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1.\" Portions Copyright (c) 2001 Apple Computer, Inc. All Rights Reserved.
2.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
3.\" All rights reserved.
4.\"
5.\" Redistribution and use in source and binary forms, with or without
6.\" modification, are permitted provided that the following conditions
7.\" are met:
8.\" 1. Redistributions of source code must retain the above copyright
9.\" notice, this list of conditions and the following disclaimer.
10.\" 2. Redistributions in binary form must reproduce the above copyright
11.\" notice, this list of conditions and the following disclaimer in the
12.\" documentation and/or other materials provided with the distribution.
13.\" 3. All advertising materials mentioning features or use of this software
14.\" must display the following acknowledgement:
15.\" This product includes software developed by John Birrell.
16.\" 4. Neither the name of the author nor the names of any co-contributors
17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" $FreeBSD: src/share/man/man3/pthread.3,v 1.12.2.4 2001/08/17 13:08:36 ru Exp $
33.\"
34.Dd November 5, 2001
35.Dt PTHREAD 3
36.Os Darwin
37.Sh NAME
38.Nm pthread
39.Nd POSIX thread functions
40.Sh SYNOPSIS
41.Fd #include <pthread.h>
42.Sh DESCRIPTION
43POSIX threads are a set of functions that support applications with
44requirements for multiple flows of control, called
45.Fa threads ,
46within a process.
47Multithreading is used to improve the performance of a
48program.
49.Pp
50The POSIX thread functions are summarized in this section in the following
51groups:
52.Bl -bullet -offset indent
53.It
54Thread Routines
55.It
56Attribute Object Routines
57.It
58Mutex Routines
59.It
60Condition Variable Routines
61.It
62Read/Write Lock Routines
63.It
64Per-Thread Context Routines
65.It
66Cleanup Routines
67.El
68.Sh THREAD ROUTINES
69.Bl -tag -width Er
70.It Xo
71.Ft int
72.Fn pthread_create "pthread_t *thread" "const pthread_attr_t *attr" "void *(*start_routine)(void *)" "void *arg"
73.Xc
74Creates a new thread of execution.
75.It Xo
76.Ft int
77.Fn pthread_detach "pthread_t thread"
78.Xc
79Marks a thread for deletion.
80.It Xo
81.Ft int
82.Fn pthread_equal "pthread_t t1" "pthread_t t2"
83.Xc
84Compares two thread IDs.
85.It Xo
86.Ft void
87.Fn pthread_exit "void *value_ptr"
88.Xc
89Terminates the calling thread.
90.It Xo
91.Ft int
92.Fn pthread_join "pthread_t thread" "void **value_ptr"
93.Xc
94Causes the calling thread to wait for the termination of the specified thread.
95.It Xo
96.Ft int
97.Fn pthread_cancel "pthread_t thread"
98.Xc
99Cancels execution of a thread.
100.It Xo
101.Ft int
102.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)"
103.Xc
104Calls an initialization routine once.
105.It Xo
106.Ft pthread_t
107.Fn pthread_self void
108.Xc
109Returns the thread ID of the calling thread.
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110.It Xo
111.Ft int
112.Fn pthread_atfork "void (*prepare)(void)" "void (*parent)(void)" "void (*child)(void)"
113.Xc
114Registers handlers to be called before and after
115.Fn fork
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116.El
117.Sh ATTRIBUTE OBJECT ROUTINES
118.Bl -tag -width Er
119.It Xo
120.Ft int
121.Fn pthread_attr_destroy "pthread_attr_t *attr"
122.Xc
123Destroy a thread attributes object.
124.It Xo
125.Ft int
126.Fn pthread_attr_getinheritsched "const pthread_attr_t *attr" "int *inheritsched"
127.Xc
128Get the inherit scheduling attribute from a thread attributes object.
129.It Xo
130.Ft int
131.Fn pthread_attr_getschedparam "const pthread_attr_t *attr" "struct sched_param *param"
132.Xc
133Get the scheduling parameter attribute from a thread attributes object.
