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b497e90179
The spinlock is small (atomic_uint_fast32_t at most), lightweight synchronization primitive and should only be used for short-lived and most of the time a isc_mutex should be used. Add a isc_spinlock unit which is either (most of the time) a think wrapper around pthread_spin API or an efficient shim implementation of the simple spinlock.
125 lines
3.8 KiB
C
125 lines
3.8 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#pragma once
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/*! \file */
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#include <pthread.h>
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#include <stdlib.h>
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#include <isc/atomic.h>
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#include <isc/lang.h>
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#include <isc/util.h>
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ISC_LANG_BEGINDECLS
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/*
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* We use macros instead of static inline functions so that the exact code
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* location can be reported when PTHREADS_RUNTIME_CHECK() fails or when mutrace
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* reports lock contention.
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*/
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#ifdef ISC_TRACK_PTHREADS_OBJECTS
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#define isc_spinlock_init(sp) \
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{ \
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*sp = malloc(sizeof(**sp)); \
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isc__spinlock_init(*sp); \
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}
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#define isc_spinlock_lock(sp) isc__spinlock_lock(*sp)
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#define isc_spinlock_unlock(sp) isc__spinlock_unlock(*sp)
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#define isc_spinlock_destroy(sp) \
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{ \
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isc__spinlock_destroy(*sp); \
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free((void *)*sp); \
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}
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#else /* ISC_TRACK_PTHREADS_OBJECTS */
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#define isc_spinlock_init(sp) isc__spinlock_init(sp)
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#define isc_spinlock_lock(sp) isc__spinlock_lock(sp)
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#define isc_spinlock_unlock(sp) isc__spinlock_unlock(sp)
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#define isc_spinlock_destroy(sp) isc__spinlock_destroy(sp)
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#endif /* ISC_TRACK_PTHREADS_OBJECTS */
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#if HAVE_PTHREAD_SPIN_INIT
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#if ISC_TRACK_PTHREADS_OBJECTS
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typedef pthread_spinlock_t *isc_spinlock_t;
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#else /* ISC_TRACK_PTHREADS_OBJECTS */
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typedef pthread_spinlock_t isc_spinlock_t;
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#endif /* ISC_TRACK_PTHREADS_OBJECTS */
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#define isc__spinlock_init(sp) \
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{ \
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int _ret = pthread_spin_init(sp, PTHREAD_PROCESS_PRIVATE); \
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PTHREADS_RUNTIME_CHECK(pthread_spin_init, _ret); \
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}
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#define isc__spinlock_lock(sp) \
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{ \
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int _ret = pthread_spin_lock(sp); \
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PTHREADS_RUNTIME_CHECK(pthread_spin_lock, _ret); \
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}
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#define isc__spinlock_unlock(sp) \
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{ \
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int _ret = pthread_spin_unlock(sp); \
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PTHREADS_RUNTIME_CHECK(pthread_spin_unlock, _ret); \
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}
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#define isc__spinlock_destroy(sp) \
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{ \
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int _ret = pthread_spin_destroy(sp); \
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PTHREADS_RUNTIME_CHECK(pthread_spin_destroy, _ret); \
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}
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#else /* HAVE_PTHREAD_SPIN_INIT */
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#if ISC_TRACK_PTHREADS_OBJECTS
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typedef atomic_uint_fast32_t *isc_spinlock_t;
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#else /* ISC_TRACK_PTHREADS_OBJECTS */
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typedef atomic_uint_fast32_t isc_spinlock_t;
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#endif /* ISC_TRACK_PTHREADS_OBJECTS */
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#define isc__spinlock_init(sp) \
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{ \
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atomic_init(sp, 0); \
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}
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#define isc__spinlock_lock(sp) \
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{ \
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while (!atomic_compare_exchange_weak_acq_rel( \
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sp, &(uint_fast32_t){ 0 }, 1)) \
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{ \
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do { \
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isc_pause(); \
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} while (atomic_load_relaxed(sp) != 0); \
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} \
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}
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#define isc__spinlock_unlock(sp) \
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{ \
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atomic_store_release(sp, 0); \
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}
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#define isc__spinlock_destroy(sp) \
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{ \
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INSIST(atomic_load(sp) == 0); \
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}
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#endif
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ISC_LANG_ENDDECLS
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