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 April 4, 1996 34.Dt PTHREAD_KEY_CREATE 3 35.Os 36.Sh NAME 37.Nm pthread_key_create 38.Nd thread-specific data key creation 39.Sh LIBRARY 40.Lb libc_r 41.Lb libpthread 42.Lb libthr 43.Sh SYNOPSIS 44.In pthread.h 45.Ft int 46.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)" 47.Sh DESCRIPTION 48The 49.Fn pthread_key_create 50function creates a thread-specific data key visible to all threads in the 51process. 52Key values provided by 53.Fn pthread_key_create 54are opaque objects used to locate thread-specific data. 55Although the same 56key value may be used by different threads, the values bound to the key 57by 58.Fn pthread_setspecific 59are maintained on a per-thread basis and persist for the life of the calling 60thread. 61.Pp 62Upon key creation, the value NULL is associated with the new key in all 63active threads. 64Upon thread creation, the value NULL is associated with all 65defined keys in the new thread. 66.Pp 67An optional destructor function may be associated with each key value. 68At 69thread exit, if a key value has a non-NULL destructor pointer, and the 70thread has a non-NULL value associated with the key, the function pointed 71to is called with the current associated value as its sole argument. 72The 73order of destructor calls is unspecified if more than one destructor exists 74for a thread when it exits. 75.Pp 76If, after all the destructors have been called for all non-NULL values 77with associated destructors, there are still some non-NULL values with 78associated destructors, then the process is repeated. 79If, after at least 80[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for 81outstanding non-NULL values, there are still some non-NULL values with 82associated destructors, the implementation stops calling destructors. 83.Sh RETURN VALUES 84If successful, the 85.Fn pthread_key_create 86function will store the newly created key value at the location specified by 87.Fa key 88and returns zero. 89Otherwise an error number will be returned to indicate 90the error. 91.Sh ERRORS 92The 93.Fn pthread_key_create 94function will fail if: 95.Bl -tag -width Er 96.It Bq Er EAGAIN 97The system lacked the necessary resources to create another thread-specific 98data key, or the system-imposed limit on the total number of keys per process 99[PTHREAD_KEYS_MAX] would be exceeded. 100.It Bq Er ENOMEM 101Insufficient memory exists to create the key. 102.El 103.Sh SEE ALSO 104.Xr pthread_getspecific 3 , 105.Xr pthread_key_delete 3 , 106.Xr pthread_setspecific 3 107.Sh STANDARDS 108The 109.Fn pthread_key_create 110function conforms to 111.St -p1003.1-96 . 112