1.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by John Birrell. 15.\" 4. Neither the name of the author nor the names of any co-contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" $FreeBSD$ 32.\" 33.Dd September 10, 1998 34.Dt PTHREAD 3 35.Os BSD 4 36.Sh NAME 37.Nm pthread 38.Nd POSIX thread functions 39.Sh DESCRIPTION 40POSIX threads are a set of functions that support applications with 41requirements for multiple flows of control, called 42.Fa threads , 43within a process. Multithreading is used to improve the performance of a 44program. 45.Pp 46The POSIX thread functions are summarized in this section in the following 47groups: 48.Bl -bullet -offset indent 49.It 50Thread Routines 51.It 52Attribute Object Routines 53.It 54Mutex Routines 55.It 56Condition Variable Routines 57.It 58Read/Write Lock Routines 59.It 60Per-Thread Context Routines 61.It 62Cleanup Routines 63.El 64.Sh THREAD ROUTINES 65.Bl -tag -width Er 66.It int Fn pthread_create "pthread_t *thread" "const pthread_attr_t *attr" "void *(*start_routine)(void *)" "void *arg" 67Creates a new thread of execution. 68.It int Fn pthread_detach "pthread_t thread" 69Marks a thread for deletion. 70.It int Fn pthread_equal "pthread_t t1" "pthread_t t2" 71Compares two thread IDs. 72.It void Fn pthread_exit "void *value_ptr" 73Terminates the calling thread. 74.It int Fn pthread_join "pthread_t thread" "void **value_ptr" 75Causes the calling thread to wait for the termination of the specified thread. 76.It int Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 77Calls an initialization routine once. 78.It pthread_t Fn pthread_self void 79Returns the thread ID of the calling thread. 80.El 81.Sh ATTRIBUTE OBJECT ROUTINES 82.Bl -tag -width Er 83.It int Fn pthread_attr_destroy "pthread_attr_t *attr" 84Destroy a thread attributes object. 85.It int Fn pthread_attr_getinheritsched "pthread_attr_t *attr" "int *inheritsched" 86Get the inherit scheduling attribute from a thread attributes object. 87.It int Fn pthread_attr_getschedparam "pthread_attr_t *attr" "struct sched_param *param" 88Get the scheduling parameter attribute from a thread attributes object. 89.It int Fn pthread_attr_getschedpolicy "pthread_attr_t *attr" "int *policy" 90Get the scheduling policy attribute from a thread attributes object. 91.It int Fn pthread_attr_getscope "pthread_attr_t *attr" "int *contentionscope" 92Get the contention scope attribute from a thread attributes object. 93.It int Fn pthread_attr_getstacksize "pthread_attr_t *attr" "size_t *stacksize" 94Get the stack size attribute from a thread attributes object. 95.It int Fn pthread_attr_getstackaddr "pthread_attr_t *attr" "void **stackaddr" 96Get the stack address attribute from a thread attributes object. 97.It int Fn pthread_attr_getdetachstate "pthread_attr_t *attr" "int *detachstate" 98Get the detach state attribute from a thread attributes object. 99.It int Fn pthread_attr_init "pthread_attr_t *attr" 100Initialize a thread attributes object with default values. 101.It int Fn pthread_attr_setinheritsched "pthread_attr_t *attr" "int inheritsched" 102Set the inherit scheduling attribute in a thread attributes object. 103.It int Fn pthread_attr_setschedparam "pthread_attr_t *attr" "struct sched_param *param" 104Set the scheduling parameter attribute in a thread attributes object. 105.It int Fn pthread_attr_setschedpolicy "pthread_attr_t *attr" "int policy" 106Set the scheduling policy attribute in a thread attributes object. 107.It int Fn pthread_attr_setscope "pthread_attr_t *attr" "int contentionscope" 108Set the contention scope attribute in a thread attributes object. 109.It int Fn pthread_attr_setstacksize "pthread_attr_t *attr" "size_t stacksize" 110Set the stack size attribute in a thread attributes object. 111.It int Fn pthread_attr_setstackaddr "pthread_attr_t *attr" "void *stackaddr" 112Set the stack address attribute in a thread attributes object. 113.It int Fn pthread_attr_setdetachstate "pthread_attr_t *attr" "int detachstate" 114Set the detach state in a thread attributes object. 115.El 116.Sh MUTEX ROUTINES 117.Bl -tag -width Er 118.It int Fn pthread_mutexattr_destroy "pthread_mutexattr_t *attr" 119Destroy a mutex attributes object. 120.It int Fn pthread_mutexattr_init "pthread_mutexattr_t *attr" 121Initialize a mutex attributes object with default values. 122.It int Fn pthread_mutex_destroy "pthread_mutex_t *mutex" 123Destroy a mutex. 124.It int Fn pthread_mutex_init "pthread_mutex_t *mutex" "const pthread_mutexattr_t *attr" 125Initialize a mutex with specified attributes. 126.It int Fn pthread_mutex_lock "pthread_mutex_t *mutex" 127Lock a mutex and block until it becomes available. 128.It int Fn pthread_mutex_trylock "pthread_mutex_t *mutex" 129Try to lock a mutex, but don't block if the mutex is locked by another thread, 130including the current thread. 131.It int Fn pthread_mutex_unlock "pthread_mutex_t *mutex" 132Unlock a mutex. 