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/*
* Copyright (c) 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FAT_RWLOCK_H
#define FAT_RWLOCK_H 1
#include "compiler.h"
#include "list.h"
#include "ovs-thread.h"
/* "Fat rwlock".
*
* This implements a reader-writer lock that uses a lot of memory (128 to 192
* bytes per thread that takes the lock) but avoids cache line bouncing when
* taking the read side. Thus, a fat_rwlock is a good choice for rwlocks taken
* frequently by readers.
*/
struct OVS_LOCKABLE fat_rwlock {
ovsthread_key_t key;
/* Contains "struct fat_rwlock_slot"s, one for each thread that has taken
* this lock. Guarded by 'mutex'. */
struct ovs_list threads OVS_GUARDED;
struct ovs_mutex mutex;
};
void fat_rwlock_init(struct fat_rwlock *);
void fat_rwlock_destroy(struct fat_rwlock *);
void fat_rwlock_rdlock(const struct fat_rwlock *rwlock) OVS_ACQ_RDLOCK(rwlock);
int fat_rwlock_tryrdlock(const struct fat_rwlock *rwlock)
OVS_TRY_RDLOCK(0, rwlock);
void fat_rwlock_wrlock(const struct fat_rwlock *rwlock) OVS_ACQ_WRLOCK(rwlock);
void fat_rwlock_unlock(const struct fat_rwlock *rwlock) OVS_RELEASES(rwlock);
#endif /* fat-rwlock.h */
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