134.It Xo
135.Ft int
136.Fn pthread_attr_getschedpolicy "const pthread_attr_t *attr" "int *policy"
137.Xc
138Get the scheduling policy attribute from a thread attributes object.
139.It Xo
140.Ft int
141.Fn pthread_attr_getscope "const pthread_attr_t *attr" "int *contentionscope"
142.Xc
143Get the contention scope attribute from a thread attributes object.
144.It Xo
145.Ft int
146.Fn pthread_attr_getstacksize "const pthread_attr_t *attr" "size_t *stacksize"
147.Xc
148Get the stack size attribute from a thread attributes object.
149.It Xo
150.Ft int
151.Fn pthread_attr_getstackaddr "const pthread_attr_t *attr" "void **stackaddr"
152.Xc
153Get the stack address attribute from a thread attributes object.
154.It Xo
155.Ft int
156.Fn pthread_attr_getdetachstate "const pthread_attr_t *attr" "int *detachstate"
157.Xc
158Get the detach state attribute from a thread attributes object.
159.It Xo
160.Ft int
161.Fn pthread_attr_init "pthread_attr_t *attr"
162.Xc
163Initialize a thread attributes object with default values.
164.It Xo
165.Ft int
166.Fn pthread_attr_setinheritsched "pthread_attr_t *attr" "int inheritsched"
167.Xc
168Set the inherit scheduling attribute in a thread attributes object.
169.It Xo
170.Ft int
171.Fn pthread_attr_setschedparam "pthread_attr_t *attr" "const struct sched_param *param"
172.Xc
173Set the scheduling parameter attribute in a thread attributes object.
174.It Xo
175.Ft int
176.Fn pthread_attr_setschedpolicy "pthread_attr_t *attr" "int policy"
177.Xc
178Set the scheduling policy attribute in a thread attributes object.
179.It Xo
180.Ft int
181.Fn pthread_attr_setscope "pthread_attr_t *attr" "int contentionscope"
182.Xc
183Set the contention scope attribute in a thread attributes object.
184.It Xo
185.Ft int
186.Fn pthread_attr_setstacksize "pthread_attr_t *attr" "size_t stacksize"
187.Xc
188Set the stack size attribute in a thread attributes object.
189.It Xo
190.Ft int
191.Fn pthread_attr_setstackaddr "pthread_attr_t *attr" "void *stackaddr"
192.Xc
193Set the stack address attribute in a thread attributes object.
194.It Xo
195.Ft int
196.Fn pthread_attr_setdetachstate "pthread_attr_t *attr" "int detachstate"
197.Xc
198Set the detach state in a thread attributes object.
199.El
200.Sh MUTEX ROUTINES
201.Bl -tag -width Er
202.It Xo
203.Ft int
204.Fn pthread_mutexattr_destroy "pthread_mutexattr_t *attr"
205.Xc
206Destroy a mutex attributes object.
207.It Xo
208.Ft int
209.Fn pthread_mutexattr_init "pthread_mutexattr_t *attr"
210.Xc
211Initialize a mutex attributes object with default values.
212.It Xo
213.Ft int
214.Fn pthread_mutex_destroy "pthread_mutex_t *mutex"
215.Xc
216Destroy a mutex.
217.It Xo
218.Ft int
219.Fn pthread_mutex_init "pthread_mutex_t *mutex" "const pthread_mutexattr_t *attr"
220.Xc
221Initialize a mutex with specified attributes.
222.It Xo
223.Ft int
224.Fn pthread_mutex_lock "pthread_mutex_t *mutex"
225.Xc
226Lock a mutex and block until it becomes available.
227.It Xo
228.Ft int
229.Fn pthread_mutex_trylock "pthread_mutex_t *mutex"
230.Xc
231Try to lock a mutex, but don't block if the mutex is locked by another thread,
232including the current thread.
