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/*
Copyright (c) 2008-2012 Red Hat, Inc. <http://www.redhat.com>
This file is part of GlusterFS.
This file is licensed to you under your choice of the GNU Lesser
General Public License, version 3 or any later version (LGPLv3 or
later), or the GNU General Public License, version 2 (GPLv2), in all
cases as published by the Free Software Foundation.
*/
#ifndef _LOCKING_H
#define _LOCKING_H
#include <pthread.h>
#if defined(GF_DARWIN_HOST_OS)
#include <libkern/OSAtomic.h>
#define pthread_spinlock_t OSSpinLock
#define pthread_spin_lock(l) OSSpinLockLock(l)
#define pthread_spin_unlock(l) OSSpinLockUnlock(l)
#define pthread_spin_destroy(l) 0
#define pthread_spin_init(l, v) (*l = v)
#endif
#if defined(HAVE_SPINLOCK)
typedef union {
pthread_spinlock_t spinlock;
pthread_mutex_t mutex;
} gf_lock_t;
#if !defined(LOCKING_IMPL)
extern int use_spinlocks;
/*
* Using a dispatch table would be unpleasant because we're dealing with two
* different types. If the dispatch contains direct pointers to pthread_xx
* or mutex_xxx then we have to hope that every possible union alternative
* starts at the same address as the union itself. I'm old enough to remember
* compilers where this was not the case (for alignment reasons) so I'm a bit
* paranoid about that. Also, I don't like casting arguments through "void *"
* which we'd also have to do to avoid type errors. The other alternative would
* be to define actual functions which pick out the right union member, and put
* those in the dispatch tables. Now we have a pointer dereference through the
* dispatch table plus a function call, which is likely to be worse than the
* branching here from the ?: construct. If it were a clear win it might be
* worth the extra complexity, but for now this way seems preferable.
*/
#define LOCK_INIT(x) \
(use_spinlocks ? pthread_spin_init(&((x)->spinlock), 0) \
: pthread_mutex_init(&((x)->mutex), 0))
#define LOCK(x) \
(use_spinlocks ? pthread_spin_lock(&((x)->spinlock)) \
: pthread_mutex_lock(&((x)->mutex)))
#define TRY_LOCK(x) \
(use_spinlocks ? pthread_spin_trylock(&((x)->spinlock)) \
: pthread_mutex_trylock(&((x)->mutex)))
#define UNLOCK(x) \
(use_spinlocks ? pthread_spin_unlock(&((x)->spinlock)) \
: pthread_mutex_unlock(&((x)->mutex)))
#define LOCK_DESTROY(x) \
(use_spinlocks ? pthread_spin_destroy(&((x)->spinlock)) \
: pthread_mutex_destroy(&((x)->mutex)))
#endif
#else
typedef pthread_mutex_t gf_lock_t;
#define LOCK_INIT(x) pthread_mutex_init(x, 0)
#define LOCK(x) pthread_mutex_lock(x)
#define TRY_LOCK(x) pthread_mutex_trylock(x)
#define UNLOCK(x) pthread_mutex_unlock(x)
#define LOCK_DESTROY(x) pthread_mutex_destroy(x)
#endif /* HAVE_SPINLOCK */
#endif /* _LOCKING_H */
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