queue.h

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#pragma once

#include <queue>

// Mutex and CV cannot be used in managed C++, tell the compiler that this is unmanaged even if included in a managed
// project.
#ifdef _M_CEE
#pragma managed(push, off)
#undef _M_CEE
#include <mutex>
#include <condition_variable>
#define _M_CEE 001
#pragma managed(pop)
#else
#include <mutex>
#include <condition_variable>
#endif

namespace VW
{
template <typename T>
class ptr_queue
{
 public:
  ptr_queue(size_t max_size) : max_size(max_size) {}

  T* pop()
  {
    std::unique_lock<std::mutex> lock(mut);
    while (!done && object_queue.size() == 0)
    {
      is_not_empty.wait(lock);
    }

    if (done && object_queue.size() == 0)
    {
      return nullptr;
    }

    auto item = object_queue.front();
    object_queue.pop();

    lock.unlock();
    is_not_full.notify_all();
    return item;
  }

  void push(T* item)
  {
    std::unique_lock<std::mutex> lock(mut);
    while (object_queue.size() == max_size)
    {
      is_not_full.wait(lock);
    }

    object_queue.push(item);

    lock.unlock();
    is_not_empty.notify_all();
  }

  void set_done()
  {
    done = true;

    is_not_empty.notify_all();
    is_not_full.notify_all();
  }

  size_t size() const { return object_queue.size(); }

 private:
  size_t max_size;
  std::queue<T*> object_queue;
  std::mutex mut;

  bool done = false;

  std::condition_variable is_not_full;
  std::condition_variable is_not_empty;
};
}  // namespace VW