text: // Copyright 2019 DeepMind Technologies Ltd. All rights reserved.
  //
  // Licensed 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.
  
  #ifndef THIRD_PARTY_OPEN_SPIEL_UTILS_BARRIER_H_
  #define THIRD_PARTY_OPEN_SPIEL_UTILS_BARRIER_H_
  
  #include <condition_variable>
  #include <functional>
  #include <mutex>
  #include <thread>
  
  namespace open_spiel {
  
  class Barrier {
   public:
    Barrier(int count);
  
    bool Block(const std::function<void()> &fist_callback = nullptr,
               const std::function<void()> &last_callback = nullptr);
    int Count() { return counter; }
  
   private:
    std::mutex m;
    std::mutex em;
    std::condition_variable cv;
    std::condition_variable ecv;
    bool ok;
    int counter;
    int waiting;
    int thread_count;
  };
  
  }  // namespace open_spiel
  
  #endif  // THIRD_PARTY_OPEN_SPIEL_UTILS_BARRIER_H_
  