1 .\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
2 .\" All rights reserved.
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32 .Dt PTHREAD_KEY_CREATE 3
35 .Nm pthread_key_create
36 .Nd thread-specific data key creation
38 .Fd #include <pthread.h>
40 .Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)"
43 .Fn pthread_key_create
44 function creates a thread-specific data key visible to all threads in the
45 process. Key values provided by
46 .Fn pthread_key_create
47 are opaque objects used to locate thread-specific data. Although the same
48 key value may be used by different threads, the values bound to the key
50 .Fn pthread_setspecific
51 are maintained on a per-thread basis and persist for the life of the calling
54 Upon key creation, the value NULL is associated with the new key in all
55 active threads. Upon thread creation, the value NULL is associated with all
56 defined keys in the new thread.
58 An optional destructor function may be associated with each key value. At
59 thread exit, if a key value has a non-NULL destructor pointer, and the
60 thread has a non-NULL value associated with the key, the function pointed
61 to is called with the current associated value as its sole argument. The
62 order of destructor calls is unspecified if more than one destructor exists
63 for a thread when it exits.
65 If, after all the destructors have been called for all non-NULL values
66 with associated destructors, there are still some non-NULL values with
67 associated destructors, then the process is repeated. If, after at least
68 [PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for
69 outstanding non-NULL values, there are still some non-NULL values with
70 associated destructors, the implementation stops calling destructors.
73 .Fn pthread_key_create
74 function will store the newly created key value at the location specified by
76 and returns zero. Otherwise an error number will be returned to indicate
79 .Fn pthread_key_create
83 The system lacked the necessary resources to create another thread-specific
84 data key, or the system-imposed limit on the total number of keys per process
85 [PTHREAD_KEYS_MAX] would be exceeded.
87 Insufficient memory exists to create the key.
91 .Xr pthread_getspecific 3 ,
92 .Xr pthread_key_delete 3 ,
93 .Xr pthread_setspecific 3
95 .Fn pthread_key_create
96 conforms to ISO/IEC 9945-1 ANSI/IEEE
98 Std 1003.1 Second Edition 1996-07-12.