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.Dd April 4, 1996 32.Dt PTHREAD_KEY_CREATE 3 33.Os 34.Sh NAME 35.Nm pthread_key_create 36.Nd thread-specific data key creation 37.Sh LIBRARY 38.Lb libpthread 39.Sh SYNOPSIS 40.In pthread.h 41.Ft int 42.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)" 43.Sh DESCRIPTION 44The 45.Fn pthread_key_create 46function creates a thread-specific data key visible to all threads in the 47process. 48Key values provided by 49.Fn pthread_key_create 50are opaque objects used to locate thread-specific data. 51Although the same 52key value may be used by different threads, the values bound to the key 53by 54.Fn pthread_setspecific 55are maintained on a per-thread basis and persist for the life of the calling 56thread. 57.Pp 58Upon key creation, the value NULL is associated with the new key in all 59active threads. 60Upon thread creation, the value NULL is associated with all 61defined keys in the new thread. 62.Pp 63An optional destructor function may be associated with each key value. 64At 65thread exit, if a key value has a non-NULL destructor pointer, and the 66thread has a non-NULL value associated with the key, the function pointed 67to is called with the current associated value as its sole argument. 68The 69order of destructor calls is unspecified if more than one destructor exists 70for a thread when it exits. 71.Pp 72If, after all the destructors have been called for all non-NULL values 73with associated destructors, there are still some non-NULL values with 74associated destructors, then the process is repeated. 75If, after at least 76[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for 77outstanding non-NULL values, there are still some non-NULL values with 78associated destructors, the implementation stops calling destructors. 79.Sh RETURN VALUES 80If successful, the 81.Fn pthread_key_create 82function will store the newly created key value at the location specified by 83.Fa key 84and returns zero. 85Otherwise an error number will be returned to indicate 86the error. 87.Sh ERRORS 88The 89.Fn pthread_key_create 90function will fail if: 91.Bl -tag -width Er 92.It Bq Er EAGAIN 93The system lacked the necessary resources to create another thread-specific 94data key, or the system-imposed limit on the total number of keys per process 95[PTHREAD_KEYS_MAX] would be exceeded. 96.It Bq Er ENOMEM 97Insufficient memory exists to create the key. 98.El 99.Sh SEE ALSO 100.Xr pthread_getspecific 3 , 101.Xr pthread_key_delete 3 , 102.Xr pthread_setspecific 3 103.Sh STANDARDS 104The 105.Fn pthread_key_create 106function conforms to 107.St -p1003.1-96 . 108