pthread_getspecific(3) - NetBSD Manual Pages

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PTHREAD_GETSPECIFIC(3)  NetBSD Library Functions Manual PTHREAD_GETSPECIFIC(3)


NAME

     pthread_getspecific -- thread-specific data value


LIBRARY

     POSIX Threads Library (libpthread, -lpthread)


SYNOPSIS

     #include <pthread.h>

     void *
     pthread_getspecific(pthread_key_t key);

     int
     pthread_setspecific(pthread_key_t key, const void *value);


DESCRIPTION

     The pthread_getspecific() function returns the value currently bound to
     the specified key on behalf of the calling thread.  Conversely, the
     pthread_setspecific() function associates a thread-specific value with a
     key obtained via a previous call to pthread_key_create(3).  Different
     threads have different values bound to each key.  These values are typi-
     cally pointers to blocks of dynamically allocated memory that have been
     reserved for use by the calling thread.

     Undefined behavior may follow if either function is called with a key
     value not obtained from pthread_key_create(3), or if the call is made
     after key has been deleted with pthread_key_delete(3).  It is possible to
     call either function from a thread-specific data destructor function.
     Note however that this is not well defined for the pthread_setspecific()
     function; lost storage or infinite loops may occur.


RETURN VALUES

     The pthread_getspecific() function will return the thread-specific data
     value associated with the given key.  If no thread-specific data value is
     associated with key, then the value NULL is returned.  If successful, the
     pthread_setspecific() function will return zero.  Otherwise an error num-
     ber will be returned to indicate the error.


ERRORS

     No errors are defined for either function.


SEE ALSO

     pthread_key_create(3)


STANDARDS

     These functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

NetBSD 6.1                       July 9, 2010                       NetBSD 6.1