233.It Xo
234.Ft int
235.Fn pthread_mutex_unlock "pthread_mutex_t *mutex"
236.Xc
237Unlock a mutex.
238.El
239.Sh CONDITION VARIABLE ROUTINES
240.Bl -tag -width Er
241.It Xo
242.Ft int
243.Fn pthread_condattr_init "pthread_condattr_t *attr"
244.Xc
245Initialize a condition variable attributes object with default values.
246.It Xo
247.Ft int
248.Fn pthread_condattr_destroy "pthread_condattr_t *attr"
249.Xc
250Destroy a condition variable attributes object.
251.It Xo
252.Ft int
253.Fn pthread_cond_broadcast "pthread_cond_t *cond"
254.Xc
255Unblock all threads currently blocked on the specified condition variable.
256.It Xo
257.Ft int
258.Fn pthread_cond_destroy "pthread_cond_t *cond"
259.Xc
260Destroy a condition variable.
261.It Xo
262.Ft int
263.Fn pthread_cond_init "pthread_cond_t *cond" "const pthread_condattr_t *attr"
264.Xc
265Initialize a condition variable with specified attributes.
266.It Xo
267.Ft int
268.Fn pthread_cond_signal "pthread_cond_t *cond"
269.Xc
270Unblock at least one of the threads blocked on the specified condition variable.
271.It Xo
272.Ft int
273.Fn pthread_cond_timedwait "pthread_cond_t *cond" "pthread_mutex_t *mutex" "const struct timespec *abstime"
274.Xc
275Wait no longer than the specified time for a condition and lock the specified mutex.
276.It Xo
277.Ft int
278.Fn pthread_cond_wait "pthread_cond_t *" "pthread_mutex_t *mutex"
279.Xc
280Wait for a condition and lock the specified mutex.
281.El
282.Sh READ/WRITE LOCK ROUTINES
283.Bl -tag -width Er
284.It Xo
285.Ft int
286.Fn pthread_rwlock_destroy "pthread_rwlock_t *lock"
287.Xc
288Destroy a read/write lock object.
289.It Xo
290.Ft int
291.Fn pthread_rwlock_init "pthread_rwlock_t *lock" "const pthread_rwlockattr_t *attr"
292.Xc
293Initialize a read/write lock object.
294.It Xo
295.Ft int
296.Fn pthread_rwlock_rdlock "pthread_rwlock_t *lock"
297.Xc
298Lock a read/write lock for reading, blocking until the lock can be
299acquired.
300.It Xo
301.Ft int
302.Fn pthread_rwlock_tryrdlock "pthread_rwlock_t *lock"
303.Xc
304Attempt to lock a read/write lock for reading, without blocking if the
305lock is unavailable.
306.It Xo
307.Ft int
308.Fn pthread_rwlock_trywrlock "pthread_rwlock_t *lock"
309.Xc
310Attempt to lock a read/write lock for writing, without blocking if the
311lock is unavailable.
312.It Xo
313.Ft int
314.Fn pthread_rwlock_unlock "pthread_rwlock_t *lock"
315.Xc
316Unlock a read/write lock.
317.It Xo
318.Ft int
319.Fn pthread_rwlock_wrlock "pthread_rwlock_t *lock"
320.Xc
321Lock a read/write lock for writing, blocking until the lock can be
322acquired.
323.It Xo
324.Ft int
325.Fn pthread_rwlockattr_destroy "pthread_rwlockattr_t *attr"
326.Xc
327Destroy a read/write lock attribute object.
328.It Xo
329.Ft int
330.Fn pthread_rwlockattr_getpshared "const pthread_rwlockattr_t *attr" "int *pshared"
331.Xc
332Retrieve the process shared setting for the read/write lock attribute
333object.
334.It Xo
335.Ft int
336.Fn pthread_rwlockattr_init "pthread_rwlockattr_t *attr"
337.Xc
338Initialize a read/write lock attribute object.
