/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <cassert>
#include <functional>
#include <memory>
#include <string>
#include <thread>
#include <vector>
#include <sstream>

#include <grpc/grpc.h>
#include <grpc/support/histogram.h>
#include <grpc/support/log.h>
#include <gflags/gflags.h>
#include <grpc++/async_unary_call.h>
#include <grpc++/client_context.h>
#include <grpc++/status.h>
#include "test/core/util/grpc_profiler.h"
#include "test/cpp/util/create_test_channel.h"
#include "test/cpp/qps/qpstest.pb.h"

DEFINE_bool(enable_ssl, false, "Whether to use ssl/tls.");
DEFINE_int32(server_port, 0, "Server port.");
DEFINE_string(server_host, "127.0.0.1", "Server host.");
DEFINE_int32(client_threads, 4, "Number of client threads.");

// We have a configurable number of channels for sending RPCs.
// RPCs are sent round-robin on the available channels by the
// various threads. Interesting cases are 1 global channel or
// 1 per-thread channel, but we can support any number.
// The channels are assigned round-robin on an RPC by RPC basis
// rather than just at initialization time in order to also measure the
// impact of cache thrashing caused by channel changes. This is an issue
// if you are not in one of the above "interesting cases"
DEFINE_int32(client_channels, 4, "Number of client channels.");

DEFINE_int32(num_rpcs, 1000, "Number of RPCs per thread.");
DEFINE_int32(payload_size, 1, "Payload size in bytes");

// Alternatively, specify parameters for test as a workload so that multiple
// tests are initiated back-to-back. This is convenient for keeping a borg
// allocation consistent. This is a space-separated list of
// [threads channels num_rpcs payload_size ]*
DEFINE_string(workload, "", "Workload parameters");

using grpc::ChannelInterface;
using grpc::CreateTestChannel;
using grpc::testing::ServerStats;
using grpc::testing::SimpleRequest;
using grpc::testing::SimpleResponse;
using grpc::testing::StatsRequest;
using grpc::testing::TestService;

// In some distros, gflags is in the namespace google, and in some others,
// in gflags. This hack is enabling us to find both.
namespace google { }
namespace gflags { }
using namespace google;
using namespace gflags;

static double now() {
  gpr_timespec tv = gpr_now();
  return 1e9 * tv.tv_sec + tv.tv_nsec;
}

  class ClientRpcContext {
  public:
    ClientRpcContext() {}
    virtual ~ClientRpcContext() {}
    virtual bool operator()() = 0; // do next state, return false if steps done
    static void *tag(ClientRpcContext *c) {return reinterpret_cast<void *>(c);}
    static ClientRpcContext *detag(void *t) {
      return reinterpret_cast<ClientRpcContext *>(t);
    }
    virtual void report_stats(gpr_histogram *hist) = 0;
  };
  template <class RequestType, class ResponseType>
    class ClientRpcContextUnaryImpl : public ClientRpcContext {
  public:
    ClientRpcContextUnaryImpl(const RequestType& req,
			      std::function<grpc::ClientAsyncResponseReader<
			      ResponseType> *(grpc::ClientContext *,
					      const RequestType&, void *)> start_req,
			      std::function<void(grpc::Status, ResponseType *)> on_done):
      context_(), req_(req), response_(),	
      next_state_(&ClientRpcContextUnaryImpl::ReqSent),
      callback_(on_done),
      start_(now()),
      response_reader_(start_req(&context_, req_,
				 ClientRpcContext::tag(this))) {
    }
    ~ClientRpcContextUnaryImpl() override {}
    bool operator()() override {return (this->*next_state_)();}
    void report_stats(gpr_histogram *hist) override {
      gpr_histogram_add(hist, now()-start_);
    }
  private:
    bool ReqSent() {
      next_state_ = &ClientRpcContextUnaryImpl::RespDone;
      response_reader_->Finish(&response_, &status_, ClientRpcContext::tag(this));
      return true;
    }
    bool RespDone() {
      next_state_ = &ClientRpcContextUnaryImpl::DoCallBack;
      return false;
    }
    bool DoCallBack() {
      callback_(status_, &response_);
      return false;
    }
    grpc::ClientContext context_;
    RequestType req_;
    ResponseType response_;
    bool (ClientRpcContextUnaryImpl::*next_state_)();
    std::function<void(grpc::Status, ResponseType *)> callback_;
    grpc::Status status_;
    double start_;
    std::unique_ptr<grpc::ClientAsyncResponseReader<ResponseType>> response_reader_;
  };

