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.\" $DragonFly: src/lib/libc_r/man/pthread_key_create.3,v 1.2 2003/06/17 04:26:48 dillon Exp $ 33.\" 34.Dd July 10, 2009 35.Dt PTHREAD_KEY_CREATE 3 36.Os 37.Sh NAME 38.Nm pthread_key_create 39.Nd thread-specific data key creation 40.Sh LIBRARY 41.Lb libpthread 42.Sh SYNOPSIS 43.In pthread.h 44.Ft int 45.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)" 46.Sh DESCRIPTION 47The 48.Fn pthread_key_create 49function creates a thread-specific data key visible to all threads in the 50process. 51Key values provided by 52.Fn pthread_key_create 53are opaque objects used to locate thread-specific data. 54Although the same 55key value may be used by different threads, the values bound to the key 56by 57.Fn pthread_setspecific 58are maintained on a per-thread basis and persist for the life of the calling 59thread. 60.Pp 61Upon key creation, the value NULL is associated with the new key in all 62active threads. 63Upon thread creation, the value NULL is associated with all 64defined keys in the new thread. 65.Pp 66An optional destructor function may be associated with each key value. 67At 68thread exit, if a key value has a non-NULL destructor pointer, and the 69thread has a non-NULL value associated with the key, the function pointed 70to is called with the current associated value as its sole argument. 71The 72order of destructor calls is unspecified if more than one destructor exists 73for a thread when it exits. 74.Pp 75If, after all the destructors have been called for all non-NULL values 76with associated destructors, there are still some non-NULL values with 77associated destructors, then the process is repeated. 78If, after at least 79[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for 80outstanding non-NULL values, there are still some non-NULL values with 81associated destructors, the implementation stops calling destructors. 82.Sh RETURN VALUES 83If successful, the 84.Fn pthread_key_create 85function will store the newly created key value at the location specified by 86.Fa key 87and returns zero. 88Otherwise an error number will be returned to indicate 89the error. 90.Sh ERRORS 91The 92.Fn pthread_key_create 93function will fail if: 94.Bl -tag -width Er 95.It Bq Er EAGAIN 96The system lacked the necessary resources to create another thread-specific 97data key, or the system-imposed limit on the total number of keys per process 98[PTHREAD_KEYS_MAX] would be exceeded. 99.It Bq Er ENOMEM 100Insufficient memory exists to create the key. 101.El 102.Sh SEE ALSO 103.Xr pthread_getspecific 3 , 104.Xr pthread_key_delete 3 , 105.Xr pthread_setspecific 3 106.Sh STANDARDS 107The 108.Fn pthread_key_create 109function conforms to 110.St -p1003.1-96 . 111