1.\" $NetBSD: pthread_key_create.3,v 1.2 2003/06/08 06:44:31 thorpej Exp $ 2.\" 3.\" Copyright (c) 2002 The NetBSD Foundation, Inc. 4.\" All rights reserved. 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. Neither the name of The NetBSD Foundation nor the names of its 14.\" contributors may be used to endorse or promote products derived 15.\" from this software without specific prior written permission. 16.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26.\" POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>. 29.\" All rights reserved. 30.\" 31.\" Redistribution and use in source and binary forms, with or without 32.\" modification, are permitted provided that the following conditions 33.\" are met: 34.\" 1. Redistributions of source code must retain the above copyright 35.\" notice, this list of conditions and the following disclaimer. 36.\" 2. Redistributions in binary form must reproduce the above copyright 37.\" notice, this list of conditions and the following disclaimer in the 38.\" documentation and/or other materials provided with the distribution. 39.\" 3. All advertising materials mentioning features or use of this software 40.\" must display the following acknowledgement: 41.\" This product includes software developed by John Birrell. 42.\" 4. Neither the name of the author nor the names of any co-contributors 43.\" may be used to endorse or promote products derived from this software 44.\" without specific prior written permission. 45.\" 46.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 47.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 48.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 49.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 50.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 51.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 52.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 53.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 54.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 55.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 56.\" SUCH DAMAGE. 57.\" 58.\" $FreeBSD: src/lib/libpthread/man/pthread_key_create.3,v 1.12 2002/09/16 19:29:28 mini Exp $ 59.\" 60.Dd January 30, 2003 61.Dt PTHREAD_KEY_CREATE 3 62.Os 63.Sh NAME 64.Nm pthread_key_create 65.Nd thread-specific data key creation 66.Sh LIBRARY 67.Lb libpthread 68.Sh SYNOPSIS 69.In pthread.h 70.Ft int 71.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)" 72.Sh DESCRIPTION 73The 74.Fn pthread_key_create 75function creates a thread-specific data key visible to all threads in the 76process. 77Key values provided by 78.Fn pthread_key_create 79are opaque objects used to locate thread-specific data. 80Although the same 81key value may be used by different threads, the values bound to the key 82by 83.Fn pthread_setspecific 84are maintained on a per-thread basis and persist for the life of the calling 85thread. 86.Pp 87Upon key creation, the value NULL is associated with the new key in all 88active threads. 89Upon thread creation, the value NULL is associated with all 90defined keys in the new thread. 91.Pp 92An optional destructor function may be associated with each key value. 93At 94thread exit, if a key value has a non-NULL destructor pointer, and the 95thread has a non-NULL value associated with the key, the function pointed 96to is called with the current associated value as its sole argument. 97The 98order of destructor calls is unspecified if more than one destructor exists 99for a thread when it exits. 100.Pp 101If, after all the destructors have been called for all non-NULL values 102with associated destructors, there are still some non-NULL values with 103associated destructors, then the process is repeated. 104If, after at least 105[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for 106outstanding non-NULL values, there are still some non-NULL values with 107associated destructors, the implementation stops calling destructors. 108.Sh RETURN VALUES 109If successful, the 110.Fn pthread_key_create 111function will store the newly created key value at the location specified by 112.Fa key 113and returns zero. 114Otherwise an error number will be returned to indicate 115the error. 116.Sh ERRORS 117.Fn pthread_key_create 118shall fail if: 119.Bl -tag -width Er 120.It Bq Er EAGAIN 121The system lacked the necessary resources to create another thread-specific 122data key, or the system-imposed limit on the total number of keys per process 123[PTHREAD_KEYS_MAX] would be exceeded. 124.It Bq Er ENOMEM 125Insufficient memory exists to create the key. 126.El 127.Sh SEE ALSO 128.Xr pthread_getspecific 3 , 129.Xr pthread_key_delete 3 , 130.Xr pthread_setspecific 3 131.Sh STANDARDS 132.Fn pthread_key_create 133conforms to 134.St -p1003.1-96 . 135