[Example] Update route_guide example (#36930)

The intention behind this PR is to improve the example to aid the upcoming callback API guide.

Also fixes #25823

Closes #36930

PiperOrigin-RevId: 644166441

examples/cpp/route_guide/BUILD

@@ -24,6 +24,7 @@ cc_library(
     deps = [
         "//:grpc++",
         "//examples/protos:route_guide",
+        "@com_google_absl//absl/log",
     ],
 )
 
@@ -80,5 +81,9 @@ cc_binary(
         ":route_guide_helper",
         "//:grpc++",
         "//examples/protos:route_guide",
+        "@com_google_absl//absl/flags:parse",
+        "@com_google_absl//absl/log",
+        "@com_google_absl//absl/log:globals",
+        "@com_google_absl//absl/log:initialize",
     ],
 )

examples/cpp/route_guide/CMakeLists.txt

@@ -23,6 +23,9 @@ project(RouteGuide C CXX)
 
 include(../cmake/common.cmake)
 
+# Find absl package
+find_package(absl CONFIG REQUIRED)
+
 # Proto file
 get_filename_component(rg_proto "../../protos/route_guide.proto" ABSOLUTE)
 get_filename_component(rg_proto_path "${rg_proto}" PATH)
@@ -52,6 +55,7 @@ add_library(rg_grpc_proto
   ${rg_proto_srcs}
   ${rg_proto_hdrs})
 target_link_libraries(rg_grpc_proto
+  absl::absl_log
   ${_REFLECTION}
   ${_GRPC_GRPCPP}
   ${_PROTOBUF_LIBPROTOBUF})
@@ -74,6 +78,10 @@ foreach(_target
   target_link_libraries(${_target}
     rg_grpc_proto
     route_guide_helper
+    absl::flags_parse
+    absl::absl_log
+    absl::log_initialize
+    absl::log_globals
     ${_REFLECTION}
     ${_GRPC_GRPCPP}
     ${_PROTOBUF_LIBPROTOBUF})

examples/cpp/route_guide/Makefile

@@ -30,6 +30,7 @@ CXXFLAGS += -std=c++14
 ifeq ($(SYSTEM),Darwin)
 LDFLAGS += -L/usr/local/lib `pkg-config --libs --static protobuf grpc++ $(PROTOBUF_ABSL_DEPS)`\
            $(PROTOBUF_UTF8_RANGE_LINK_LIBS) \
+		   -labsl_flags_parse -labsl_absl_log -labsl_log_globals -labsl_log_initialize
            -pthread\
            -lgrpc++_reflection\
            -ldl

examples/cpp/route_guide/README.md

@@ -4,3 +4,23 @@ The files in this folder are the samples used in [gRPC Basics: C++][],
 a detailed tutorial for using gRPC in C++.
 
 [gRPC Basics: C++]:https://grpc.io/docs/languages/cpp/basics
+
+## Configuration
+
+The RouteGuide proto definition is available [here](../../protos/route_guide.proto).
+The server takes the following command-line argument -
+* db_path - Path to json file containing database. Defaults to `examples/cpp/route_guide/route_guide_db.json` on bazel builds, and `route_guide_db.json` for non-bazel builds.
+
+## Running the example
+
+To run the server -
+
+```
+$ tools/bazel run examples/cpp/route_guide:route_guide_callback_server
+```
+
+To run the client -
+
+```
+$ tools/bazel run examples/cpp/route_guide:route_guide_callback_client
+```

examples/cpp/route_guide/helper.cc

@@ -23,36 +23,30 @@
 #include <sstream>
 #include <string>
 #include <vector>
+
+#include "absl/flags/flag.h"
+#include "absl/log/log.h"
+
 #ifdef BAZEL_BUILD
 #include "examples/protos/route_guide.grpc.pb.h"
 #else
 #include "route_guide.grpc.pb.h"
 #endif
 
-namespace routeguide {
-
-std::string GetDbFileContent(int argc, char** argv) {
-  std::string db_path;
-  std::string arg_str("--db_path");
-  if (argc > 1) {
-    std::string argv_1 = argv[1];
-    size_t start_position = argv_1.find(arg_str);
-    if (start_position != std::string::npos) {
-      start_position += arg_str.size();
-      if (argv_1[start_position] == ' ' || argv_1[start_position] == '=') {
-        db_path = argv_1.substr(start_position + 1);
-      }
-    }
-  } else {
 #ifdef BAZEL_BUILD
-    db_path = "cpp/route_guide/route_guide_db.json";
+ABSL_FLAG(std::string, db_path, "examples/cpp/route_guide/route_guide_db.json",
+          "Path to db file");
 #else
-    db_path = "route_guide_db.json";
+ABSL_FLAG(std::string, db_path, "route_guide_db.json", "Path to db file");
 #endif
-  }
+
+namespace routeguide {
+
+std::string GetDbFileContent(int argc, char** argv) {
+  std::string db_path = absl::GetFlag(FLAGS_db_path);
   std::ifstream db_file(db_path);
   if (!db_file.is_open()) {
-    std::cout << "Failed to open " << db_path << std::endl;
+    LOG(ERROR) << "Failed to open " << db_path;
     abort();
   }
   std::stringstream db;
@@ -152,13 +146,12 @@ void ParseDb(const std::string& db, std::vector<Feature>* feature_list) {
   while (!parser.Finished()) {
     feature_list->push_back(Feature());
     if (!parser.TryParseOne(&feature_list->back())) {
-      std::cout << "Error parsing the db file";
+      LOG(ERROR) << "Error parsing the db file";
       feature_list->clear();
       break;
     }
   }
-  std::cout << "DB parsed, loaded " << feature_list->size() << " features."
-            << std::endl;
+  LOG(INFO) << "DB parsed, loaded " << feature_list->size() << " features.";
 }
 
