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 * modification, are permitted provided that the following conditions are
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 *
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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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#ifndef TEST_QPS_CLIENT_H
#define TEST_QPS_CLIENT_H

#include <condition_variable>
#include <mutex>

#include "test/cpp/qps/histogram.h"
#include "test/cpp/qps/interarrival.h"
#include "test/cpp/qps/timer.h"
#include "test/cpp/qps/qpstest.grpc.pb.h"
#include "test/cpp/util/create_test_channel.h"

namespace grpc {

#if defined(__APPLE__)
// Specialize Timepoint for high res clock as we need that
template <>
class TimePoint<std::chrono::high_resolution_clock::time_point> {
 public:
  TimePoint(const std::chrono::high_resolution_clock::time_point& time) {
    TimepointHR2Timespec(time, &time_);
  }
  gpr_timespec raw_time() const { return time_; }

 private:
  gpr_timespec time_;
};
#endif

namespace testing {

typedef std::chrono::high_resolution_clock grpc_time_source;
typedef std::chrono::time_point<grpc_time_source> grpc_time;

class Client {
 public:
  explicit Client(const ClientConfig& config)
      : channels_(config.client_channels()),
        timer_(new Timer),
        interarrival_timer_() {
    for (int i = 0; i < config.client_channels(); i++) {
      channels_[i].init(config.server_targets(i % config.server_targets_size()),
                        config);
    }
    request_.set_response_type(grpc::testing::PayloadType::COMPRESSABLE);
    request_.set_response_size(config.payload_size());
  }
  virtual ~Client() {}

  ClientStats Mark() {
    Histogram latencies;
    // avoid std::vector for old compilers that expect a copy constructor
    Histogram* to_merge = new Histogram[threads_.size()];
    for (size_t i = 0; i < threads_.size(); i++) {
      threads_[i]->BeginSwap(&to_merge[i]);
    }
    std::unique_ptr<Timer> timer(new Timer);
    timer_.swap(timer);
    for (size_t i = 0; i < threads_.size(); i++) {
      threads_[i]->EndSwap();
      latencies.Merge(&to_merge[i]);
    }
    delete[] to_merge;

    auto timer_result = timer->Mark();

    ClientStats stats;
    latencies.FillProto(stats.mutable_latencies());
    stats.set_time_elapsed(timer_result.wall);
    stats.set_time_system(timer_result.system);
    stats.set_time_user(timer_result.user);
    return stats;
  }

 protected:
  SimpleRequest request_;
  bool closed_loop_;

  class ClientChannelInfo {
   public:
    ClientChannelInfo() {}
    ClientChannelInfo(const ClientChannelInfo& i) {
      // The copy constructor is to satisfy old compilers
      // that need it for using std::vector . It is only ever
      // used for empty entries
      GPR_ASSERT(!i.channel_ && !i.stub_);
    }
    void init(const grpc::string& target, const ClientConfig& config) {
      // We have to use a 2-phase init like this with a default
      // constructor followed by an initializer function to make
      // old compilers happy with using this in std::vector
      channel_ = CreateTestChannel(target, config.enable_ssl());
      stub_ = TestService::NewStub(channel_);
    }
    Channel* get_channel() { return channel_.get(); }
    TestService::Stub* get_stub() { return stub_.get(); }

   private:
    std::shared_ptr<Channel> channel_;
    std::unique_ptr<TestService::Stub> stub_;
  };
  std::vector<ClientChannelInfo> channels_;

  void StartThreads(size_t num_threads) {
    for (size_t i = 0; i < num_threads; i++) {
      threads_.emplace_back(new Thread(this, i));
    }
  }

  void EndThreads() { threads_.clear(); }

  virtual bool ThreadFunc(Histogram* histogram, size_t thread_idx) = 0;

  void SetupLoadTest(const ClientConfig& config, size_t num_threads) {
    // Set up the load distribution based on the number of threads
    if (config.load_type() == CLOSED_LOOP) {
      closed_loop_ = true;
    } else {
      closed_loop_ = false;

      std::unique_ptr<RandomDist> random_dist;
      const 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(
            grpc_time_source::now() +
            std::chrono::duration_cast<grpc_time_source::duration>(
                interarrival_timer_(i)));
      }
    }
  }

  bool NextIssueTime(int thread_idx, grpc_time* time_delay) {
    if (closed_loop_) {
      return false;
    } else {
      *time_delay = next_time_[thread_idx];
      next_time_[thread_idx] +=
          std::chrono::duration_cast<grpc_time_source::duration>(
              interarrival_timer_(thread_idx));
      return true;
    }
  }

 private:
  class Thread {
   public:
    Thread(Client* client, size_t idx)
        : done_(false),
          new_(nullptr),
          client_(client),
          idx_(idx),
          impl_(&Thread::ThreadFunc, this) {}

    ~Thread() {
      {
        std::lock_guard<std::mutex> g(mu_);
        done_ = true;
      }
      impl_.join();
    }

    void BeginSwap(Histogram* n) {
      std::lock_guard<std::mutex> g(mu_);
      new_ = n;
    }

    void EndSwap() {
      std::unique_lock<std::mutex> g(mu_);
      while (new_ != nullptr) {
        cv_.wait(g);
      };
    }

   private:
    Thread(const Thread&);
    Thread& operator=(const Thread&);

    void ThreadFunc() {
      for (;;) {
        // run the loop body
        const bool thread_still_ok = client_->ThreadFunc(&histogram_, idx_);
        // lock, see if we're done
        std::lock_guard<std::mutex> g(mu_);
        if (!thread_still_ok) {
          gpr_log(GPR_ERROR, "Finishing client thread due to RPC error");
          done_ = true;
        }
        if (done_) {
          return;
        }
        // check if we're marking, swap out the histogram if so
        if (new_) {
          new_->Swap(&histogram_);
          new_ = nullptr;
          cv_.notify_one();
        }
      }
    }

    TestService::Stub* stub_;
    ClientConfig config_;
    std::mutex mu_;
    std::condition_variable cv_;
    bool done_;
    Histogram* new_;
    Histogram histogram_;
    Client* client_;
    size_t idx_;
    std::thread impl_;
  };

  std::vector<std::unique_ptr<Thread>> threads_;
  std::unique_ptr<Timer> timer_;

  InterarrivalTimer interarrival_timer_;
  std::vector<grpc_time> next_time_;
};

std::unique_ptr<Client> CreateSynchronousUnaryClient(const ClientConfig& args);
std::unique_ptr<Client> CreateSynchronousStreamingClient(
    const ClientConfig& args);
std::unique_ptr<Client> CreateAsyncUnaryClient(const ClientConfig& args);
std::unique_ptr<Client> CreateAsyncStreamingClient(const ClientConfig& args);

}  // namespace testing
}  // namespace grpc

#endif