339.It Xo
340.Ft int
341.Fn pthread_rwlockattr_setpshared "pthread_rwlockattr_t *attr" "int pshared"
342.Xc
343Set the process shared setting for the read/write lock attribute object.
344.El
345.Sh PER-THREAD CONTEXT ROUTINES
346.Bl -tag -width Er
347.It Xo
348.Ft int
349.Fn pthread_key_create "pthread_key_t *key" "void (*routine)(void *)"
350.Xc
351Create a thread-specific data key.
352.It Xo
353.Ft int
354.Fn pthread_key_delete "pthread_key_t key"
355.Xc
356Delete a thread-specific data key.
357.It Xo
358.Ft "void *"
359.Fn pthread_getspecific "pthread_key_t key"
360.Xc
361Get the thread-specific value for the specified key.
362.It Xo
363.Ft int
364.Fn pthread_setspecific "pthread_key_t key" "const void *value_ptr"
365.Xc
366Set the thread-specific value for the specified key.
367.El
368.Sh CLEANUP ROUTINES
369.Bl -tag -width Er
370.It Xo
371.Ft void
372.Fn pthread_cleanup_pop "int execute"
373.Xc
374Remove the routine at the top of the calling thread's cancellation cleanup
375stack and optionally invoke it.
376.It Xo
377.Ft void
378.Fn pthread_cleanup_push "void (*routine)(void *)" "void *routine_arg"
379.Xc
380Push the specified cancellation cleanup handler onto the calling thread's
381cancellation stack.
382.El
383.Sh INSTALLATION
384The default system libraries include
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385.Nm pthread
386functions.
387No additional libraries or CFLAGS are necessary to use this API.
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388.Sh SEE ALSO
389.Xr pthread_cleanup_pop 3 ,
390.Xr pthread_cleanup_push 3 ,
391.Xr pthread_cond_broadcast 3 ,
392.Xr pthread_cond_destroy 3 ,
393.Xr pthread_cond_init 3 ,
394.Xr pthread_cond_signal 3 ,
395.Xr pthread_cond_timedwait 3 ,
396.Xr pthread_cond_wait 3 ,
397.Xr pthread_create 3 ,
398.Xr pthread_detach 3 ,
399.Xr pthread_equal 3 ,
400.Xr pthread_exit 3 ,
401.Xr pthread_getspecific 3 ,
402.Xr pthread_join 3 ,
403.Xr pthread_key_delete 3 ,
404.Xr pthread_mutex_destroy 3 ,
405.Xr pthread_mutex_init 3 ,
406.Xr pthread_mutex_lock 3 ,
407.Xr pthread_mutex_trylock 3 ,
408.Xr pthread_mutex_unlock 3 ,
409.Xr pthread_once 3 ,
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410.Xr pthread_rwlock_destroy 3 ,
411.Xr pthread_rwlock_init 3 ,
412.Xr pthread_rwlock_rdlock 3 ,
413.Xr pthread_rwlock_unlock 3 ,
414.Xr pthread_rwlock_wrlock 3 ,
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415.Xr pthread_rwlockattr_destroy 3 ,
416.Xr pthread_rwlockattr_getpshared 3 ,
417.Xr pthread_rwlockattr_init 3 ,
418.Xr pthread_rwlockattr_setpshared 3 ,
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419.Xr pthread_self 3 ,
420.Xr pthread_setspecific 3
421.Sh STANDARDS
422The functions in
423.Fa libc
424with the
425.Fa pthread_
426prefix and not
427.Fa _np
428suffix or
429.Fa pthread_rwlock
430prefix conform to
431.St -p1003.1-96 .
432.Pp
433The functions in libc with the
434.Fa pthread_
435prefix and
436.Fa _np
437suffix are non-portable extensions to POSIX threads.
438.Pp
439The functions in libc with the
440.Fa pthread_rwlock
441prefix are extensions created by The Open Group as part of the
442.St -susv2 .