/*
 * Copyright 2006, Haiku, Inc. All Rights Reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *              Axel Dörfler, axeld@pinc-software.de
 */
#ifndef LOCK_H
#define LOCK_H


#include <OS.h>


typedef struct lock {
        sem_id  sem;
        int32   count;
} lock;


static inline status_t
init_lock(struct lock *lock, const char *name)
{
        lock->sem = create_sem(0, name);
        lock->count = 0;

        return lock->sem < B_OK ? lock->sem : B_OK;
}


static inline void
uninit_lock(struct lock *lock)
{
        delete_sem(lock->sem);
}


static inline status_t
acquire_lock(struct lock *lock)
{
        if (atomic_add(&lock->count, 1) > 0)
                return acquire_sem(lock->sem);

        return B_OK;
}


static inline status_t
release_lock(struct lock *lock)
{
        if (atomic_add(&lock->count, -1) > 1)
                return release_sem(lock->sem);

        return B_OK;
}


class Autolock {
        public:
                Autolock(struct lock &lock)
                        :
                        fLock(&lock)
                {
                        fStatus = acquire_lock(fLock);
                }

                ~Autolock()
                {
                        if (fStatus == B_OK)
                                release_lock(fLock);
                }

                bool
                IsLocked() const
                {
                        return fStatus == B_OK;
                }

        private:
                status_t        fStatus;
                struct lock     *fLock;
};


#endif  /* LOCK_H */