tis_key_create - Generates a unique thread-specific data key.
Standard C Library (libc.so, libc.a)
void (*destructor)(void *));
Address of a variable that receives the key value. This value is used in calls to tis_getspecific(3) and tis_setspecific(3) to get and set the value associated with this key. Address of a routine that is called to destroy the context value when a thread terminates with a non-NULL value for the key. Note that this argument is used only when threads are present.
This routine generates a unique thread-specific data key. The key argument points to an opaque object used to locate data.
This routine generates and returns a new key value. The key reserves a cell. Each call to this routine creates a new cell that is unique within an application invocation. Keys must be generated from initialization code that is guaranteed to be called only once within each process. (See the tis_once(3) description for more information.)
Your program can associate an optional destructor function with each key. At thread exit, if a key has a non-NULL destructor function pointer, and the thread has a non-NULL value associated with that key, the function pointed to is called with the current associated value as its sole argument. The order in which data destructors are called at thread termination is undefined.
When threads are present, keys and any corresponding data are thread specific; they enable the context to be maintained on a per-thread basis. For more information about the use of tis_key_create(3) in a threaded environment, refer to the pthread_key_create(3) description.
DECthreads imposes a maximum number of thread-specific data keys, equal to the symbolic constant PTHREAD_KEYS_MAX.
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The system lacked the necessary resources to create another thread-specific data key, or the limit on the total number of keys per process (PTHREAD_KEYS_MAX) has been exceeded. Insufficient memory exists to create the key. Invalid argument.
Functions: tis_getspecific(3), tis_key_delete(3), tis_once(3), tis_setspecific(3)
Manuals: Guide to DECthreads and Programmer's Guide