Manual Pages  — PTHREAD_SETSPECIFIC

pthread_setspecific – set a thread-specific data value

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES ERRORS SEE ALSO STANDARDS

POSIX Threads Library (libpthread, -lpthread)

#include <pthread.h>

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

The pthread_setspecific() function associates a thread-specific value with a key obtained via a previous call to pthread_key_create(). Different threads can 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_setspecific() with a key value not obtained from pthread_key_create() or after key has been deleted with pthread_key_delete() is undefined.

The pthread_setspecific() function may be called from a thread-specific data destructor function, however this may result in lost storage or infinite loops if doing so causes non-NULL key values to remain after [PTHREAD_DESTRUCTOR_ITERATIONS] iterations of destructor calls have been made.

If successful, the pthread_setspecific() function will return zero. Otherwise an error number will be returned to indicate the error.

The pthread_setspecific() function will fail if:

[ENOMEM]
	Insufficient memory exists to associate the value with the key.
[EINVAL]
	The key value is invalid.

The pthread_setspecific() function conforms to IEEE Std 1003.1-96 ("POSIX.1").