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<>什么是gRPC
RPC 即远程过程调用协议（Remote Procedure Call Protocol），可以让我们像调用本地对象一样发起
远程调用。RPC 凭借其强大的治理功能，成为解决分布式系统通信问题的一大利器。
gRPC是一个现代的、高性能、开源的和语言无关的通用 RPC 框架，基于 HTTP2 协议设计，序列化使用
PB(Protocol Buffer)，PB 是一种语言无关的高性能序列化框架，基于 HTTP2+PB 保证了的高性能。
本文介绍如何使用C++利用gRPC来编写client和server的代码。
<>rpc范例的一般编写流程
* 编写proto文件
* 根据proto文件生成对应的.cc和.h文件
* server程序继承service
* client程序使用stub
* 编译server和client程序
<>proto文件编写
syntax = "proto3"; package IM.Login; //生成.h文件后变为IM::Login namespace //定义服务
service ImLogin { //定义服务函数 rpc Regist (IMRegisterReq) returns (IMRegisterRes)
{} rpc Login (IMLoginReq) returns (IMLoginRes) {} }
//注册账号,根据这个生成一个C++类，并自动提供一些修改和获取成员的方法 message IMRegisterReq { string user_name
= 1; string password = 2; } message IMRegisterRes { string user_name = 1;
uint32 user_id = 2; uint32 result_code = 3; } message IMLoginReq { string
user_name = 1; string password = 2; } message IMLoginRes { uint32 user_id = 1;
uint32 result_code = 2; }
输入如下指令生成protobuf序列化后的代码 IM.Login.pb.cc和IM.Login.pb.h：
jyhlinux@ubuntu:~/grpc-v1.45.2/examples/cpp/im_login$ protoc --cpp_out=.
IM.Login.proto // $SRC_DIR: .proto 所在的源目录 // --cpp_out: 生成 c++ 代码 // $DST_DIR:
生成代码的目标目录 // xxx.proto: 要针对哪个 proto 文件生成接口代码 protoc-I=$SRC_DIR --cpp_out=
$DST_DIR $SRC_DIR/xxx.proto
生成的.cc文件和.h文件的类型是什么样呢？举个例子，比如下方proto代码
message IMLoginReq { string user_name = 1; string password = 2; }
生成类似于如下的C++代码：IM.Login.pb.h(不完全)
class IMLoginReq final { // string user_name = 1; void clear_user_name(); void
set_user_name(ArgT0&& arg0, ArgT... args); // string password = 2; void
clear_password(); void set_user_name(ArgT0&& arg0, ArgT... args); };
输入下方指令生成服务框架代码
jyhlinux@ubuntu:~/grpc-v1.45.2/examples/cpp/im_login$ protoc --cpp_out=.
--grpc_out=. --plugin=protoc-gen-grpc=/usr/local/bin/grpc_cpp_plugin
IM.Login.proto
生成服务框架的代码，在当前目录下生成 simple.grpc.pb.h 和 simple.grpc.pb.cc 文件
<>grpc server端代码编写
注意要引入正确的命名空间和头文件
#include <iostream> #include <string> #include <memory> //grpc头文件 #include
<grpcpp/ext/proto_server_reflection_plugin.h> #include <grpcpp/grpcpp.h>
#include <grpcpp/health_check_service_interface.h> #include
"IM.Login.grpc.pb.h" #include "IM.Login.pb.h" using grpc::Server; using
grpc::ServerBuilder; using grpc::ServerContext; using grpc::Status; using
IM::Login::ImLogin; using IM::Login::IMRegisterReq; using
IM::Login::IMRegisterRes; using IM::Login::IMLoginReq; using
IM::Login::IMLoginRes; class IMLoginServiceImpl : public ImLogin::Service{
virtual Status Regist(ServerContext* context, const IMRegisterReq* request,
IMRegisterRes* response) override { std::cout<<"Regist user_name:" <<
request->user_name() << std::endl;
response->set_user_name(request->user_name()); // 这也是插件自动生成的函数 set_属性名()
response->set_user_id(10); response->set_result_code(0); return Status::OK; }
virtual Status Login(ServerContext* context, const IMLoginReq* request,
IMLoginRes* response) override { std::cout << "Login user_name: " <<
request->user_name() << std::endl; response->set_user_id(10);
response->set_result_code(0); return Status::OK; } }; void RunServer() {
std::string server_addr("0.0.0.0:50001"); //服务类实例 IMLoginServiceImpl service;
ServerBuilder builder; //第二参数: The credentials associated with the server.
