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
typically 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 number 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”).