ck_rwlock man page on DragonFly
[printable version]
ck_rwlock(3) BSD Library Functions Manual ck_rwlock(3)
NAME
ck_rwlock_init, ck_rwlock_write_lock, ck_rwlock_write_unlock,
ck_rwlock_write_trylock, ck_rwlock_write_downgrade,
ck_rwlock_locked_writer, ck_rwlock_read_lock, ck_rwlock_read_trylock,
ck_rwlock_read_unlock, ck_rwlock_locked_reader,
ck_rwlock_recursive_write_lock, ck_rwlock_recursive_write_trylock,
ck_rwlock_recurisve_write_unlock, ck_rwlock_recursive_read_lock,
ck_rwlock_recursive_read_trylock, ck_rwlock_recursive_read_unlock — cen‐
tralized write-biased reader-writer locks
LIBRARY
Concurrency Kit (libck, -lck)
SYNOPSIS
#include <ck_rwlock.h>
ck_rwlock_t lock = CK_RWLOCK_INITIALIZER;
void
ck_rwlock_init(ck_rwlock_t *lock);
void
ck_rwlock_write_lock(ck_rwlock_t *lock);
void
ck_rwlock_write_unlock(ck_rwlock_t *lock);
bool
ck_rwlock_write_trylock(ck_rwlock_t *lock);
bool
ck_rwlock_write_downgrade(ck_rwlock_t *lock);
bool
ck_rwlock_locked_writer(ck_rwlock_t *lock);
void
ck_rwlock_read_lock(ck_rwlock_t *lock);
bool
ck_rwlock_read_trylock(ck_rwlock_t *lock);
void
ck_rwlock_read_unlock(ck_rwlock_t *lock);
bool
ck_rwlock_locked_reader(ck_rwlock_t *lock);
ck_rwlock_recursive_t lock = CK_RWLOCK_RECURSIVE_INITIALIZER;
void
ck_rwlock_recursive_write_lock(ck_rwlock_recursive_t *lock,
unsigned int tid);
bool
ck_rwlock_recursive_write_trylock(ck_rwlock_recursive_t *lock,
unsigned int tid);
void
ck_rwlock_recurisve_write_unlock(ck_rwlock_recursive_t *lock);
void
ck_rwlock_recursive_read_lock(ck_rwlock_recursive_t *lock);
bool
ck_rwlock_recursive_read_trylock(ck_rwlock_recursive_t *lock);
void
ck_rwlock_recursive_read_unlock(ck_rwlock_recursive_t *lock);
DESCRIPTION
This is a centralized write-biased reader-writer lock. It requires very
little space overhead and has a low latency fast path. Write-side recur‐
sion requires usage of ck_rwlock_recursive. Read-side recursion is dis‐
allowed. The ck_rwlock_write_downgrade() function degrades the caller's
write-side acquisition to a read-side acquisition without forfeit of cur‐
rent critical section.
EXAMPLE
#include <ck_rwlock.h>
static ck_rwlock_t lock = CK_RWLOCK_INITIALIZER;
static void
reader(void)
{
for (;;) {
ck_rwlock_read_lock(&lock);
/* Read-side critical section. */
ck_rwlock_read_unlock(&lock);
if (ck_rwlock_read_trylock(&lock) == true) {
/* Read-side critical section. */
ck_rwlock_read_unlock(&lock);
}
}
return;
}
static void
writer(void)
{
for (;;) {
ck_rwlock_write_lock(&lock);
/* Write-side critical section. */
ck_rwlock_write_unlock(&lock);
if (ck_rwlock_write_trylock(&lock, 1) == true) {
/* Write-side critical section. */
ck_rwlock_write_unlock(&lock);
}
}
return;
}
SEE ALSO
ck_brlock(3), ck_elide(3)
Additional information available at http://concurrencykit.org/
July 26, 2013.
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