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NAME
LIBRARYConcurrency Kit (libck, -lck) SYNOPSIS
Arguments of type RWCOHORT must be pointers to structs defined using the CK_RWCOHORT_STRATEGY_PROTOTYPE(3) macro with the same strategy and cohort name as the current call. Arguments of type COHORT must be pointers to structs defined using the CK_COHORT_PROTOTYPE(3) macro. DESCRIPTIONck_rwcohort.h provides an interface for defining reader-writer locks that use cohort locks internally to increase performance on NUMA architectures. See ck_cohort(3) for more information about cohort locks. Before using a reader-writer cohort lock, the user must define a cohort type using either the CK_COHORT_PROTOTYPE(3) or the CK_COHORT_TRYLOCK_PROTOTYPE(3) macros, and define a reader-writer lock type using the CK_RWCOHORT_PROTOTYPE(3) macro. EXAMPLE#include <stdlib.h>
#include <pthread.h>
#include <ck_pr.h>
#include <ck_cohort.h>
#include <ck_rwcohort.h>
#include <ck_spinlock.h>
/* Create cohort methods with signatures that match the required signature */
static void
ck_spinlock_lock_with_context(ck_spinlock_t *lock, void *context)
{
(void)context;
ck_spinlock_lock(lock);
return;
}
static void
ck_spinlock_unlock_with_context(ck_spinlock_t *lock, void *context)
{
(void)context;
ck_spinlock_unlock(lock);
return;
}
static bool
ck_spinlock_locked_with_context(ck_spinlock_t *lock, void *context)
{
(void)context;
return ck_spinlock_locked(lock);
}
/*
* define a cohort type named "test_cohort" that will use
* the above methods for both its global and local locks
*/
CK_COHORT_PROTOTYPE(test_cohort,
ck_spinlock_lock_with_context, ck_spinlock_unlock_with_context, ck_spinlock_locked_with_context,
ck_spinlock_lock_with_context, ck_spinlock_unlock_with_context, ck_spinlock_locked_with_context)
/* define a reader-writer type using the same cohort type */
CK_RWCOHORT_WP_PROTOTYPE(test_cohort)
static ck_spinlock_t global_lock = CK_SPINLOCK_INITIALIZER;
static CK_COHORT_INSTANCE(test_cohort) *cohorts;
static CK_RWCOHORT_WP_INSTANCE(test_cohort) rw_cohort = CK_RWCOHORT_WP_INITIALIZER;
static unsigned int ready;
static void *
function(void *context)
{
CK_COHORT_INSTANCE(test_cohort) *cohort = context;
while (ck_pr_load_uint(&ready) == 0);
while (ck_pr_load_uint(&ready) > 0) {
/*
* acquire the cohort lock before performing critical section.
* note that we pass NULL for both the global and local context
* arguments because neither the lock nor unlock functions
* will use them.
*/
CK_COHORT_LOCK(test_cohort, cohort, NULL, NULL);
/* perform critical section */
/* relinquish cohort lock */
CK_COHORT_UNLOCK(test_cohort, cohort, NULL, NULL);
}
return NULL;
}
int
main(void)
{
unsigned int nthr = 4;
unsigned int n_cohorts = 2;
unsigned int i;
/* allocate 2 cohorts of the defined type */
CK_COHORT_INSTANCE(test_cohort) *cohorts =
calloc(n_cohorts, sizeof(CK_COHORT_INSTANCE(test_cohort)));
/* create local locks to use with each cohort */
ck_spinlock_t *local_locks =
calloc(n_cohorts, sizeof(ck_spinlock_t));
pthread_t *threads =
calloc(nthr, sizeof(pthread_t));
/* initialize each of the cohorts before using them */
for (i = 0 ; i < n_cohorts ; ++i) {
CK_COHORT_INIT(test_cohort, cohorts + i, &global_lock, local_locks + i,
CK_COHORT_DEFAULT_LOCAL_PASS_LIMIT);
}
/* start each thread and assign cohorts equally */
for (i = 0 ; i < nthr ; ++i) {
pthread_create(threads + i, NULL, function, cohorts + (i % n_cohorts));
}
ck_pr_store_uint(&ready, 1);
sleep(10);
ck_pr_store_uint(&ready, 0);
for (i = 0 ; i < nthr ; ++i) {
pthread_join(threads[i], NULL);
}
return 0;
}
SEE ALSOCK_COHORT_PROTOTYPE(3), CK_COHORT_TRYLOCK_PROTOTYPE(3), CK_COHORT_INSTANCE(3), CK_COHORT_INITIALIZER(3), CK_COHORT_INIT(3), CK_COHORT_LOCK(3), CK_COHORT_UNLOCK(3), CK_COHORT_LOCKED(3), CK_COHORT_TRYLOCK(3), Additional information available at http://concurrencykit.org/
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