OperationBarrier.h

/*
 * Copyright (c) 2026, Pedigree Developers
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted.
 */
 
#ifndef PEDIGREE_KERNEL_PROCESS_OPERATIONBARRIER_H
#define PEDIGREE_KERNEL_PROCESS_OPERATIONBARRIER_H
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/process/WaitQueue.h"
 
#include <config.h>
 
class EXPORTED_PUBLIC OperationBarrier {
 public:
  class EXPORTED_PUBLIC Lease {
   public:
    Lease();
    Lease(Lease&& other) noexcept;
    ~Lease();
 
    Lease& operator=(Lease&& other) noexcept;
 
    explicit operator bool() const {
      return m_Barrier != nullptr;
    }
 
   private:
    friend class OperationBarrier;
 
    explicit Lease(OperationBarrier* barrier);
    void reset();
 
    Lease(const Lease&) = delete;
    Lease& operator=(const Lease&) = delete;
 
    OperationBarrier* m_Barrier;
  };
 
  OperationBarrier();
  ~OperationBarrier();
 
  MUST_USE_RESULT bool tryEnter();
 
  MUST_USE_RESULT bool tryAcquire(Lease& lease);
 
  void leave();
 
  void close();
 
  MUST_USE_RESULT bool tryCloseIfIdle();
 
  void wait();
 
  void closeAndWait();
 
  bool isOpen();
  bool isClosedAndDrained();
 
 private:
  NOT_COPYABLE_OR_ASSIGNABLE(OperationBarrier);
 
  static constexpr size_t Closed = size_t{1} << (sizeof(size_t) * 8 - 1);
  static constexpr size_t CountMask = Closed - 1;
  static_assert(__atomic_always_lock_free(sizeof(size_t), nullptr));
 
  WaitQueue m_Waiters;
  size_t m_State;
};
 
#endif