ck_swlock man page

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 ā€” 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/

Referenced By

ck_pflock(3), ck_tflock(3).

April 22, 2014.