grpc+protobuf 的C++ service 生成pb.cc，pb.h实例解析

这篇文章将会简单的描述一下grpc+protobuf 的C++ service的搭建过程，告诉读者在linux系统下怎样实现一个service接口的流程。

一、.proto文件的

实现一个简单的helloworld回显功能，首先需要一个.proto文件，我将它命名为example.proto，文件内容如下：

[cpp] view plain copy print ?

1. syntax = "proto3";  
2.   
3. message SearchRequest  
4. {  
5.     string Request = 1;  
6. }  
7.   
8. message SearchResponse  
9. {  
10.     string Response = 2;  
11. }  
12.   
13. service SearchService {  
14.         rpc Search (SearchRequest) returns (SearchResponse);  
15. }  

syntax = "proto3";

	message SearchRequest
	{
		string Request = 1;
	}

	message SearchResponse
	{
		string Response = 2;
	}

	service SearchService {
  		rpc Search (SearchRequest) returns (SearchResponse);
	}

二、自动生成代码

使用example.proto文件自动生成grpc和protobuf的代码

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1. protoc --cpp_out=./ examples.proto  
2. protoc --grpc_out=./ --plugin=protoc-gen-grpc=/usr/local/bin/grpc_cpp_plugin examples.proto  

protoc --cpp_out=./ examples.proto
protoc --grpc_out=./ --plugin=protoc-gen-grpc=/usr/local/bin/grpc_cpp_plugin examples.proto

这两个命令将会生成四个文件， examples.grpc.pb.cc、examples.grpc.pb.h、examples.pb.cc、examples.pb.h。

三、服务器代码

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1. #include <iostream>  
2. #include <memory>  
3. #include <string>  
4.   
5. #include <grpc++/grpc++.h>  
6. #include <grpc/grpc.h>  
7. #include <grpc++/server.h>  
8. #include <grpc++/server_builder.h>  
9. #include <grpc++/server_context.h>  
10.   
11. #include "examples.grpc.pb.h"  
12.   
13. using grpc::Server;  
14. using grpc::ServerBuilder;  
15. using grpc::ServerContext;  
16. using grpc::Status;  
17.   
18. class SearchRequestImpl final : public SearchService::Service {  
19.   Status Search(ServerContext* context, const SearchRequest* request,  
20.                   SearchResponse* reply) override {  
21.     std::string prefix("Hello ");  
22.     reply->set_response(prefix + request->request());  
23.     return Status::OK;  
24.   }  
25. };  
26.   
27. void RunServer() {  
28.   std::string server_address("0.0.0.0:50051");  
29.   SearchRequestImpl service;  
30.   
31.   ServerBuilder builder;  
32.   builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());  
33.   builder.RegisterService(&service);  
34.   std::unique_ptr<Server> server(builder.BuildAndStart());  
35.   std::cout << "Server listening on " << server_address << std::endl;  
36.   
37.   server->Wait();  
38. }  
39.   
40. int main(int argc, char** argv) {  
41.   RunServer();  
42.   
43.   return 0;  
44. }  

#include <iostream>
#include <memory>
#include <string>

#include <grpc++/grpc++.h>
#include <grpc/grpc.h>
#include <grpc++/server.h>
#include <grpc++/server_builder.h>
#include <grpc++/server_context.h>

#include "examples.grpc.pb.h"

using grpc::Server;
using grpc::ServerBuilder;
using grpc::ServerContext;
using grpc::Status;

class SearchRequestImpl final : public SearchService::Service {
  Status Search(ServerContext* context, const SearchRequest* request,
                  SearchResponse* reply) override {
    std::string prefix("Hello ");
    reply->set_response(prefix + request->request());
    return Status::OK;
  }
};

void RunServer() {
  std::string server_address("0.0.0.0:50051");
  SearchRequestImpl service;

  ServerBuilder builder;
  builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
  builder.RegisterService(&service);
  std::unique_ptr<Server> server(builder.BuildAndStart());
  std::cout << "Server listening on " << server_address << std::endl;

  server->Wait();
}

int main(int argc, char** argv) {
  RunServer();

