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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#include <cassert>
#include <chrono>
#include <memory>
#include <mutex>
#include <string>
#include <thread>
#include <vector>
#include <sstream>

#include <sys/signal.h>

#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/histogram.h>
#include <grpc/support/log.h>
#include <grpc/support/host_port.h>
#include <gflags/gflags.h>
#include <grpc++/client_context.h>
#include <grpc++/server.h>
#include <grpc++/server_builder.h>
#include <grpc++/status.h>
#include <grpc++/stream.h>
#include <gtest/gtest.h>
#include "test/cpp/util/create_test_channel.h"
#include "test/cpp/qps/client.h"
#include "test/cpp/qps/qpstest.grpc.pb.h"
#include "test/cpp/qps/histogram.h"
#include "test/cpp/qps/interarrival.h"
#include "test/cpp/qps/timer.h"

namespace grpc {
namespace testing {

class SynchronousClient : public Client {
 public:
  SynchronousClient(const ClientConfig& config) : Client(config),
                                                  interarrival_timer_() {
    num_threads_ =
      config.outstanding_rpcs_per_channel() * config.client_channels();
    responses_.resize(num_threads_);

    // Now sort out the load test type
    if (config.load_type() == CLOSED_LOOP) {
      closed_loop_ = true;
    }
    else {
      closed_loop_ = false;

      std::unique_ptr<RandomDist> random_dist;
      auto& load = config.load_params();
      switch (config.load_type()) {
        case POISSON:
          random_dist.reset
              (new ExpDist(load.poisson().offered_load()/num_threads_));
          break;
        case UNIFORM:
          random_dist.reset
              (new UniformDist(load.uniform().interarrival_lo()*num_threads_,
                               load.uniform().interarrival_hi()*num_threads_));
          break;
        case DETERMINISTIC:
          random_dist.reset
              (new DetDist(num_threads_/load.determ().offered_load()));
          break;
        case PARETO:
          random_dist.reset
              (new ParetoDist(load.pareto().interarrival_base()*num_threads_,
                              load.pareto().alpha()));
          break;
        default:
          GPR_ASSERT(false);
          break;
      }

      interarrival_timer_.init(*random_dist, num_threads_);
      for (size_t i = 0; i<num_threads_; i++) {
        next_time_.push_back(std::chrono::high_resolution_clock::now()
                             + interarrival_timer_(i));
      }
    }
  }

  virtual ~SynchronousClient() { EndThreads(); }

 protected:
  void WaitToIssue(int thread_idx) {
    if (!closed_loop_) {
      std::this_thread::sleep_until(next_time_[thread_idx]);
      next_time_[thread_idx] += interarrival_timer_(thread_idx);
    }
  }

  size_t num_threads_;
  std::vector<SimpleResponse> responses_;
 private:
  bool closed_loop_;
  InterarrivalTimer interarrival_timer_;
  std::vector<std::chrono::time_point
             <std::chrono::high_resolution_clock>> next_time_;
};

class SynchronousUnaryClient GRPC_FINAL : public SynchronousClient {
 public:
  SynchronousUnaryClient(const ClientConfig& config):
    SynchronousClient(config) {StartThreads(num_threads_);}
  ~SynchronousUnaryClient() {}

  bool ThreadFunc(Histogram* histogram, size_t thread_idx) GRPC_OVERRIDE {
    WaitToIssue(thread_idx);
    auto* stub = channels_[thread_idx % channels_.size()].get_stub();
    double start = Timer::Now();
    grpc::ClientContext context;
    grpc::Status s =
        stub->UnaryCall(&context, request_, &responses_[thread_idx]);
    histogram->Add((Timer::Now() - start) * 1e9);
    return s.IsOk();
  }
};

class SynchronousStreamingClient GRPC_FINAL : public SynchronousClient {
 public:
  SynchronousStreamingClient(const ClientConfig& config):
    SynchronousClient(config) {
    for (size_t thread_idx=0;thread_idx<num_threads_;thread_idx++){
      auto* stub = channels_[thread_idx % channels_.size()].get_stub();
      stream_ = stub->StreamingCall(&context_);
    }
    StartThreads(num_threads_);
  }
  ~SynchronousStreamingClient() {
    EndThreads();
    if (stream_) {
      SimpleResponse response;
      stream_->WritesDone();
      EXPECT_TRUE(stream_->Finish().IsOk());
    }
  }

  bool ThreadFunc(Histogram* histogram, size_t thread_idx) GRPC_OVERRIDE {
    WaitToIssue(thread_idx);
    double start = Timer::Now();
    if (stream_->Write(request_) && stream_->Read(&responses_[thread_idx])) {
      histogram->Add((Timer::Now() - start) * 1e9);
      return true;
    }
    return false;
  }
  private:
    grpc::ClientContext context_;
    std::unique_ptr<grpc::ClientReaderWriter<SimpleRequest,
                                             SimpleResponse>> stream_;
};

std::unique_ptr<Client>
CreateSynchronousUnaryClient(const ClientConfig& config) {
  return std::unique_ptr<Client>(new SynchronousUnaryClient(config));
}
std::unique_ptr<Client>
CreateSynchronousStreamingClient(const ClientConfig& config) {
  return std::unique_ptr<Client>(new SynchronousStreamingClient(config));
}

}  // namespace testing
}  // namespace grpc