111 lines
4.2 KiB
Groff
111 lines
4.2 KiB
Groff
.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by John Birrell.
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.\" 4. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 4, 1996
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.Dt PTHREAD_KEY_CREATE 3
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.Os
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.Sh NAME
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.Nm pthread_key_create
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.Nd thread-specific data key creation
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.Sh LIBRARY
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.Lb libpthread
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.Lb libthr
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.Sh SYNOPSIS
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.In pthread.h
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.Ft int
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.Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)"
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.Sh DESCRIPTION
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The
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.Fn pthread_key_create
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function creates a thread-specific data key visible to all threads in the
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process.
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Key values provided by
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.Fn pthread_key_create
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are opaque objects used to locate thread-specific data.
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Although the same
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key value may be used by different threads, the values bound to the key
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by
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.Fn pthread_setspecific
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are maintained on a per-thread basis and persist for the life of the calling
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thread.
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.Pp
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Upon key creation, the value NULL is associated with the new key in all
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active threads.
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Upon thread creation, the value NULL is associated with all
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defined keys in the new thread.
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.Pp
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An optional destructor function may be associated with each key value.
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At
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thread exit, if a key value has a non-NULL destructor pointer, and the
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thread has a non-NULL value associated with the key, the function pointed
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to is called with the current associated value as its sole argument.
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The
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order of destructor calls is unspecified if more than one destructor exists
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for a thread when it exits.
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.Pp
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If, after all the destructors have been called for all non-NULL values
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with associated destructors, there are still some non-NULL values with
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associated destructors, then the process is repeated.
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If, after at least
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[PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for
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outstanding non-NULL values, there are still some non-NULL values with
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associated destructors, the implementation stops calling destructors.
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.Sh RETURN VALUES
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If successful, the
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.Fn pthread_key_create
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function will store the newly created key value at the location specified by
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.Fa key
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and returns zero.
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Otherwise an error number will be returned to indicate
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the error.
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.Sh ERRORS
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The
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.Fn pthread_key_create
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The system lacked the necessary resources to create another thread-specific
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data key, or the system-imposed limit on the total number of keys per process
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[PTHREAD_KEYS_MAX] would be exceeded.
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.It Bq Er ENOMEM
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Insufficient memory exists to create the key.
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.El
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.Sh SEE ALSO
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.Xr pthread_getspecific 3 ,
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.Xr pthread_key_delete 3 ,
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.Xr pthread_setspecific 3
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.Sh STANDARDS
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The
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.Fn pthread_key_create
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function conforms to
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.St -p1003.1-96 .
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