1 /*
2 *
3 * Copyright 2024 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 #include <condition_variable>
20 #include <iostream>
21 #include <memory>
22 #include <mutex>
23 #include <string>
24
25 #include "absl/flags/flag.h"
26 #include "absl/flags/parse.h"
27
28 #include <grpcpp/grpcpp.h>
29
30 #ifdef BAZEL_BUILD
31 #include "examples/protos/helloworld.grpc.pb.h"
32
33 #include "src/proto/grpc/health/v1/health.grpc.pb.h"
34 #else
35 #include "health.grpc.pb.h"
36 #include "helloworld.grpc.pb.h"
37 #endif
38
39 ABSL_FLAG(std::string, target, "localhost:50051", "Server address");
40
41 using grpc::Channel;
42 using grpc::ClientContext;
43 using grpc::Status;
44 using grpc::health::v1::Health;
45 using grpc::health::v1::HealthCheckRequest;
46 using grpc::health::v1::HealthCheckResponse;
47 using helloworld::Greeter;
48 using helloworld::HelloReply;
49 using helloworld::HelloRequest;
50
51 class GreeterClient {
52 public:
GreeterClient(std::shared_ptr<Channel> channel)53 GreeterClient(std::shared_ptr<Channel> channel)
54 : stub_(Greeter::NewStub(channel)),
55 health_stub_(Health::NewStub(channel)) {}
56
57 // Assembles the client's payload, sends it and presents the response back
58 // from the server.
SayHello(const std::string & user)59 std::string SayHello(const std::string& user) {
60 // Data we are sending to the server.
61 HelloRequest request;
62 request.set_name(user);
63
64 // Container for the data we expect from the server.
65 HelloReply reply;
66
67 // Context for the client. It could be used to convey extra information to
68 // the server and/or tweak certain RPC behaviors.
69 ClientContext context;
70
71 // The actual RPC.
72 std::mutex mu;
73 std::condition_variable cv;
74 bool done = false;
75 Status status;
76 stub_->async()->SayHello(&context, &request, &reply,
77 [&mu, &cv, &done, &status](Status s) {
78 status = std::move(s);
79 std::lock_guard<std::mutex> lock(mu);
80 done = true;
81 cv.notify_one();
82 });
83
84 std::unique_lock<std::mutex> lock(mu);
85 while (!done) {
86 cv.wait(lock);
87 }
88
89 // Act upon its status.
90 if (status.ok()) {
91 return reply.message();
92 } else {
93 std::cout << status.error_code() << ": " << status.error_message()
94 << std::endl;
95 return "RPC failed";
96 }
97 }
98
CheckHealth(const std::string & message)99 void CheckHealth(const std::string& message) {
100 ClientContext context;
101 HealthCheckResponse response;
102 Status status = health_stub_->Check(
103 &context, HealthCheckRequest::default_instance(), &response);
104 if (!status.ok()) {
105 std::cerr << "Failed to check service health: " << status.error_code()
106 << ": " << status.error_message() << "\n";
107 return;
108 }
109 std::cout << message << ": " << response.DebugString();
110 }
111
112 private:
113 std::unique_ptr<Greeter::Stub> stub_;
114 std::unique_ptr<Health::Stub> health_stub_;
115 };
116
main(int argc,char ** argv)117 int main(int argc, char** argv) {
118 absl::ParseCommandLine(argc, argv);
119 // Instantiate the client. It requires a channel, out of which the actual RPCs
120 // are created. This channel models a connection to an endpoint specified by
121 // the argument "--target=" which is the only expected argument.
122 std::string target_str = absl::GetFlag(FLAGS_target);
123 // We indicate that the channel isn't authenticated (use of
124 // InsecureChannelCredentials()).
125 grpc::ChannelArguments args;
126 args.SetServiceConfigJSON(
127 "{\"healthCheckConfig\": "
128 "{\"serviceName\": \"\"}}");
129 GreeterClient greeter(grpc::CreateCustomChannel(
130 target_str, grpc::InsecureChannelCredentials(), args));
131 std::string user = "world";
132 greeter.CheckHealth("Before call");
133 std::string reply = greeter.SayHello(user);
134 std::cout << "Greeter received: " << reply << std::endl;
135 greeter.CheckHealth("After call");
136 reply = greeter.SayHello(user);
137 std::cout << "Greeter received: " << reply << std::endl;
138 greeter.CheckHealth("After second call");
139 return 0;
140 }
141