133.El 134.Sh CONDITION VARIABLE ROUTINES 135.Bl -tag -width Er 136.It int Fn pthread_condattr_init "pthread_condattr_t *attr" 137Initialize a condition variable attributes object with default values. 138.It int Fn pthread_condattr_destroy "pthread_condattr_t *attr" 139Destroy a condition variable attributes object. 140.It int Fn pthread_cond_broadcast "pthread_cond_t *cond" 141Unblock all threads currently blocked on the specified condition variable. 142.It int Fn pthread_cond_destroy "pthread_cond_t *cond" 143Destroy a condition variable. 144.It int Fn pthread_cond_init "pthread_cond_t *cond" "const pthread_condattr_t *attr" 145Initialize a condition variable with specified attributes. 146.It int Fn pthread_cond_signal "pthread_cond_t *cond" 147Unblock at least one of the threads blocked on the specified condition variable. 148.It int Fn pthread_cond_timedwait "pthread_cond_t *cond" "pthread_mutex_t *mutex" "const struct timespec *abstime" 149Wait no longer than the specified time for a condition and lock the specified mutex. 150.It int Fn pthread_cond_wait "pthread_cond_t *" "pthread_mutex_t *mutex" 151Wait for a condition and lock the specified mutex. 152.El 153.Sh READ/WRITE LOCK ROUTINES 154.Bl -tag -width Er 155.It int Fn pthread_rwlock_destroy "pthread_rwlock_t *lock" 156Destroy a read/write lock object. 157.It int Fn pthread_rwlock_init "pthread_rwlock_t *lock" "const pthread_rwlockattr_t *attr" 158Initialize a read/write lock object. 159.It int Fn pthread_rwlock_rdlock "pthread_rwlock_t *lock" 160Lock a read/write lock for reading, blocking until the lock can be 161acquired. 162.It int Fn pthread_rwlock_tryrdlock "pthread_rwlock_t *lock" 163Attempt to lock a read/write lock for reading, without blocking if the 164lock is unavailable. 165.It int Fn pthread_rwlock_trywrlock "pthread_rwlock_t *lock" 166Attempt to lock a read/write lock for writing, without blocking if the 167lock is unavailable. 168.It int Fn pthread_rwlock_unlock "pthread_rwlock_t *lock" 169Unlock a read/write lock. 170.It int Fn pthread_rwlock_wrlock "pthread_rwlock_t *lock" 171Lock a read/write lock for writing, blocking until the lock can be 172acquired. 173.It int Fn pthread_rwlockattr_destroy "pthread_rwlockattr_t *attr" 174Destroy a read/write lock attribute object. 175.It int Fn pthread_rwlockattr_getpshared "pthread_rwlockattr_t *attr" "int *pshared" 176Retrieve the process shared setting for the read/write lock attribute 177object. 178.It int Fn pthread_rwlockattr_init "pthread_rwlockattr_t *attr" 179Initialize a read/write lock attribute object. 180.It int Fn pthread_rwlockattr_setpshared "pthread_rwlockattr_t *attr" "int *pshared" 181Set the process shared setting for the read/write lock attribute object. 182.El 183.Sh PER-THREAD CONTEXT ROUTINES 184.Bl -tag -width Er 185.It int Fn pthread_key_create "pthread_key_t *key" "void (*routine)(void *)" 186Create a thread-specific data key. 187.It int Fn pthread_key_delete "pthread_key_t key" 188Delete a thread-specific data key. 189.It void * Fn pthread_getspecific "pthread_key_t key" "void **value_ptr" 190Get the thread-specific value for the specified key. 191.It int Fn pthread_setspecific "pthread_key_t key" "const void *value_ptr" 192Set the thread-specific value for the specified key. 193.El 194.Sh CLEANUP ROUTINES 195.Bl -tag -width Er 196.It void Fn pthread_cleanup_pop "int execute" 197Remove the routine at the top of the calling thread's cancellation cleanup 198stack and optionally invoke it. 199.It void Fn pthread_cleanup_push "void (*routine)(void *)" "void *routine_arg" 200Push the specified cancellation cleanup handler onto the calling thread's 201cancellation stack. 202.El 203.Sh INSTALLATION 204The current FreeBSD POSIX thread implementation is built in the library 205.Fa libc_r 206which contains both thread-safe libc functions and the thread functions. 207This library replaces 208.Fa libc 209for threaded applications. 210.Pp 211By default, 212.Fa libc_r 213is built as part of a 'make world'. To disable the build of 214.Fa libc_r 215you must supply the '-DNOLIBC_R' option to 216.Xr make 1 . 217.Pp 218A FreeBSD specific option has been added to gcc to make linking 219threaded processes simple. 220.Fa gcc -pthread 221links a threaded process against 222.Fa libc_r 223instead of 224.Fa libc. 225.Sh STANDARDS 226The functions in 227.Fa libc_r 228with the 229.Fa pthread_ 230prefix and not 231.Fa _np 232suffix or 233.Fa pthread_rwlock 234prefix conform to IEEE 235.Pq Dq Tn POSIX 236Std 1003.1 Second Edition 1996-07-12 237.Pp 238The functions in libc_r with the 239.Fa pthread_ 240prefix and 241.Fa _np 242suffix are non-portable extensions to POSIX threads. 243.Pp 244The functions in libc_r with the 245.Fa pthread_rwlock 246prefix are extensions created by The Open Group as part of the Single 247UNIX Specification, Version 2. 248