UnlikelyLock.h

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/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#ifndef UNLIKELY_LOCK_H
#define UNLIKELY_LOCK_H
 
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/process/ConditionVariable.h"
#include "pedigree/kernel/process/Mutex.h"
#include "pedigree/kernel/processor/types.h"
 
#define UNLIKELY_LOCK_MAX_READERS 9999
 
class EXPORTED_PUBLIC UnlikelyLock {
 public:
  UnlikelyLock();
  ~UnlikelyLock();
 
  void enter();
 
  void leave();
 
  void acquire();
 
  void release();
 
 private:
  Mutex m_Lock;
  ConditionVariable m_Condition;
 
  uint64_t m_nReaders;
  uint64_t m_nWaitingWriters;
  bool m_bActiveWriter;
};
 
#endif