 }  // namespace routeguide

examples/cpp/route_guide/route_guide_callback_server.cc

@@ -24,6 +24,10 @@
 #include <string>
 #include <thread>
 
+#include "absl/flags/parse.h"
+#include "absl/log/globals.h"
+#include "absl/log/initialize.h"
+#include "absl/log/log.h"
 #include "helper.h"
 
 #include <grpc/grpc.h>
@@ -88,6 +92,30 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
     routeguide::ParseDb(db, &feature_list_);
   }
 
+  grpc::ServerUnaryReactor* GetFeature(grpc::CallbackServerContext* context,
+                                       const Point* point,
+                                       Feature* feature) override {
+    class Reactor : public grpc::ServerUnaryReactor {
+     public:
+      Reactor(const Point& point, const std::vector<Feature>& feature_list,
+              Feature* feature) {
+        feature->set_name(GetFeatureName(point, feature_list));
+        *feature->mutable_location() = point;
+        Finish(grpc::Status::OK);
+      }
+
+     private:
+      void OnDone() override {
+        LOG(INFO) << "RPC Completed";
+        delete this;
+      }
+
+      void OnCancel() override { LOG(ERROR) << "RPC Cancelled"; }
+    };
+    return new Reactor(*point, feature_list_, feature);
+  }
+
+  /* Alternate simple implementation of GetFeature that uses the DefaultReactor.
   grpc::ServerUnaryReactor* GetFeature(CallbackServerContext* context,
                                        const Point* point,
                                        Feature* feature) override {
@@ -97,6 +125,7 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
     reactor->Finish(Status::OK);
     return reactor;
   }
+*/
 
   grpc::ServerWriteReactor<Feature>* ListFeatures(
       CallbackServerContext* context,
@@ -117,8 +146,20 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
             next_feature_(feature_list_->begin()) {
         NextWrite();
       }
-      void OnDone() override { delete this; }
-      void OnWriteDone(bool /*ok*/) override { NextWrite(); }
+
+      void OnWriteDone(bool ok) override {
+        if (!ok) {
+          Finish(Status(grpc::StatusCode::UNKNOWN, "Unexpected Failure"));
+        }
+        NextWrite();
+      }
+
+      void OnDone() override {
+        LOG(INFO) << "RPC Completed";
+        delete this;
+      }
+
+      void OnCancel() override { LOG(ERROR) << "RPC Cancelled"; }
 
      private:
       void NextWrite() {
@@ -156,7 +197,7 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
             feature_list_(feature_list) {
         StartRead(&point_);
       }
-      void OnDone() override { delete this; }
+
       void OnReadDone(bool ok) override {
         if (ok) {
           point_count_++;
@@ -179,6 +220,13 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
         }
       }
 
+      void OnDone() override {
+        LOG(INFO) << "RPC Completed";
+        delete this;
+      }
+
+      void OnCancel() override { LOG(ERROR) << "RPC Cancelled"; }
+
      private:
       system_clock::time_point start_time_;
       RouteSummary* summary_;
@@ -200,7 +248,7 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
           : mu_(mu), received_notes_(received_notes) {
         StartRead(&note_);
       }
-      void OnDone() override { delete this; }
+
       void OnReadDone(bool ok) override {
         if (ok) {
           // Unlike the other example in this directory that's not using
@@ -228,6 +276,13 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
       }
       void OnWriteDone(bool /*ok*/) override { NextWrite(); }
 
+      void OnDone() override {
+        LOG(INFO) << "RPC Completed";
+        delete this;
+      }
+
+      void OnCancel() override { LOG(ERROR) << "RPC Cancelled"; }
+
      private:
       void NextWrite() {
         if (notes_iterator_ != to_send_notes_.end()) {
@@ -240,9 +295,10 @@ class RouteGuideImpl final : public RouteGuide::CallbackService {
           StartRead(&note_);
         }
       }
+
       RouteNote note_;
       absl::Mutex* mu_;
-      std::vector<RouteNote>* received_notes_;
+      std::vector<RouteNote>* received_notes_ ABSL_GUARDED_BY(mu_);
       std::vector<RouteNote> to_send_notes_;
       std::vector<RouteNote>::iterator notes_iterator_;
     };
@@ -263,11 +319,14 @@ void RunServer(const std::string& db_path) {
   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;
+  LOG(INFO) << "Server listening on " << server_address;
   server->Wait();
 }
 
 int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
+  absl::SetStderrThreshold(absl::LogSeverityAtLeast::kInfo);
+  absl::InitializeLog();
   // Expect only arg: --db_path=path/to/route_guide_db.json.
   std::string db = routeguide::GetDbFileContent(argc, argv);
   RunServer(db);