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: src/share/man/man3/pthread_key_create.3,v 1.16 2007/10/22 10:08:00 ru Exp $ 32.\" 33.Dd July 10, 2009 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 libpthread 41.Sh SYNOPSIS 42.In pthread.h 43.Ft int 44.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)" 45.Sh DESCRIPTION 46The 47.Fn pthread_key_create 48function creates a thread-specific data key visible to all threads in the 49process. 50Key values provided by 51.Fn pthread_key_create 52are opaque objects used to locate thread-specific data. 53Although the same 54key value may be used by different threads, the values bound to the key 55by 56.Fn pthread_setspecific 57are maintained on a per-thread basis and persist for the life of the calling 58thread. 59.Pp 60Upon key creation, the value NULL is associated with the new key in all 61active threads. 62Upon thread creation, the value NULL is associated with all 63defined keys in the new thread. 64.Pp 65An optional destructor function may be associated with each key value. 66At 67thread exit, if a key value has a non-NULL destructor pointer, and the 68thread has a non-NULL value associated with the key, the function pointed 69to is called with the current associated value as its sole argument. 70The 71order of destructor calls is unspecified if more than one destructor exists 72for a thread when it exits. 73.Pp 74If, after all the destructors have been called for all non-NULL values 75with associated destructors, there are still some non-NULL values with 76associated destructors, then the process is repeated. 77If, after at least 78[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for 79outstanding non-NULL values, there are still some non-NULL values with 80associated destructors, the implementation stops calling destructors. 81.Sh RETURN VALUES 82If successful, the 83.Fn pthread_key_create 84function will store the newly created key value at the location specified by 85.Fa key 86and returns zero. 87Otherwise an error number will be returned to indicate 88the error. 89.Sh ERRORS 90The 91.Fn pthread_key_create 92function will fail if: 93.Bl -tag -width Er 94.It Bq Er EAGAIN 95The system lacked the necessary resources to create another thread-specific 96data key, or the system-imposed limit on the total number of keys per process 97[PTHREAD_KEYS_MAX] would be exceeded. 98.It Bq Er ENOMEM 99Insufficient memory exists to create the key. 100.El 101.Sh SEE ALSO 102.Xr pthread_getspecific 3 , 103.Xr pthread_key_delete 3 , 104.Xr pthread_setspecific 3 105.Sh STANDARDS 106The 107.Fn pthread_key_create 108function conforms to 109.St -p1003.1-96 . 110