装grpc的路径>/bin:$PATH
    PROTO_PATH=<你的proto文件所在的路径>
    
    protoc -I ./src --grpc_out=./src/ --plugin=protoc-gen-grpc=`which grpc_cpp_plugin` $PROTO_PATH 
    protoc -I ./src --cpp_out=./src// $PROTO_PATH

## 服务端程序 ##

#include <iostream>
    #include <memory>
    #include <string>
    
    #include <grpcpp/grpcpp.h>
    
    #include "helloworld.grpc.pb.h"
    
    using grpc::Server;
    using grpc::ServerBuilder;
    using grpc::ServerContext;
    using grpc::Status;
    
    using HelloWorld::Greeter;
    using HelloWorld::HelloReply;
    using HelloWorld::HelloRequest;
    
    class GreeterServiceImpl final : public Greeter::Service
    { 
        Status SayHello(ServerContext *context,
                        const HelloRequest *request,
                        HelloReply *reply) override
        { 
            std::string prefix("Hi!");
            reply->set_message(prefix + request->text());
            return Status::OK;
        }
    };
    
    void Serve()
    { 
        std::string address("0.0.0.0:50051");
        GreeterServiceImpl serve;
        ServerBuilder builder;
        builder.AddListeningPort(address, grpc::InsecureServerCredentials());
        builder.RegisterService(&serve);
    
        std::unique_ptr<Server> server(builder.BuildAndStart());
        std::cout << "Server listening on " << address << std::endl;
        server->Wait();
    }
    
    int main(int argc, char** argv)
    { 
        Serve();
        return 0;
    }

## 客户端 ##

#include <iostream>
    #include <memory>
    #include <string>
    
    #include <grpcpp/grpcpp.h>
    #ifdef BAZEL_BUILD
    #include "helloworld.grpc.pb.h"
    #else
    #include "helloworld.grpc.pb.h"
    #endif
    
    using grpc::Channel;
    using grpc::ChannelInterface;
    using grpc::ClientContext;
    using grpc::Status;
    
    using HelloWorld::Greeter;
    using HelloWorld::HelloReply;
    using HelloWorld::HelloRequest;
    
    class HelloWorldClient
    { 
    public:
        HelloWorldClient(std::shared_ptr<ChannelInterface> channel)
            : stub_(Greeter::NewStub(channel)) { }
    
        std::string SayHello(const std::string &text)
        { 
            HelloRequest request;
            request.set_text(text);
            HelloReply reply;
            ClientContext context;
    
            Status status = stub_->SayHello(&context, request, &reply);
            if (status.ok())
            { 
                return reply.message();
            }
            std::cerr << status.error_code() << ": " << status.error_message() << std::endl;
            return "RPC failed";
        }
    
    private:
        std::unique_ptr<Greeter::Stub> stub_;
    };
    
    int main(int argc, char** argv)
    { 
        std::string target_str = "localhost:50051";
        HelloWorldClient helloworld_client(grpc::CreateChannel(target_str, grpc::InsecureChannelCredentials()));
        std::string text("Hello World");
        std::string reply = helloworld_client.SayHello(text);
        std::cout << "Received: " << reply << std::endl;
        return 0;
    }

## Makefile 的编写 ##

grpc 可以使用 **pkg-config** 添加依赖，因此我们可以把安装后 **.pc** 文件所在路径添加到 **pkg-config** 的环境变量中。使用 `export PKG_CONFIG_PATH=<你安装grpc后pkgconfig文件夹所在的路径>`。

GRPC_INSTALL_PATH = $(dirname $(pwd))
    export PKG_CONFIG_PATH=$(GRPC_INSTALL_PATH)/grpc/cmake/build/install/lib/pkgconfig
    
    HOST_SYSTEM = $(shell uname | cut -f 1 -d_)
    SYSTEM ?= $(HOST_SYSTEM)
    CXX = g++
    CPPFLAGS += `pkg-config --cflags protobuf grpc`
    CXXFLAGS += -std=c++11
    
    ifeq ($(SYSTEM),Darwin)
    LDFLAGS += -L/usr/local/lib `pkg-config --libs protobuf grpc++`\
    					 -pthread\
               -lgrpc++_reflection\
               -ldl
    else
    LDFLAGS += -L/usr/local/lib `pkg-config --libs protobuf grpc++`\
               -pthread\
               -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed\
               -ldl
    endif
    
    all: helloworld.server helloworld.client
    
    helloworld.server: helloworld.pb.o helloworld.grpc.pb.o helloworld.server.o
    		$(CXX) $^ $(LDFLAGS) -o $@
    
    helloworld.client: helloworld.pb.o helloworld.grpc.pb.o helloworld.client.o
    		$(CXX) $^ $(LDFLAGS) -o $@
    
    clean:
    		rm -f *.o helloworld.server helloworld.client

## 如何使用 ##

在 `Makefile` 所在的文件夹执行如下命令。

make -j
    ./helloworld.server
    
    # 新建一个终端执行下面的命令
    ./helloworld.client

## 全部代码 ##

[cpp-grpc-demo][]

[cpp-grpc-demo]: https://github.com/congjiye/cpp-grpc-demo