pthread_key_create(3) [mojave man page]

PTHREAD_KEY_CREATE(3)					   BSD Library Functions Manual 				     PTHREAD_KEY_CREATE(3)

NAME

     pthread_key_create -- thread-specific data key creation

SYNOPSIS

     #include <pthread.h>

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

DESCRIPTION

     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 per-thread 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

     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

     The pthread_key_create() function will fail if:

     [EAGAIN]		The system lacked the necessary resources to create another thread-specific data key, or the system-imposed 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

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

STANDARDS

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

BSD
								   April 4, 1996							       BSD

pthread_key_create(3C)													    pthread_key_create(3C)

NAME

       pthread_key_create - create thread-specific data key

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

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

       This  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 per-thread 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 associ-
       ated 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 that key, the function pointed to is called with the current associated value as its
       sole argument. Destructors can be called in any order.

       If, after all the destructors have been	called for all keys with non-NULL values,  there are still some keys  with  non-NULL  values,  the
       process will be repeated. If, after at least  PTHREAD_DESTRUCTOR_ITERATIONS iterations of destructor calls for outstanding non-NULL values,
       there are still some keys with non-NULL values, the process is continued,   even though this might result in an infinite loop.

       If successful, the pthread_key_create() function stores the newly created key value at *key and returns	0. Otherwise, an error	number	is
       returned to indicate the error.

       The  pthread_key_create() function will fail if:

       EAGAIN	       The  system  lacked  the necessary resources to create another thread-specific data key, or the system-imposed limit on the
		       total number of keys per process PTHREAD_KEYS_MAX has been exceeded.

       ENOMEM	       Insufficient memory exists to create the key.

       The pthread_key_create() function will not return an error code of EINTR.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       pthread_getspecific(3C), pthread_setspecific(3C), pthread_key_delete(3C), attributes(5), standards(5)

								    23 Mar 2005 					    pthread_key_create(3C)