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/