C++那些事之grpc小Demo
github上比较火的rpc有grpc、brpc，腾讯内部比较牛逼的trpc等等，这些rpc支持不同的语言、不同平台。今天来聊聊如何使用grpc，从一个简单的demo入手，整个项目使用CMake构建，一个非常标准的rpc项目管理，所有代码已更新至星球，获取方式见最后的二维码。
1.Step by Step 环境
如果你的电脑是mac，不好意思，暂时用不了最新版本的grpc，最新版本的grpc用了abseil，编译会有问题，官方暂时未解决，如果大家知道如何解决，可以留言，我这边目前未找到解决方法。
所以，建议安装低版本的grpc在你的mac上，或者在linux直接安装，linux上可以使用最新版本grpc，一次安装没有任何问题。
安装方式：
git clone -b v1.57.0 git@github.com:grpc/grpc.git
然后初始化submodule
git submodule update --init
cmake编译安装：
cd cmake
mkdir build
cd build
cmake -DgRPC_INSTALL=ON -DgRPC_BUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=/usr/local/grpc ../..
make -j8
make -j8 install // root 权限
大家可以修改上面的安装目录，注意install时需要root权限。
安装完之后，将你的bin目录配置到path，例如：
export PATH=/usr/local/grpc/bin:$PATH
2.反转字符串Demo
环境搞定了之后，我们便可以上手搞事了。
2.1 协议
第一件事是确定rpc协议：
syntax = "proto3";
package stringreverse;
service StringReverse {
rpc sendRequest (StringRequest) returns (StringReply) {}
}
message StringRequest {
string original = 1;
}
message StringReply {
string reversed = 1;
}
非常简单的协议，请求一个字符串，返回一个字符串。
2.2 客户端
构造rpc请求字符串，然后调用sendRequest接口发送出去即可。
std::string str = "hello world grpc!";
std::cout << "Original string: " << str << std::endl;
StringRequest request;
StringReply reply;
ClientContext context;
request.set_original(str);
Status status = stub->sendRequest(&context, request, &reply);
if (status.ok()) {
std::cout << "Reversed string: " << reply.reversed() << std::endl;
}
// do something
2.3 服务端
通过继承Service实现反转字符串逻辑。
class ReverseServiceImplementation final : public StringReverse::Service {
Status sendRequest(ServerContext* context, const StringRequest* request,
StringReply* reply) override {
// 反转逻辑
}
}
最后注册service即可：
builder.RegisterService(&service);
std::unique_ptr<Server> server(builder.BuildAndStart());
std::cout << "Server listening on port: " << server_address << std::endl;
3.运行
创建编译目录：
mkdir build
cmake ..
# 输出
-- The C compiler identification is GNU 10.2.1
-- The CXX compiler identification is GNU 10.2.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /opt/rh/devtoolset-10/root/usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /opt/rh/devtoolset-10/root/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found Protobuf: /usr/local/grpc/bin/protoc-23.4.0 (found version "23.4.0")
-- Using protobuf
-- Using gRPC 1.57.0
-- Configuring done
-- Generating done
-- Build files have been written to: /code/stringreverse/build
make编译：
[ 10%] Generating stringreverse.pb.cc, stringreverse.pb.h, stringreverse.grpc.pb.cc, stringreverse.grpc.pb.h Scanning dependencies of target server [ 20%] Building CXX object CMakeFiles/server.dir/server.cc.o [ 30%] Building CXX object CMakeFiles/server.dir/stringreverse.pb.cc.o [ 40%] Building CXX object CMakeFiles/server.dir/stringreverse.grpc.pb.cc.o [ 50%] Linking CXX executable server [ 50%] Built target server Scanning dependencies of target client [ 60%] Building CXX object CMakeFiles/client.dir/client.cc.o [ 70%] Building CXX object CMakeFiles/client.dir/stringreverse.pb.cc.o [ 80%] Building CXX object CMakeFiles/client.dir/stringreverse.grpc.pb.cc.o [ 90%] Linking CXX executable client [100%] Built target client
运行server:
[light@i-i339drlk build]$ ./server
Server listening on port: 0.0.0.0:5000
运行client:
[light@i-i339drlk build]$ ./client
Original string: hello world grpc!
Reversed string: !cprg dlrow olleh