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ck_brlock(3) Library Functions Manual ck_brlock(3)

NAME

ck_brlock_init, ck_brlock_write_lock, ck_brlock_write_unlock, ck_brlock_write_trylock, ck_brlock_read_register, ck_brlock_read_unregister, ck_brlock_read_lock, ck_brlock_read_trylock, ck_brlock_read_unlock —
big-reader locks

LIBRARY

Concurrency Kit (libck, -lck)

SYNOPSIS

#include <ck_brlock.h>
ck_brlock_t brlock = CK_BRLOCK_INITIALIZER;
ck_brlock_reader_t reader = CK_BRLOCK_READER_INITIALIZER;

void
ck_brlock_init(ck_brlock_t *br);
void
ck_brlock_write_lock(ck_brlock_t *br);
void
ck_brlock_write_unlock(ck_brlock_t *br);
bool
ck_brlock_write_trylock(ck_brlock_t *br, unsigned int factor);
void
ck_brlock_read_register(ck_brlock_t *br, ck_brlock_reader_t *reader);
void
ck_brlock_read_unregister(ck_brlock_t *br, ck_brlock_reader_t *reader);
void
ck_brlock_read_lock(ck_brlock_t *br, ck_brlock_reader_t *reader);
bool
ck_brlock_read_trylock(ck_brlock_t *br, ck_brlock_reader_t *reader, unsigned int factor);
void
ck_brlock_read_unlock(ck_brlock_reader_t *reader);

DESCRIPTION

Big reader locks are distributed reader-writer locks with low latency constant time reader acquisition (with respect to number of concurrent readers). On the other hand, writer acquisitions are a relatively expensive O(n) operation. This is a write-biased lock.

EXAMPLE

static ck_brlock_t lock = CK_BRLOCK_INITIALIZER; 
static __thread ck_brlock_reader_t reader; 
 
static void 
reader(void) 
{ 
 
	/* Add our thread as a lock participant. */ 
	ck_brlock_read_register(&lock, &reader); 
 
	for (;;) { 
		ck_brlock_read_lock(&lock, &reader); 
		/* Read-side critical section. */ 
		ck_brlock_read_unlock(&reader); 
 
		if (ck_brlock_read_trylock(&lock, &reader, 1) == true) { 
			/* Read-side critical section. */ 
			ck_brlock_read_unlock(&reader); 
		} 
	} 
 
	return; 
} 
 
static void 
writer(void) 
{ 
 
	for (;;) { 
		ck_brlock_write_lock(&lock); 
		/* Write-side critical section. */ 
		ck_brlock_write_unlock(&lock); 
 
		if (ck_brlock_write_trylock(&lock, 1) == true) { 
			/* Write-side critical section. */ 
			ck_brlock_write_unlock(&lock); 
		} 
	} 
 
	return; 
}

SEE ALSO

ck_bytelock(3), ck_rwlock(3)
Additional information available at http://concurrencykit.org/
July 26, 2013.