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diff --git a/doc/ck_rwcohort b/doc/ck_rwcohort new file mode 100644 index 0000000..ba2b5f9 --- /dev/null +++ b/doc/ck_rwcohort @@ -0,0 +1,203 @@ +.\" +.\" Copyright 2013 Brendon Scheinman. +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" +.Dd April 23, 2013. +.Dt ck_rwcohort 3 +.Sh NAME +.Nm ck_rwcohort +.Nd generalized interface for reader-writer locks using cohort locks +.Sh LIBRARY +Concurrency Kit (libck, \-lck) +.Sh SYNOPSIS +.In ck_rwcohort.h +In each of the following macros, "STRATEGY" should be replaced with either "NEUTRAL", "RP", or "WP" +depending on which locking strategy the user prefers. RP and WP represent reader preference and +writer preference, respectively, while NEUTRAL represents a strategy neutral to reads vs. writes. +.Fn CK_RWCOHORT_STRATEGY_PROTOTYPE "COHORT_NAME cohort_name" +.Fn CK_RWCOHORT_STRATEGY_NAME "COHORT_NAME cohort_name" +.Fn CK_RWCOHORT_STRATEGY_INSTANCE "COHORT_NAME cohort_name" +.Fn 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 +.Fn CK_RWCOHORT_STRATEGY_READ_LOCK "COHORT_NAME cohort_name" "RWCOHORT lock" "COHORT cohort" \ +"void *global_context" "void *local_context" +.Fn CK_RWCOHORT_STRATEGY_READ_UNLOCK "COHORT_NAME cohort_name" "RWCOHORT lock" "COHORT cohort" \ +"void *global_context" "void *local_context" +.Fn CK_RWCOHORT_STRATEGY_WRITE_LOCK "COHORT_NAME cohort_name" "RWCOHORT lock" "COHORT cohort" \ +"void *global_context" "void *local_context" +.Fn CK_RWCOHORT_STRATEGY_WRITE_UNLOCK "COHORT_NAME cohort_name" "RWCOHORT lock" "COHORT cohort" \ +"void *global_context" "void *local_context" +.Pp +Arguments of type RWCOHORT must be pointers to structs defined using the +.Xr CK_RWCOHORT_STRATEGY_PROTOTYPE 3 +macro with the same strategy and cohort name as the current call. +.Pp +Arguments of type COHORT must be pointers to structs defined using the +.Xr CK_COHORT_PROTOTYPE 3 +macro. +.Sh DESCRIPTION +ck_rwcohort.h provides an interface for defining reader-writer locks +that use cohort locks internally to increase performance on NUMA +architectures. See +.Xr ck_cohort 3 +for more information about cohort locks. +.Pp +Before using a reader-writer cohort lock, the user must define a cohort type using +either the +.Xr CK_COHORT_PROTOTYPE 3 +or the +.Xr CK_COHORT_TRYLOCK_PROTOTYPE 3 +macros, and define a reader-writer lock type using the +.Xr CK_RWCOHORT_PROTOTYPE 3 +macro. +.Pp +.Sh EXAMPLE +.Bd -literal -offset indent +#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; +} +.Ed +.Sh SEE ALSO +.Xr CK_COHORT_PROTOTYPE 3 , +.Xr CK_COHORT_TRYLOCK_PROTOTYPE 3 , +.Xr CK_COHORT_INSTANCE 3 , +.Xr CK_COHORT_INITIALIZER 3 , +.Xr CK_COHORT_INIT 3 , +.Xr CK_COHORT_LOCK 3 , +.Xr CK_COHORT_UNLOCK 3 , +.Xr CK_COHORT_LOCKED 3 , +.Xr CK_COHORT_TRYLOCK 3 , +.Pp +Additional information available at http://concurrencykit.org/ |