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NAME ck_rwcohort -- generalized interface for reader-writer locks using co- hort locks LIBRARY Concurrency Kit (libck, -lck) SYNOPSIS #include <ck_rwcohort.h> In each of the following macros, "STRATEGY" should be replaced with ei- ther "NEUTRAL", "RP", or "WP" depending on which locking strategy the user prefers. RP and WP represent reader preference and writer prefer- ence, respectively, while NEUTRAL represents a strategy neutral to reads vs. writes. CK_RWCOHORT_STRATEGY_PROTOTYPE(COHORT_NAME cohort_name); CK_RWCOHORT_STRATEGY_NAME(COHORT_NAME cohort_name); CK_RWCOHORT_STRATEGY_INSTANCE(COHORT_NAME cohort_name); CK_RWCOHORT_STRATEGY_INIT(COHORT_NAME cohort_name, RWCOHORT lock, unsigned int wait_limit); Note: the wait_limit argument should be omitted for locks using the neutral strategy CK_RWCOHORT_STRATEGY_READ_LOCK(COHORT_NAME cohort_name, RWCOHORT lock, COHORT cohort, void *global_context, void *local_context); CK_RWCOHORT_STRATEGY_READ_UNLOCK(COHORT_NAME cohort_name, RWCOHORT lock, COHORT cohort, void *global_context, void *local_context); CK_RWCOHORT_STRATEGY_WRITE_LOCK(COHORT_NAME cohort_name, RWCOHORT lock, COHORT cohort, void *global_context, void *local_context); CK_RWCOHORT_STRATEGY_WRITE_UNLOCK(COHORT_NAME cohort_name, RWCOHORT lock, COHORT cohort, void *global_context, void *local_context); 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. DESCRIPTION ck_rwcohort.h provides an interface for defining reader-writer locks that use cohort locks internally to increase performance on NUMA archi- tectures. 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 ALSO CK_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/ April 23, 2013. ck_rwcohort(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO
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