tss_delete

 

C

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Concurrency support (C11)

Technical Specifications

Symbol index

 

Concurrency 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    Atomic operations atomic_init ATOMIC_VAR_INIT (until C23) ATOMIC_***_LOCK_FREE atomic_is_lock_free atomic_store atomic_load atomic_exchange atomic_compare_exchange atomic_fetch_add atomic_fetch_sub atomic_fetch_or atomic_fetch_xor atomic_fetch_and

Atomic flags atomic_flag ATOMIC_FLAG_INIT atomic_flag_test_and_set atomic_flag_clear Memory ordering memory_order kill_dependency atomic_thread_fence atomic_signal_fence 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>
void tss_delete( tss_t tss_id );		(since C11)

Destroys the thread-specific storage identified by tss_id.

The destructor, if one was registered by tss_create, is not called (they are only called at thread exit, either by thrd_exit or by returning from the thread function), it is the responsibility of the programmer to ensure that every thread that is aware of tss_id performed all necessary cleanup, before the call to tss_delete is made.

If tss_delete is called while another thread is executing destructors for tss_id, it's unspecified whether this changes the number of invocations to the associated destructor.

If tss_delete is called while the calling thread is executing destructors, then the destructor associated with tss_id will not be executed again on this thread.

Parameters

tss_id

-

thread-specific storage key previously returned by tss_create and not yet deleted by tss_delete

Return value

(none)

Notes

The POSIX equivalent of this function is pthread_key_delete.

The reason tss_delete never calls destructors is that the destructors (called at thread exit) are normally intended to be executed by the same thread that originally set the value (via tss_set) that the destructor will be dealing with, and may even rely on the values of that or other thread-specific data as seen by that thread. The thread executing tss_delete has no access to other threads' TSS. Even if it were possible to call the destructor for each thread's own value associated with tss_id, tss_delete would have to synchronize with every thread if only to examine whether the value of this TSS in that thread is null (destructors are only called against non-null values).

References

• C17 standard (ISO/IEC 9899:2018):

• 7.26.6.2 The tss_delete function (p: 282)

• C11 standard (ISO/IEC 9899:2011):

• 7.26.6.2 The tss_delete function (p: 386)