LIBRARY

Concurrency Kit (libck, -lck)

SYNOPSIS

In ck_brlock.h

ck_brlock_t brlock = CK_BRLOCK_INITIALIZER;

ck_brlock_reader_t reader = CK_BRLOCK_READER_INITIALIZER;

Ft void Fn ck_brlock_init ck_brlock_t *br Ft void Fn ck_brlock_write_lock ck_brlock_t *br Ft void Fn ck_brlock_write_unlock ck_brlock_t *br Ft bool Fn ck_brlock_write_trylock ck_brlock_t *br unsigned int factor Ft void Fn ck_brlock_read_register ck_brlock_t *br ck_brlock_reader_t *reader Ft void Fn ck_brlock_read_unregister ck_brlock_t *br ck_brlock_reader_t *reader Ft void Fn ck_brlock_read_lock ck_brlock_t *br ck_brlock_reader_t *reader Ft bool Fn ck_brlock_read_trylock ck_brlock_t *br ck_brlock_reader_t *reader unsigned int factor Ft void Fn 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;
}