  return 0;
}

四、客户端代码

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1. #include <iostream>  
2. #include <memory>  
3. #include <string>  
4.   
5. #include <grpc++/grpc++.h>  
6. #include <grpc/support/log.h>  
7.   
8. #include "examples.grpc.pb.h"  
9.   
10. using grpc::Channel;  
11. using grpc::ClientAsyncResponseReader;  
12. using grpc::ClientContext;  
13. using grpc::CompletionQueue;  
14. using grpc::Status;  
15.   
16.   
17. class ExampleClient {  
18.  public:  
19.   explicit ExampleClient(std::shared_ptr<Channel> channel)  
20.       : stub_(SearchService::NewStub(channel)) {}  
21.    
22.   std::string Search(const std::string& user) {  
23.    
24.     SearchRequest request;  
25.     request.set_request(user);  
26.    
27.     SearchResponse reply;  
28.      
29.     ClientContext context;  
30.   
31.     CompletionQueue cq;  
32.   
33.     Status status;  
34.   
35.     std::unique_ptr<ClientAsyncResponseReader<SearchResponse> > rpc(  
36.         stub_->AsyncSearch(&context, request, &cq));  
37.   
38.     rpc->Finish(&reply, &status, (void*)1);  
39.     void* got_tag;  
40.     bool ok = false;  
41.     
42.     GPR_ASSERT(cq.Next(&got_tag, &ok));  
43.   
44.      
45.     GPR_ASSERT(got_tag == (void*)1);  
46.     
47.     GPR_ASSERT(ok);  
48.   
49.     if (status.ok()) {  
50.       return reply.response();  
51.     } else {  
52.       return "RPC failed";  
53.     }  
54.   }  
55.   
56.  private:  
57.    
58.   std::unique_ptr<SearchService::Stub> stub_;  
59. };  
60.   
61. int main(int argc, char** argv) {  
62.   ExampleClient client(grpc::CreateChannel(  
63.       "localhost:50051", grpc::InsecureChannelCredentials()));  
64.   std::string user("world");  
65.   std::string reply = client.Search(user);  // The actual RPC call!  
66.   std::cout << "client received: " << reply << std::endl;  
67.   
68.   return 0;  
69. }  

#include <iostream>
#include <memory>
#include <string>

#include <grpc++/grpc++.h>
#include <grpc/support/log.h>

#include "examples.grpc.pb.h"

using grpc::Channel;
using grpc::ClientAsyncResponseReader;
using grpc::ClientContext;
using grpc::CompletionQueue;
using grpc::Status;


class ExampleClient {
 public:
  explicit ExampleClient(std::shared_ptr<Channel> channel)
      : stub_(SearchService::NewStub(channel)) {}
 
  std::string Search(const std::string& user) {
 
    SearchRequest request;
    request.set_request(user);
 
    SearchResponse reply;
   
    ClientContext context;

    CompletionQueue cq;

    Status status;

    std::unique_ptr<ClientAsyncResponseReader<SearchResponse> > rpc(
        stub_->AsyncSearch(&context, request, &cq));

    rpc->Finish(&reply, &status, (void*)1);
    void* got_tag;
    bool ok = false;
  
    GPR_ASSERT(cq.Next(&got_tag, &ok));

   
    GPR_ASSERT(got_tag == (void*)1);
  
    GPR_ASSERT(ok);

    if (status.ok()) {
      return reply.response();
    } else {
      return "RPC failed";
    }
  }

 private:
 
  std::unique_ptr<SearchService::Stub> stub_;
};

int main(int argc, char** argv) {
  ExampleClient client(grpc::CreateChannel(
      "localhost:50051", grpc::InsecureChannelCredentials()));
  std::string user("world");
  std::string reply = client.Search(user);  // The actual RPC call!
  std::cout << "client received: " << reply << std::endl;

  return 0;
}

五、Makefile文件

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1. subdir = ./  
2.   
3. export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig  
4.   
5. SOURCES = $(wildcard $(subdir)*.cc)  
6. SRCOBJS = $(patsubst %.cc,%.o,$(SOURCES))  
7. CC = g++  
8.   
9. %.o:%.cc  
10.     $(CC) -std=c++11 -I/usr/local/include -pthread -c $< -o $@  
11.   
12. all: client server  
13.   
14. client: examples.grpc.pb.o examples.pb.o examples_client.o  
15.     $(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@  
16.   
17. server: examples.grpc.pb.o examples.pb.o examples_server.o  
18.     $(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@  
19. #chmod 777 $@  
20.   
21. clean:  
22.     sudo rm *.o  

subdir = ./

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

SOURCES = $(wildcard $(subdir)*.cc)
SRCOBJS = $(patsubst %.cc,%.o,$(SOURCES))
CC = g++

%.o:%.cc
	$(CC) -std=c++11 -I/usr/local/include -pthread -c $< -o $@

all: client server

client:	examples.grpc.pb.o examples.pb.o examples_client.o
	$(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@

server:	examples.grpc.pb.o examples.pb.o examples_server.o
	$(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@
#chmod 777 $@

clean:
	sudo rm *.o

六、运行

运行./server启动service，在另一个端口运行./client 打印出：client received: Hello world表示两边已通，grpc+protobuf 搭建完成。