OFPlainMutex.h

Go to the documentation of this file.

/*
 * Copyright (c) 2008-2024 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3.0 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * version 3.0 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3.0 along with this program. If not, see
 * <https://www.gnu.org/licenses/>.
 */
 
#include "objfw-defs.h"
 
#include <errno.h>
 
#include "platform.h"
 
#if !defined(OF_HAVE_THREADS) || \
    (!defined(OF_HAVE_PTHREADS) && !defined(OF_WINDOWS) && !defined(OF_AMIGAOS))
# error No mutexes available!
#endif
 
#import "macros.h"
 
#if defined(OF_HAVE_PTHREADS)
# include <pthread.h>
typedef pthread_mutex_t OFPlainMutex;
#elif defined(OF_WINDOWS)
# include <windows.h>
typedef CRITICAL_SECTION OFPlainMutex;
#elif defined(OF_AMIGAOS)
# include <exec/semaphores.h>
typedef struct SignalSemaphore OFPlainMutex;
#endif
 
#if defined(OF_HAVE_ATOMIC_OPS)
# import "OFAtomic.h"
typedef volatile int OFSpinlock;
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
typedef pthread_spinlock_t OFSpinlock;
#else
typedef OFPlainMutex OFSpinlock;
#endif
 
#ifdef OF_HAVE_SCHED_YIELD
# include <sched.h>
#endif
 
#if defined(OF_HAVE_RECURSIVE_PTHREAD_MUTEXES) || defined(OF_WINDOWS) || \
    defined(OF_AMIGAOS)
# define OFPlainRecursiveMutex OFPlainMutex
#else
# import "OFTLSKey.h"
typedef struct {
    OFPlainMutex mutex;
    OFTLSKey count;
} OFPlainRecursiveMutex;
#endif
 
#ifdef __cplusplus
extern "C" {
#endif
extern int OFPlainMutexNew(OFPlainMutex *mutex);
 
extern int OFPlainMutexLock(OFPlainMutex *mutex);
 
extern int OFPlainMutexTryLock(OFPlainMutex *mutex);
 
extern int OFPlainMutexUnlock(OFPlainMutex *mutex);
 
extern int OFPlainMutexFree(OFPlainMutex *mutex);
 
extern int OFPlainRecursiveMutexNew(OFPlainRecursiveMutex *rmutex);
 
extern int OFPlainRecursiveMutexLock(OFPlainRecursiveMutex *rmutex);
 
extern int OFPlainRecursiveMutexTryLock(OFPlainRecursiveMutex *rmutex);
 
extern int OFPlainRecursiveMutexUnlock(OFPlainRecursiveMutex *rmutex);
 
extern int OFPlainRecursiveMutexFree(OFPlainRecursiveMutex *rmutex);
#ifdef __cplusplus
}
#endif
 
/* Spinlocks are inlined for performance. */
 
static OF_INLINE void
OFYieldThread(void)
{
#if defined(OF_HAVE_SCHED_YIELD)
    sched_yield();
#elif defined(OF_WINDOWS)
    Sleep(0);
#endif
}
 
static OF_INLINE int
OFSpinlockNew(OFSpinlock *spinlock)
{
#if defined(OF_HAVE_ATOMIC_OPS)
    *spinlock = 0;
    return 0;
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
    return pthread_spin_init(spinlock, 0);
#else
    return OFPlainMutexNew(spinlock);
#endif
}
 
static OF_INLINE int
OFSpinlockTryLock(OFSpinlock *spinlock)
{
#if defined(OF_HAVE_ATOMIC_OPS)
    if (OFAtomicIntCompareAndSwap(spinlock, 0, 1)) {
        OFAcquireMemoryBarrier();
        return 0;
    }
 
    return EBUSY;
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
    return pthread_spin_trylock(spinlock);
#else
    return OFPlainMutexTryLock(spinlock);
#endif
}
 
static OF_INLINE int
OFSpinlockLock(OFSpinlock *spinlock)
{
#if defined(OF_HAVE_ATOMIC_OPS)
    size_t i;
 
    for (i = 0; i < 10; i++)
        if (OFSpinlockTryLock(spinlock) == 0)
            return 0;
 
    while (OFSpinlockTryLock(spinlock) == EBUSY)
        OFYieldThread();
 
    return 0;
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
    return pthread_spin_lock(spinlock);
#else
    return OFPlainMutexLock(spinlock);
#endif
}
 
static OF_INLINE int
OFSpinlockUnlock(OFSpinlock *spinlock)
{
#if defined(OF_HAVE_ATOMIC_OPS)
    bool ret = OFAtomicIntCompareAndSwap(spinlock, 1, 0);
 
    OFReleaseMemoryBarrier();
 
    return (ret ? 0 : EINVAL);
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
    return pthread_spin_unlock(spinlock);
#else
    return OFPlainMutexUnlock(spinlock);
#endif
}
 
static OF_INLINE int
OFSpinlockFree(OFSpinlock *spinlock)
{
#if defined(OF_HAVE_ATOMIC_OPS)
    return 0;
#elif defined(OF_HAVE_PTHREAD_SPINLOCKS)
    return pthread_spin_destroy(spinlock);
#else
    return OFPlainMutexFree(spinlock);
#endif
}