pthread_getspecific¶

Synopsis¶

#include <pthread.h>

void *pthread_getspecific(pthread_key_t key);

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

Status¶

Implemented

Conformance¶

IEEE Std 1003.1-2017

Description¶

The pthread_getspecific() function shall return the value currently bound to the specified key on behalf of the calling thread.

The pthread_setspecific() function shall associate a thread-specific value with a key obtained via 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 effect of calling pthread_getspecific() or pthread_setspecific() with a key value not obtained from pthread_key_create() or after key has been deleted with pthread_key_delete() is undefined.

Both pthread_getspecific() and pthread_setspecific() may be called from a thread-specific data destructor function. A call to pthread_getspecific() for the thread-specific data key being destroyed shall return the value NULL, unless the value is changed (after the destructor starts) by a call to pthread_setspecific(). Calling pthread_setspecific() from a thread-specific data destructor routine may result either in lost storage (after at least PTHREAD_DESTRUCTOR_ITERATIONS attempts at destruction) or in an infinite loop.

Return value¶

The pthread_getspecific() function shall 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 shall be returned.

If successful, the pthread_setspecific() function shall return zero; otherwise, an error number shall be returned to indicate the error.

Errors¶

No errors are returned from pthread_getspecific().

The pthread_setspecific() function shall fail if:

ENOMEM - Insufficient memory exists to associate the non-NULL value with the key.

The pthread_setspecific() function shall not return an error code of EINTR.

POSIX deviations¶

No POSIX deviations discovered.