NAME    [Toc]    [Back]

     pthread_key_create -- thread-specific data key creation

LIBRARY    [Toc]    [Back]

     Reentrant C Library (libc_r, -lc_r)

SYNOPSIS    [Toc]    [Back]

     #include <pthread.h>

     int
     pthread_key_create(pthread_key_t *key, void (*destructor)(void *));

DESCRIPTION    [Toc]    [Back]

     The pthread_key_create() function creates a thread-specific data key visible
 to all threads in the process.  Key values provided by
     pthread_key_create() are opaque objects used to locate thread-specific
     data.  Although the same key value may be used by different threads, the
     values bound to the key by pthread_setspecific() are maintained on a perthread
 basis and persist for the life of the calling thread.

     Upon key creation, the value NULL is associated with the new key in all
     active threads.  Upon thread creation, the value NULL is associated with
     all defined keys in the new thread.

     An optional destructor function may be associated with each key value.
     At thread exit, if a key value has a non-NULL destructor pointer, and the
     thread has a non-NULL value associated with the key, the function pointed
     to is called with the current associated value as its sole argument.  The
     order of destructor calls is unspecified if more than one destructor
     exists for a thread when it exits.

     If, after all the destructors have been called for all non-NULL values
     with associated destructors, there are still some non-NULL values with
     associated destructors, then the process is repeated.  If, after at least
     [PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for outstanding
 non-NULL values, there are still some non-NULL values with associated
 destructors, the implementation stops calling destructors.

RETURN VALUES    [Toc]    [Back]

     If successful, the pthread_key_create() function will store the newly
     created key value at the location specified by key and returns zero.
     Otherwise an error number will be returned to indicate the error.

ERRORS    [Toc]    [Back]

     The pthread_key_create() function will fail if:

     [EAGAIN]		The system lacked the necessary resources to create
			another thread-specific data key, or the systemimposed
 limit on the total number of keys per process
			[PTHREAD_KEYS_MAX] would be exceeded.

     [ENOMEM]		Insufficient memory exists to create the key.

SEE ALSO    [Toc]    [Back]

     pthread_getspecific(3), pthread_key_delete(3), pthread_setspecific(3)

STANDARDS    [Toc]    [Back]

     The pthread_key_create() function conforms to ISO/IEC 9945-1:1996
     (``POSIX.1'').


FreeBSD 5.2.1			 April 4, 1996			 FreeBSD 5.2.1