30 lines
922 B
C
30 lines
922 B
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef PERF_SHARDED_MUTEX_H
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#define PERF_SHARDED_MUTEX_H
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#include "mutex.h"
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#include "hashmap.h"
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/*
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* In a situation where a lock is needed per object, having a mutex can be
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* relatively memory expensive (40 bytes on x86-64). If the object can be
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* constantly hashed, a sharded mutex is an alternative global pool of mutexes
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* where the mutex is looked up from a hash value. This can lead to collisions
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* if the number of shards isn't large enough.
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*/
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struct sharded_mutex {
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/* mutexes array is 1<<cap_bits in size. */
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unsigned int cap_bits;
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struct mutex mutexes[];
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};
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struct sharded_mutex *sharded_mutex__new(size_t num_shards);
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void sharded_mutex__delete(struct sharded_mutex *sm);
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static inline struct mutex *sharded_mutex__get_mutex(struct sharded_mutex *sm, size_t hash)
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{
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return &sm->mutexes[hash_bits(hash, sm->cap_bits)];
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}
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#endif /* PERF_SHARDED_MUTEX_H */
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