Semaphore.h

/*
 * 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 SEMAPHORE_H
#define SEMAPHORE_H

#include "pedigree/kernel/Atomic.h"
#include "pedigree/kernel/Spinlock.h"
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/process/Event.h"
#include "pedigree/kernel/processor/types.h"
#include "pedigree/kernel/utilities/List.h"
#include "pedigree/kernel/utilities/Result.h"
#include "pedigree/kernel/utilities/new"

class EXPORTED_PUBLIC Semaphore
{
  public:
    enum SemaphoreError
    {
        TimedOut,
        Interrupted,
    };
    typedef Result<bool, SemaphoreError> SemaphoreResult;
    Semaphore(size_t nInitialValue, bool canInterrupt = true);
    virtual ~Semaphore();

    SemaphoreResult acquireWithResult(
        size_t n = 1, size_t timeoutSecs = 0, size_t timeoutUsecs = 0);

    bool acquire(size_t n = 1, size_t timeoutSecs = 0, size_t timeoutUsecs = 0)
    {
        SemaphoreResult result =
            acquireWithResult(n, timeoutSecs, timeoutUsecs);
        if (result.hasValue())
        {
            return result.value();
        }
        else
        {
            return false;
        }
    }

    bool tryAcquire(size_t n = 1);

    void release(size_t n = 1);

    ssize_t getValue();

  private:
    Semaphore(const Semaphore &);
    void operator=(const Semaphore &);

    void removeThread(class Thread *pThread);

    class SemaphoreEvent : public Event
    {
      public:
        SemaphoreEvent();
        virtual ~SemaphoreEvent();
        virtual size_t serialize(uint8_t *pBuffer);
        static bool unserialize(uint8_t *pBuffer, SemaphoreEvent &event);
        virtual size_t getNumber();
    };

    size_t magic;

    Atomic<ssize_t> m_Counter;
    Spinlock m_BeingModified;
    List<class Thread *> m_Queue;
    bool m_bCanInterrupt;
};

#endif