pool.h

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#ifndef HEDGEHOG_POOL_H
#define HEDGEHOG_POOL_H

#include <memory>
#include <deque>
#include <algorithm>
#include <cassert>
#include <mutex>
#include <condition_variable>

namespace hh::behavior {

template<class ManagedData>
class Pool {
 private:
  size_t capacity_ = 1; 
  std::deque<std::shared_ptr<ManagedData>> queue_ = {}; 
  std::mutex mutex_ = {}; 
  std::unique_ptr<std::condition_variable>
      conditionVariable_ = std::make_unique<std::condition_variable>(); 

 public:
  explicit Pool(size_t const &capacity) {
    capacity_ = capacity == 0 ? 1 : capacity;
    queue_ = std::deque<std::shared_ptr<ManagedData>>(capacity_);
  }

  std::deque<std::shared_ptr<ManagedData>> const &queue() const { return queue_; }

  typename std::deque<std::shared_ptr<ManagedData>>::iterator begin() { return this->queue_.begin(); }

  typename std::deque<std::shared_ptr<ManagedData>>::iterator end() { return this->queue_.end(); }

  size_t size() {
    std::lock_guard<std::mutex> lock(mutex_);
    return queue_.size();
  }

  bool empty() { return queue_.empty(); }

  [[nodiscard]] size_t capacity() const { return capacity_; }

  void push_back(std::shared_ptr<ManagedData> const &data) {
    std::lock_guard<std::mutex> lock(mutex_);
    this->queue_.push_back(data);
    if (this->queue_.size() > capacity_) {
      std::ostringstream oss;
      oss << "The queue is overflowing, the same data " << data << " has been returned to the memory manager too many "
          << "times: "
          << __FUNCTION__;
      HLOG_SELF(0, oss.str())
      throw (std::runtime_error(oss.str()));
    }
    conditionVariable_->notify_one();
  }

  std::shared_ptr<ManagedData> pop_front() {
    std::unique_lock<std::mutex> lock(mutex_);
    std::shared_ptr<ManagedData> ret = nullptr;
    // Wait if the queue is empty
    conditionVariable_->wait(lock, [this]() { return !queue_.empty(); });
    ret = queue_.front();
    queue_.pop_front();
    conditionVariable_->notify_one();
    return ret;
  }

};
}

#endif //HEDGEHOG_POOL_H