static void RunTest(const int client_threads, const int client_channels,
		    const int num_rpcs, const int payload_size) {
  gpr_log(GPR_INFO,
          "QPS test with parameters\n"
          "enable_ssl = %d\n"
          "client_channels = %d\n"
          "client_threads = %d\n"
          "num_rpcs = %d\n"
          "payload_size = %d\n"
          "server_host:server_port = %s:%d\n\n",
          FLAGS_enable_ssl, client_channels, client_threads, num_rpcs,
          payload_size, FLAGS_server_host.c_str(), FLAGS_server_port);

  std::ostringstream oss;
  oss << FLAGS_server_host << ":" << FLAGS_server_port;

  class ClientChannelInfo {
   public:
    explicit ClientChannelInfo(const grpc::string &server)
        : channel_(CreateTestChannel(server, FLAGS_enable_ssl)),
          stub_(TestService::NewStub(channel_)) {}
    ChannelInterface *get_channel() { return channel_.get(); }
    TestService::Stub *get_stub() { return stub_.get(); }

   private:
    std::shared_ptr<ChannelInterface> channel_;
    std::unique_ptr<TestService::Stub> stub_;
  };

  std::vector<ClientChannelInfo> channels;
  for (int i = 0; i < client_channels; i++) {
    channels.push_back(ClientChannelInfo(oss.str()));
  }

  std::vector<std::thread> threads;  // Will add threads when ready to execute
  std::vector<::gpr_histogram *> thread_stats(client_threads);

  TestService::Stub *stub_stats = channels[0].get_stub();
  grpc::ClientContext context_stats_begin;
  StatsRequest stats_request;
  ServerStats server_stats_begin;
  stats_request.set_test_num(0);
  grpc::Status status_beg = stub_stats->CollectServerStats(
      &context_stats_begin, stats_request, &server_stats_begin);

  grpc_profiler_start("qps_client_async.prof");

  auto CheckDone = [=](grpc::Status s, SimpleResponse *response) {
    GPR_ASSERT(s.IsOk() &&
	       (response->payload().type() ==
		grpc::testing::PayloadType::COMPRESSABLE) &&
	       (response->payload().body().length() ==
		static_cast<size_t>(payload_size)));
  };
  
  for (int i = 0; i < client_threads; i++) {
    gpr_histogram *hist = gpr_histogram_create(0.01, 60e9);
    GPR_ASSERT(hist != NULL);
    thread_stats[i] = hist;

    threads.push_back(
        std::thread([hist, client_threads, client_channels, num_rpcs,
                     payload_size, &channels, &CheckDone](int channel_num) {
		      using namespace std::placeholders;
                      SimpleRequest request;
                      request.set_response_type(
                          grpc::testing::PayloadType::COMPRESSABLE);
                      request.set_response_size(payload_size);

		      grpc::CompletionQueue cli_cq;

                      int rpcs_sent=0;
                      while (rpcs_sent < num_rpcs) {
                        rpcs_sent++;
                        TestService::Stub *stub =
                            channels[channel_num].get_stub();
                        grpc::ClientContext context;
			auto start_req = std::bind(static_cast<grpc::ClientAsyncResponseReader<SimpleResponse>*(TestService::Stub::*)(grpc::ClientContext *,const SimpleRequest &,grpc::CompletionQueue *,void *)>
						   (&TestService::Stub::UnaryCall),
						   stub, _1, _2, &cli_cq, _3);
			new ClientRpcContextUnaryImpl<SimpleRequest,
						      SimpleResponse>(request,
								      start_req,
								      CheckDone);
			void *got_tag;
			bool ok;

