1 .\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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34 .Dt PTHREAD_KEY_CREATE 3
37 .Nm pthread_key_create
38 .Nd thread-specific data key creation
46 .Fn pthread_key_create "pthread_key_t *key" "void (*destructor)(void *)"
49 .Fn pthread_key_create
50 function creates a thread-specific data key visible to all threads in the
52 Key values provided by
53 .Fn pthread_key_create
54 are opaque objects used to locate thread-specific data.
56 key value may be used by different threads, the values bound to the key
58 .Fn pthread_setspecific
59 are maintained on a per-thread basis and persist for the life of the calling
62 Upon key creation, the value NULL is associated with the new key in all
64 Upon thread creation, the value NULL is associated with all
65 defined keys in the new thread.
67 An optional destructor function may be associated with each key value.
69 thread exit, if a key value has a non-NULL destructor pointer, and the
70 thread has a non-NULL value associated with the key, the function pointed
71 to is called with the current associated value as its sole argument.
73 order of destructor calls is unspecified if more than one destructor exists
74 for a thread when it exits.
76 If, after all the destructors have been called for all non-NULL values
77 with associated destructors, there are still some non-NULL values with
78 associated destructors, then the process is repeated.
80 [PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls for
81 outstanding non-NULL values, there are still some non-NULL values with
82 associated destructors, the implementation stops calling destructors.
85 .Fn pthread_key_create
86 function will store the newly created key value at the location specified by
89 Otherwise an error number will be returned to indicate
93 .Fn pthread_key_create
94 function will fail if:
97 The system lacked the necessary resources to create another thread-specific
98 data key, or the system-imposed limit on the total number of keys per process
99 [PTHREAD_KEYS_MAX] would be exceeded.
101 Insufficient memory exists to create the key.
104 .Xr pthread_getspecific 3 ,
105 .Xr pthread_key_delete 3 ,
106 .Xr pthread_setspecific 3
109 .Fn pthread_key_create