builder.AddListeningPort(server_addr, grpc::InsecureServerCredentials());
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_TIME_MS, 5000);
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_TIMEOUT_MS, 10000);
//是否允许在没有任何未完成流的情况下发送保持连接的ping包
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_PERMIT_WITHOUT_CALLS, 1);
builder.RegisterService(&service); //创建启动 std::unique_ptr<Server>
server(builder.BuildAndStart()); std::cout << "Server listening on " <<
server_addr << std::endl; server->Wait(); } int main(int argc, const char**
argv) { RunServer(); return 0; }
<>grpc client端
#include <iostream> #include <string> #include <memory> //grpc头文件 #include
<grpcpp/ext/proto_server_reflection_plugin.h> #include <grpcpp/grpcpp.h>
#include <grpcpp/health_check_service_interface.h> #include
"IM.Login.grpc.pb.h" #include "IM.Login.pb.h" using grpc::Channel; using
grpc::ClientContext; using grpc::Status; using IM::Login::ImLogin; using
IM::Login::IMRegisterReq; using IM::Login::IMRegisterRes; using
IM::Login::IMLoginReq; using IM::Login::IMLoginRes; class ImLoginClient{
public: ImLoginClient(std::shared_ptr<Channel> channel)
:stub_(ImLogin::NewStub(channel)){} void Regist(const std::string &user_name,
const std::string &password) { IMRegisterReq request;
request.set_user_name(user_name); request.set_password(password); IMRegisterRes
response; ClientContext context; std::cout << "-> Regist req" << std::endl;
Status status = stub_->Regist(&context, request, &response); if(status.ok()) {
std::cout << "user_name: " << response.user_name() << ", user_id: " <<
response.user_id() << std::endl; } else { std::cout << "user_name: " <<
response.user_name() << ",Regist failed: " << response.result_code() <<
std::endl; } } void Login(const std::string &user_name, const std::string
&password) { IMLoginReq request; request.set_user_name(user_name);
request.set_password(password); IMLoginRes response; ClientContext context;
std::cout << "-> Login req" << std::endl; Status status =
stub_->Login(&context, request, &response); if(status.ok()) { std::cout <<
"user_id: " << response.user_id() << ", login ok" << std::endl; } else {
std::cout << "user_name: " << request.user_name() << ",Login failed: " <<
response.result_code() << std::endl; } } private:
std::unique_ptr<ImLogin::Stub> stub_; }; int main() { std::string server_addr =
"localhost:50001"; ImLoginClient im_login_client(
grpc::CreateChannel(server_addr, grpc::InsecureChannelCredentials()) );
std::string user_name = "jyh"; std::string password = "123456";
im_login_client.Regist(user_name, password); im_login_client.Login(user_name,
password); return 0; }
<>异步gRPC server端代码编写
#include <iostream> #include <string> #include <thread> #include <memory>
#include "IM.Login.grpc.pb.h" #include "IM.Login.pb.h" #include
<grpc/support/log.h> #include <grpcpp/grpcpp.h> using grpc::Server; using
grpc::ServerAsyncResponseWriter; using grpc::ServerBuilder; using
grpc::ServerCompletionQueue; // using grpc::ServerContext; using grpc::Status;
using IM::Login::ImLogin; using IM::Login::IMRegisterReq; using
IM::Login::IMRegisterRes; using IM::Login::IMLoginReq; using
IM::Login::IMLoginRes; class ServerImpl final { public: ~ServerImpl() {
server_->Shutdown(); cq_->Shutdown(); } void Run() { std::string
server_address("0.0.0.0:50001"); //成员初始化 ServerBuilder builder;
builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
builder.RegisterService(&service_); // 初始化service_ cq_ =
builder.AddCompletionQueue(); server_ = builder.BuildAndStart(); // std::cout
<< "Server listening on " << server_address << std::endl; //Proceed to the
server's main loop HandleRpcs(); } private: class CallData{ public:
CallData(ImLogin::AsyncService* service, ServerCompletionQueue* cq)
:service_(service), cq_(cq), status_(CREATE){ std::cout << "CallData
constructing, this:" << this << std::endl; Proceed(); } virtual ~CallData(){}
virtual void Proceed() { return; } //与异步服务器的 gRPC 运行时进行通信的方式。
ImLogin::AsyncService* service_; ServerCompletionQueue *cq_; ServerContext
ctx_; enum CallStatus{CREATE, PROCESS, FINISH}; CallStatus status_; //current
serving state }; class RegistCallData : public CallData { public:
RegistCallData(ImLogin::AsyncService* service, ServerCompletionQueue* cq)
:CallData(service, cq), responder_(&ctx_){ Proceed(); } ~RegistCallData(){}
void Proceed() override { std::cout << "this: " << this <<" RegistCallData
Proceed(), status : " << status_ << std::endl; //状态机 if(status_ == CREATE) {
std::cout << "this: " << this <<" RegistCallData Proceed(), status : " <<
"CREATE" << std::endl; status_ = PROCESS; //
//this唯一标识这个request(故不同实例可并发的服务不同的requests) service_->RequestRegist(&ctx_,
&request_, &responder_, cq_, cq_,this); } else if(status_ == PROCESS) {
std::cout << "this: " << this <<" RegistCallData Proceed(), status : " <<
"PROCESS"<< std::endl; new RegistCallData(service_, cq_); //1. 创建处理逻辑
reply_.set_user_name(request_.user_name()); reply_.set_user_id(10);
reply_.set_result_code(0); status_ = FINISH; responder_.Finish(reply_,
Status::OK, this); } else { std::cout << "this: " << this <<" RegistCallData
Proceed(), status : " << "FINISH"<< std::endl; GPR_ASSERT(status_ == FINISH);
delete this; } } private: IMRegisterReq request_; IMRegisterRes reply_;
ServerAsyncResponseWriter<IMRegisterRes> responder_; }; class LoginCallData :
public CallData { public: LoginCallData(ImLogin::AsyncService* service,
ServerCompletionQueue* cq) :CallData(service, cq), responder_(&ctx_){
Proceed(); } ~LoginCallData(){} void Proceed() override { std::cout << "this: "
<< this <<" LoginCallData Proceed(), status : " << status_ << std::endl; //状态机
if(status_ == CREATE) { std::cout << "this: " << this <<" LoginCallData
Proceed(), status : " << "CREATE" << std::endl; status_ = PROCESS; //
//this唯一标识这个request(故不同实例可并发的服务不同的requests) service_->RequestLogin(&ctx_,
&request_, &responder_, cq_, cq_,this); } else if(status_ == PROCESS) {
std::cout << "this: " << this <<" LoginCallData Proceed(), status : " <<
"PROCESS"<< std::endl; new LoginCallData(service_, cq_); //1. 创建处理逻辑
reply_.set_user_id(10); reply_.set_result_code(0); status_ = FINISH;
responder_.Finish(reply_, Status::OK, this); } else { std::cout << "this: " <<
this <<" LoginCallData Proceed(), status : " << "FINISH"<< std::endl;
GPR_ASSERT(status_ == FINISH); delete this; } } private: IMLoginReq request_;
IMLoginRes reply_; ServerAsyncResponseWriter<IMLoginRes> responder_; }; void
HandleRpcs() { // 可运行在多线程 new RegistCallData(&service_, cq_.get()); // new
LoginCallData(&service_, cq_.get()); void* tag; bool ok; while(true) {
std::cout << "before cq_->Next "<< std::endl; // Read from the queue, blocking
until an event is available or the queue is // shutting down.
