PTHREAD_GETSPECIFIC(3C) Standard C Library Functions
NAME
pthread_getspecific, pthread_setspecific - manage thread-specific
data
SYNOPSIS
cc -mt [
flag... ]
file... -lpthread [
library... ]
#include <pthread.h>
int pthread_setspecific(
pthread_key_t key,
const void *value);
void *pthread_getspecific(
pthread_key_t key);
DESCRIPTION
The
pthread_setspecific() function associates a thread-specific
value with a
key obtained by way of a previous call to
pthread_key_create(). Different threads may bind different values to
the same key. These values are typically pointers to blocks of
dynamically allocated memory that have been reserved for use by the
calling thread.
The
pthread_getspecific() function returns the value currently bound
to the specified
key on behalf of the calling thread.
The effect of calling
pthread_setspecific() or
pthread_getspecific() with a
key value not obtained from
pthread_key_create() or after
key has been deleted with
pthread_key_delete() is undefined.
Both
pthread_setspecific() and
pthread_getspecific() may be called
from a thread-specific data destructor function. However, calling
pthread_setspecific() from a destructor may result in lost storage or
infinite loops.
RETURN VALUES
The
pthread_getspecific() function returns 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.
Upon successful completion, the
pthread_setspecific() function
returns
0. Otherwise, an error number is returned to indicate the
error.
ERRORS
The
pthread_setspecific() function will fail if:
ENOMEM Insufficient memory exists to associate the value with the
key.
The
pthread_setspecific() function may fail if:
EINVAL The key value is invalid.
The
pthread_getspecific() function does not return errors.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+
SEE ALSO
pthread_key_create(3C),
attributes(7),
standards(7) March 23, 2005 PTHREAD_GETSPECIFIC(3C)
