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202 lines
6.1 KiB
202 lines
6.1 KiB
.\"
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.\" Copyright 2013 Brendon Scheinman.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\"
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.Dd February 24, 2013.
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.Dt ck_cohort 3
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.Sh NAME
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.Nm ck_cohort
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.Nd generalized interface for lock cohorts
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.Sh LIBRARY
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Concurrency Kit (libck, \-lck)
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.Sh SYNOPSIS
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.In ck_cohort.h
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.Fn CK_COHORT_PROTOTYPE "COHORT_NAME cohort_name" "LOCK_FXN global_lock_method" \
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"LOCK_FXN global_unlock_method" "LOCK_FXN local_lock_method" "LOCK_FXN local_unlock_method"
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.Fn CK_COHORT_TRYLOCK_PROTOTYPE "COHORT_NAME cohort_name" \
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"LOCK_FXN global_lock_method" "LOCK_FXN global_unlock_method" "TRYLOCK_FXN global_trylock_method" \
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"LOCK_FXN local_lock_method" "LOCK_FXN local_unlock_method" "TRYLOCK_FXN local_trylock_method"
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.Fn CK_COHORT_INSTANCE "COHORT_NAME cohort_name"
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.Fn CK_COHORT_INIT "COHORT_NAME cohort_name" "ck_cohort *cohort" \
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"void *global_lock" "void *local_lock" "unsigned int pass_limit"
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.Fn CK_COHORT_LOCK "COHORT_NAME cohort_name" "ck_cohort *cohort" \
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"void *global_context" "void *local_context"
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.Fn CK_COHORT_UNLOCK "COHORT_NAME cohort_name" "ck_cohort *cohort" \
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"void *global_context" "void *local_context"
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.Pp
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Where LOCK_FXN refers to a method with the signature
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.br
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void(void *lock, void *context)
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.br
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and TRYLOCK_FXN refers to a method with the signature
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.br
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bool(void *lock, void *context)
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.Pp
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The
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.Fa context
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argument in each signature is used to pass along any additional information that
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the lock might need for its lock, unlock and trylock methods. The values for this
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argument are provided to each call to
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.Xr CK_COHORT_LOCK 3
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,
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.Xr CK_COHORT_UNLOCK 3
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and
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.Xr CK_COHORT_TRYLOCK 3
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.
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.Sh DESCRIPTION
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ck_cohort.h provides an interface for defining lock cohorts with
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arbitrary lock types. Cohorts are a mechanism for coordinating
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threads on NUMA architectures in order to reduce the frequency
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with which a lock is passed between threads on different clusters.
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.Pp
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Before using a cohort, the user must define a cohort type using
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either the
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.Fn CK_COHORT_PROTOTYPE
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or the
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.Fn CK_COHORT_TRYLOCK_PROTOTYPE
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macros. These macros allow the user to specify the lock methods that
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they would like the cohort to use. See the
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.Xr CK_COHORT_PROTOTYPE 3
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and
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.Xr CK_COHORT_TRYLOCK_PROTOTYPE 3
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man pages for more details.
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.Pp
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.Sh EXAMPLE
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.Bd -literal -offset indent
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#include <stdlib.h>
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#include <pthread.h>
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#include <ck_pr.h>
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#include <ck_cohort.h>
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#include <ck_spinlock.h>
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/*
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* Create lock/unlock methods with signatures that match
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* the required signature
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*/
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static void
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ck_spinlock_lock_with_context(ck_spinlock_t *lock, void *context)
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{
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(void)context;
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ck_spinlock_lock(lock);
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return;
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}
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static void
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ck_spinlock_unlock_with_context(ck_spinlock_t *lock, void *context)
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{
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(void)context;
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ck_spinlock_unlock(lock);
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return;
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}
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/*
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* define a cohort type named "test_cohort" that will use
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* the above methods for both its global and local locks
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*/
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CK_COHORT_PROTOTYPE(test_cohort,
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ck_spinlock_lock_with_context, ck_spinlock_unlock_with_context,
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ck_spinlock_lock_with_context, ck_spinlock_unlock_with_context)
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static ck_spinlock_t global_lock = CK_SPINLOCK_INITIALIZER;
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static unsigned int ready;
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static void *
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function(void *context)
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{
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CK_COHORT_INSTANCE(test_cohort) *cohort = context;
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while (ready == 0);
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while (ready > 0) {
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/*
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* acquire the cohort lock before performing critical section.
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* note that we pass NULL for both the global and local context
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* arguments because neither the lock nor unlock functions
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* will use them.
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*/
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CK_COHORT_LOCK(test_cohort, cohort, NULL, NULL);
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/* perform critical section */
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/* relinquish cohort lock */
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CK_COHORT_UNLOCK(test_cohort, cohort, NULL, NULL);
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}
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return NULL;
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}
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int
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main(void)
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{
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unsigned int nthr = 4;
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unsigned int n_cohorts = 2;
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unsigned int i;
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/* allocate 2 cohorts of the defined type */
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CK_COHORT_INSTANCE(test_cohort) *cohorts =
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calloc(n_cohorts, sizeof(CK_COHORT_INSTANCE(test_cohort)));
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/* create local locks to use with each cohort */
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ck_spinlock_t *local_locks =
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calloc(n_cohorts, sizeof(ck_spinlock_t));
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pthread_t *threads =
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calloc(nthr, sizeof(pthread_t));
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/* initialize each of the cohorts before using them */
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for (i = 0 ; i < n_cohorts ; ++i) {
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CK_COHORT_INIT(test_cohort, cohorts + i, &global_lock, local_locks + i,
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CK_COHORT_DEFAULT_LOCAL_PASS_LIMIT);
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}
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/* start each thread and assign cohorts equally */
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for (i = 0 ; i < nthr ; ++i) {
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pthread_create(threads + i, NULL, function, cohorts + (i % n_cohorts));
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}
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ck_pr_store_uint(&ready, 1);
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sleep(10);
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ck_pr_store_uint(&ready, 0);
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for (i = 0 ; i < nthr ; ++i) {
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pthread_join(threads[i], NULL);
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}
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return 0;
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}
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.Ed
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.Sh SEE ALSO
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.Xr CK_COHORT_PROTOTYPE 3 ,
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.Xr CK_COHORT_TRYLOCK_PROTOTYPE 3 ,
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.Xr CK_COHORT_INSTANCE 3 ,
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.Xr CK_COHORT_INITIALIZER 3 ,
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.Xr CK_COHORT_INIT 3 ,
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.Xr CK_COHORT_LOCK 3 ,
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.Xr CK_COHORT_UNLOCK 3 ,
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.Xr CK_COHORT_TRYLOCK 3 ,
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.Pp
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Additional information available at http://concurrencykit.org/
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