// 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 sleeping for even-th requests to trigger backup request of client.

#include <gflags/gflags.h>
#include <butil/logging.h>
#include <brpc/server.h>
#include "echo.pb.h"

DEFINE_bool(echo_attachment, true, "Echo attachment as well");
DEFINE_int32(port, 8000, "TCP Port of this server");
DEFINE_int32(idle_timeout_s, -1, "Connection will be closed if there is no "
             "read/write operations during the last `idle_timeout_s'");
DEFINE_int32(sleep_ms, 20, "Sleep so many milliseconds on even-th requests");

// Your implementation of example::EchoService
// Notice that implementing brpc::Describable grants the ability to put
// additional information in /status.
namespace example {
class SleepyEchoService : public EchoService
                        , public brpc::Describable {
public:
    SleepyEchoService() : _count(0) {}
    virtual ~SleepyEchoService() {}
    virtual void Echo(google::protobuf::RpcController* cntl_base,
                      const EchoRequest* request,
                      EchoResponse* response,
                      google::protobuf::Closure* done) {
        // This object helps you to call done->Run() in RAII style. If you need
        // to process the request asynchronously, pass done_guard.release().
        brpc::ClosureGuard done_guard(done);

        brpc::Controller* cntl =
            static_cast<brpc::Controller*>(cntl_base);

        // The purpose of following logs is to help you to understand
        // how clients interact with servers more intuitively. You should 
        // remove these logs in performance-sensitive servers.
        // The noflush prevents the log from being flushed immediately.
        LOG(INFO) << "Received request[index=" << request->index()
                  << "] from " << cntl->remote_side() 
                  << " to " << cntl->local_side() << noflush;
        // Sleep a while for 0th, 2nd, 4th, 6th ... requests to trigger backup request
        // at client-side.
        bool do_sleep = (_count.fetch_add(1, butil::memory_order_relaxed) % 2 == 0);
        if (do_sleep) {
            LOG(INFO) << ", sleep " << FLAGS_sleep_ms 
                      << " ms to trigger backup request" << noflush;
        }
        LOG(INFO);

        // Fill response.
        response->set_index(request->index());

        if (do_sleep) {
            bthread_usleep(FLAGS_sleep_ms * 1000);
        }
    }
private:
    butil::atomic<int> _count;
};
}  // namespace example

int main(int argc, char* argv[]) {
    // Parse gflags. We recommend you to use gflags as well.
    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);

    // Generally you only need one Server.
    brpc::Server server;

    // Instance of your service.
    example::SleepyEchoService 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.idle_timeout_sec = FLAGS_idle_timeout_s;
    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;
}