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ck_swlock(3) FreeBSD Library Functions Manual ck_swlock(3) NAME ck_swlock_init, ck_swlock_write_latch, ck_swlock_write_unlatch, ck_swlock_write_lock, ck_swlock_write_unlock, ck_swlock_write_trylock, ck_swlock_write_downgrade, ck_swlock_locked_writer, ck_swlock_read_lock, ck_swlock_read_trylock, ck_swlock_read_unlock, ck_swlock_locked_reader -- centralized copy-safe write-biased single-writer read-write locks LIBRARY Concurrency Kit (libck, -lck) SYNOPSIS #include <ck_swlock.h> ck_swlock_t lock = CK_SWLOCK_INITIALIZER; void ck_swlock_init(ck_swlock_t *lock); void ck_swlock_write_lock(ck_swlock_t *lock); void ck_swlock_write_unlock(ck_swlock_t *lock); void ck_swlatch_write_latch(ck_swlatch_t *latch); void ck_swlatch_write_unlatch(ck_swlatch_t *latch); bool ck_swlock_write_trylock(ck_swlock_t *lock); bool ck_swlock_write_downgrade(ck_swlock_t *lock); bool ck_swlock_locked_writer(ck_swlock_t *lock); void ck_swlock_read_lock(ck_swlock_t *lock); bool ck_swlock_read_trylock(ck_swlock_t *lock); void ck_swlock_read_unlock(ck_swlock_t *lock); bool ck_swlock_locked_reader(ck_swlock_t *lock); DESCRIPTION This is a centralized write-biased single-writer reader-writer lock. It requires half the space that ck_rwlock does and has a low latency fast path. The lock supports latch and unlatch operations that allow it to be used in a copy-safe manner (reader-bits may be over-written safely). EXAMPLE #include <ck_swlock.h> static ck_swlock_t lock = CK_SWLOCK_INITIALIZER; static void reader(void) { for (;;) { ck_swlock_read_lock(&lock); /* Read-side critical section. */ ck_swlock_read_unlock(&lock); if (ck_swlock_read_trylock(&lock) == true) { /* Read-side critical section. */ ck_swlock_read_unlock(&lock); } } return; } static void writer(void) { ck_swlock_t contrived; for (;;) { ck_swlock_write_lock(&lock); /* Write-side critical section. */ ck_swlock_write_unlock(&lock); if (ck_swlock_write_trylock(&lock) == true) { /* Write-side critical section. */ ck_swlock_write_unlock(&lock); } ck_swlock_write_latch(&lock); /* Write-side critical section. */ /* This is safe to do with-in a latch. */ contrived = lock; lock = contrived; ck_swlock_write_unlatch(&lock); } return; } SEE ALSO ck_brlock(3), ck_elide(3), ck_pflock(3), ck_rwlock(3), ck_tflock(3) Additional information available at http://concurrencykit.org/ April 22, 2014.
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO
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