chore: import upstream snapshot with attribution

example/coroutine/coroutine_server.cpp

@@ -0,0 +1,145 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// A server to receive EchoRequest and send back EchoResponse.
+
+#include <gflags/gflags.h>
+#include <butil/logging.h>
+#include <brpc/server.h>
+#include <brpc/channel.h>
+#include <brpc/coroutine.h>
+#include "echo.pb.h"
+
+DEFINE_int32(port, 8000, "TCP Port of this server");
+DEFINE_int32(sleep_us, 1000000, "Server sleep us");
+DEFINE_bool(enable_coroutine, true, "Enable coroutine");
+
+using brpc::experimental::Awaitable;
+using brpc::experimental::AwaitableDone;
+using brpc::experimental::Coroutine;
+
+namespace example {
+class EchoServiceImpl : public EchoService {
+public:
+    EchoServiceImpl() {
+        brpc::ChannelOptions options;
+        options.timeout_ms = FLAGS_sleep_us / 1000 * 2 + 100;
+        options.max_retry = 0;
+        CHECK(_channel.Init(butil::EndPoint(butil::IP_ANY, FLAGS_port), &options) == 0);
+    }
+
+    virtual ~EchoServiceImpl() {}
+
+    void Echo(google::protobuf::RpcController* cntl_base,
+              const EchoRequest* request,
+              EchoResponse* response,
+              google::protobuf::Closure* done) override {
+        // brpc::Controller* cntl =
+        //     static_cast<brpc::Controller*>(cntl_base);
+
+        if (FLAGS_enable_coroutine) {
+            Coroutine(EchoAsync(request, response, done), true);
+        } else {
+            brpc::ClosureGuard done_guard(done);
+            bthread_usleep(FLAGS_sleep_us);
+            response->set_message(request->message());
+        }
+    }
+
+    Awaitable<void> EchoAsync(const EchoRequest* request,
+               EchoResponse* response,
+               google::protobuf::Closure* done) {
+        brpc::ClosureGuard done_guard(done);
+        co_await Coroutine::usleep(FLAGS_sleep_us);
+        response->set_message(request->message());
+    }
+
+    void Proxy(google::protobuf::RpcController* cntl_base,
+               const EchoRequest* request,
+               EchoResponse* response,
+               google::protobuf::Closure* done) override {
+        // brpc::Controller* cntl =
+        //     static_cast<brpc::Controller*>(cntl_base);
+
+        if (FLAGS_enable_coroutine) {
+            Coroutine(ProxyAsync(request, response, done), true);
+        } else {
+            brpc::ClosureGuard done_guard(done);
+            EchoService_Stub stub(&_channel);
+            brpc::Controller cntl;
+            stub.Echo(&cntl, request, response, NULL);
+            if (cntl.Failed()) {
+                response->set_message(cntl.ErrorText());
+            }
+        }
+    }
+
+    Awaitable<void> ProxyAsync(const EchoRequest* request,
+                    EchoResponse* response,
+                    google::protobuf::Closure* done) {
+        brpc::ClosureGuard done_guard(done);
+        EchoService_Stub stub(&_channel);
+        brpc::Controller cntl;
+        AwaitableDone done2;
+        stub.Echo(&cntl, request, response, &done2);
+        co_await done2.awaitable();
+        if (cntl.Failed()) {
+            response->set_message(cntl.ErrorText());
+        }
+    }    
+
+private:
+    brpc::Channel _channel;
+};
+}  // namespace example
+
+int main(int argc, char* argv[]) {
+    bthread_setconcurrency(BTHREAD_MIN_CONCURRENCY);
+
+    // Parse gflags. We recommend you to use gflags as well.
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
+    if (FLAGS_enable_coroutine) {
+        GFLAGS_NAMESPACE::SetCommandLineOption("usercode_in_coroutine", "true");
+    }
+
+    // Generally you only need one Server.
+    brpc::Server server;
+
+    // Instance of your service.
+    example::EchoServiceImpl echo_service_impl;
+
+    // Add the service into server. Notice the second parameter, because the
+    // service is put on stack, we don't want server to delete it, otherwise
+    // use brpc::SERVER_OWNS_SERVICE.
+    if (server.AddService(&echo_service_impl, 
+                          brpc::SERVER_DOESNT_OWN_SERVICE) != 0) {
+        LOG(ERROR) << "Fail to add service";
+        return -1;
+    }
+
+    // Start the server.
+    brpc::ServerOptions options;
+    options.num_threads = BTHREAD_MIN_CONCURRENCY;
+    if (server.Start(FLAGS_port, &options) != 0) {
+        LOG(ERROR) << "Fail to start EchoServer";
+        return -1;
+    }
+
+    // Wait until Ctrl-C is pressed, then Stop() and Join() the server.
+    server.RunUntilAskedToQuit();
+    return 0;
+}