xref: /freebsd/share/man/man3/pthread_setspecific.3 (revision cd0d51baaa4509a1db83251a601d34404d20c990)
1.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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31.\" $FreeBSD$
32.\"
33.Dd April 4, 1996
34.Dt PTHREAD_SETSPECIFIC 3
35.Os
36.Sh NAME
37.Nm pthread_setspecific
38.Nd set a thread-specific data value
39.Sh LIBRARY
40.Lb libpthread
41.Sh SYNOPSIS
42.In pthread.h
43.Ft int
44.Fn pthread_setspecific "pthread_key_t key" "const void *value"
45.Sh DESCRIPTION
46The
47.Fn pthread_setspecific
48function associates a thread-specific value with a
49.Fa key
50obtained via a previous call to
51.Fn pthread_key_create .
52Different threads can bind different values to the same key.
53These values are
54typically pointers to blocks of dynamically allocated memory that have been
55reserved for use by the calling thread.
56.Pp
57The effect of calling
58.Fn pthread_setspecific
59with a key value not obtained from
60.Fn pthread_key_create
61or after
62.Fa key
63has been deleted with
64.Fn pthread_key_delete
65is undefined.
66.Pp
67The
68.Fn pthread_setspecific
69function may be called from a thread-specific data destructor function,
70however this may result in lost storage or infinite loops if doing so
71causes non-NULL key values to remain after
72.Bq PTHREAD_DESTRUCTOR_ITERATIONS
73iterations of destructor calls have been made.
74.Sh RETURN VALUES
75If successful, the
76.Fn pthread_setspecific
77function will return zero.
78Otherwise an error number will be returned to
79indicate the error.
80.Sh ERRORS
81The
82.Fn pthread_setspecific
83function will fail if:
84.Bl -tag -width Er
85.It Bq Er ENOMEM
86Insufficient memory exists to associate the value with the
87.Fa key .
88.It Bq Er EINVAL
89The
90.Fa key
91value is invalid.
92.El
93.Sh SEE ALSO
94.Xr pthread_getspecific 3 ,
95.Xr pthread_key_create 3 ,
96.Xr pthread_key_delete 3
97.Sh STANDARDS
98The
99.Fn pthread_setspecific
100function conforms to
101.St -p1003.1-96 .
102