			// Need to call 2 next for every 1 RPC (1 for req done, 1 for resp done)
			cli_cq.Next(&got_tag,&ok);
			if (!ok)
			  break;
			ClientRpcContext *ctx = ClientRpcContext::detag(got_tag);
			if ((*ctx)() == false) {
			  // call the callback and then delete it
			  (*ctx)();
			  delete ctx;
			}
			cli_cq.Next(&got_tag,&ok);
			if (!ok)
			  break;
			ctx = ClientRpcContext::detag(got_tag);
			if ((*ctx)() == false) {
			  // call the callback and then delete it
			  ctx->report_stats(hist);
			  (*ctx)();
			  delete ctx;
			}
			// Now do runtime round-robin assignment of the next
			// channel number
			channel_num += client_threads;
			channel_num %= client_channels;
		      }
                    },
                    i % client_channels));
  }

  gpr_histogram *hist = gpr_histogram_create(0.01, 60e9);
  GPR_ASSERT(hist != NULL);
  for (auto &t : threads) {
    t.join();
  }

  grpc_profiler_stop();

  for (int i = 0; i < client_threads; i++) {
    gpr_histogram *h = thread_stats[i];
    gpr_log(GPR_INFO, "latency at thread %d (50/90/95/99/99.9): %f/%f/%f/%f/%f",
            i, gpr_histogram_percentile(h, 50), gpr_histogram_percentile(h, 90),
            gpr_histogram_percentile(h, 95), gpr_histogram_percentile(h, 99),
            gpr_histogram_percentile(h, 99.9));
    gpr_histogram_merge(hist, h);
    gpr_histogram_destroy(h);
  }

  gpr_log(
      GPR_INFO,
      "latency across %d threads with %d channels and %d payload "
      "(50/90/95/99/99.9): %f / %f / %f / %f / %f",
      client_threads, client_channels, payload_size,
      gpr_histogram_percentile(hist, 50), gpr_histogram_percentile(hist, 90),
      gpr_histogram_percentile(hist, 95), gpr_histogram_percentile(hist, 99),
      gpr_histogram_percentile(hist, 99.9));
  gpr_histogram_destroy(hist);

  grpc::ClientContext context_stats_end;
  ServerStats server_stats_end;
  grpc::Status status_end = stub_stats->CollectServerStats(
      &context_stats_end, stats_request, &server_stats_end);

  double elapsed = server_stats_end.time_now() - server_stats_begin.time_now();
  int total_rpcs = client_threads * num_rpcs;
  double utime = server_stats_end.time_user() - server_stats_begin.time_user();
  double stime =
      server_stats_end.time_system() - server_stats_begin.time_system();
  gpr_log(GPR_INFO,
          "Elapsed time: %.3f\n"
          "RPC Count: %d\n"
          "QPS: %.3f\n"
          "System time: %.3f\n"
          "User time: %.3f\n"
          "Resource usage: %.1f%%\n",
          elapsed, total_rpcs, total_rpcs / elapsed, stime, utime,
          (stime + utime) / elapsed * 100.0);
}

int main(int argc, char **argv) {
  grpc_init();
  ParseCommandLineFlags(&argc, &argv, true);

  GPR_ASSERT(FLAGS_server_port);

  if (FLAGS_workload.length() == 0) {
    RunTest(FLAGS_client_threads, FLAGS_client_channels, FLAGS_num_rpcs,
            FLAGS_payload_size);
  } else {
    std::istringstream workload(FLAGS_workload);
    int client_threads, client_channels, num_rpcs, payload_size;
    workload >> client_threads;
    while (!workload.eof()) {
      workload >> client_channels >> num_rpcs >> payload_size;
      RunTest(client_threads, client_channels, num_rpcs, payload_size);
      workload >> client_threads;
    }
    gpr_log(GPR_INFO, "Done with specified workload.");
  }

  grpc_shutdown();
  return 0;
}