GPR_ASSERT(cq_->Next(&tag, &ok)); std::cout << "after cq_->Next " << std::endl;
GPR_ASSERT(ok); std::cout << "before static_cast" << std::endl;
static_cast<CallData*>(tag)->Proceed(); std::cout << "after static_cast" <<
std::endl; } } std::unique_ptr<ServerCompletionQueue> cq_;
ImLogin::AsyncService service_; //与异步服务器的 gRPC 运行时进行通信的方式
std::unique_ptr<Server> server_; }; int main() { ServerImpl server;
server.Run(); return 0; }
<>CMakeLists文件编写
这个CMakeLists.txt是从/grpc-v1.45.2/examples/cpp/helloworld中拷贝出来进行修改的,
这个CMakeLists.txt文件放在稍后会创建的build目录下（examples/cpp/im_login/build/）
#修改的地方用changed标记 cmake_minimum_required(VERSION 3.5.1) project(IMLogin C CXX)
#changed include(../cmake/common.cmake) # Proto file
get_filename_component(im_proto "./IM.Login.proto" ABSOLUTE) #changed
get_filename_component(im_proto_path "${im_proto}" PATH) #changed # Generated
sources set(im_proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/IM.Login.pb.cc")
#changed set(im_proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/IM.Login.pb.h")
#changed set(im_grpc_srcs "${CMAKE_CURRENT_BINARY_DIR}/IM.Login.grpc.pb.cc")
#changed set(im_grpc_hdrs "${CMAKE_CURRENT_BINARY_DIR}/IM.Login.grpc.pb.h")
#changed add_custom_command( #changed OUTPUT "${im_proto_srcs}"
"${im_proto_hdrs}" "${im_grpc_srcs}" "${im_grpc_hdrs}" COMMAND
${_PROTOBUF_PROTOC} ARGS --grpc_out "${CMAKE_CURRENT_BINARY_DIR}" --cpp_out
"${CMAKE_CURRENT_BINARY_DIR}" -I "${im_proto_path}"
--plugin=protoc-gen-grpc="${_GRPC_CPP_PLUGIN_EXECUTABLE}" "${im_proto}" DEPENDS
"${im_proto}") # Include generated *.pb.h files
include_directories("${CMAKE_CURRENT_BINARY_DIR}") # im_grpc_proto #changed
add_library(im_grpc_proto ${im_grpc_srcs} ${im_grpc_hdrs} ${im_proto_srcs}
${im_proto_hdrs}) target_link_libraries(im_grpc_proto ${_REFLECTION}
${_GRPC_GRPCPP} ${_PROTOBUF_LIBPROTOBUF}) # Targets
greeter_[async_](client|server) foreach(_target client server async_server
#生成的可执行程序名 ) add_executable(${_target} "${_target}.cc")
target_link_libraries(${_target} im_grpc_proto ${_REFLECTION} ${_GRPC_GRPCPP}
${_PROTOBUF_LIBPROTOBUF}) endforeach()
<>编译测试
cd ~/grpc-v1.45.2/examples/cpp/im_login/ mkdir build cmake .. make
进行测试1
#终端1执行 ./server #终端2执行 ./client
进行测试2
#终端1执行 ./async_server #终端2执行 ./client
测试结果：
服务端
jyhlinux@ubuntu:~/grpc-v1.45.2/examples/cpp/im_login/build$ ./async_server
Server listening on 0.0.0.0:50001 CallData constructing, this:0x55a0d9d11c50
this: 0x55a0d9d11c50 RegistCallData Proceed(), status : 0 this: 0x55a0d9d11c50
RegistCallData Proceed(), status : CREATE CallData constructing,
this:0x55a0d9d12420 this: 0x55a0d9d12420 LoginCallData Proceed(), status : 0
this: 0x55a0d9d12420 LoginCallData Proceed(), status : CREATE before cq_->Next
after cq_->Next before static_cast this: 0x55a0d9d11c50 RegistCallData
Proceed(), status : 1 this: 0x55a0d9d11c50 RegistCallData Proceed(), status :
PROCESS CallData constructing, this:0x55a0d9d28620 this: 0x55a0d9d28620
RegistCallData Proceed(), status : 0 this: 0x55a0d9d28620 RegistCallData
Proceed(), status : CREATE after static_cast before cq_->Next after cq_->Next
before static_cast this: 0x55a0d9d11c50 RegistCallData Proceed(), status : 2
this: 0x55a0d9d11c50 RegistCallData Proceed(), status : FINISH after
static_cast before cq_->Next after cq_->Next before static_cast this:
0x55a0d9d12420 LoginCallData Proceed(), status : 1 this: 0x55a0d9d12420
LoginCallData Proceed(), status : PROCESS CallData constructing,
this:0x55a0d9d11c50 this: 0x55a0d9d11c50 LoginCallData Proceed(), status : 0
this: 0x55a0d9d11c50 LoginCallData Proceed(), status : CREATE after static_cast
before cq_->Next after cq_->Next before static_cast this: 0x55a0d9d12420
LoginCallData Proceed(), status : 2 this: 0x55a0d9d12420 LoginCallData
Proceed(), status : FINISH after static_cast before cq_->Next
客户端
jyhlinux@ubuntu:~/grpc-v1.45.2/examples/cpp/im_login/build$ ./client -> Regist
req user_name: jyh, user_id: 10 -> Login req user_id: 10, login ok