tss_create

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

Thread support library

Threads
thrd_create thrd_equal thrd_current thrd_sleep thrd_yield thrd_exit	thrd_detach thrd_join thrd_successthrd_timedoutthrd_busythrd_nomemthrd_error
Mutual exclusion
mtx_init mtx_lock mtx_timedlock mtx_trylock call_once	mtx_unlock mtx_destroy mtx_plainmtx_recursivemtx_timed
Condition variables
cnd_init cnd_signal cnd_broadcast	cnd_wait cnd_timedwait cnd_destroy
Thread-local storage
thread_local TSS_DTOR_ITERATIONS tss_create	tss_get tss_set tss_delete

Defined in header <threads.h>
int tss_create( tss_t* tss_key, tss_dtor_t destructor );		(since C11)

Creates new thread-specific storage key and stores it in the object pointed to by tss_key. Although the same key value may be used by different threads, the values bound to the key by tss_set are maintained on a per-thread basis and persist for the life of the calling thread.

The value NULL is associated with the newly created key in all existing threads, and upon thread creation, the values associated with all TSS keys is initialized to NULL.

If destructor is not a null pointer, then also associates the destructor which is called when the storage is released by thrd_exit (but not by tss_delete and not at program termination by exit).

A call to tss_create from within a thread-specific storage destructor results in undefined behavior.

Parameters

tss_key	-	pointer to memory location to store the new thread-specific storage key
destructor	-	pointer to a function to call at thread exit

Notes

The POSIX equivalent of this function is pthread_key_create

Return value

thrd_success if successful, thrd_error otherwise.

Example

int thread_func(void *arg) {
    tss_t key;
    if (thrd_success == tss_create(&key, free)) {
        tss_set(key, malloc(4)); // stores a pointer on TSS
        // ...
    }
} // calls free() for the pointer stored on TSS

References

• C11 standard (ISO/IEC 9899:2011):

• 7.26.6.1 The tss_create function (p: 386)