TSS(3) FreeBSD Library Functions Manual TSS(3)
NAME
tss - thread-specific storage functions
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <threads.h>
typedef void (*tss_dtor_t) (void *)
int
tss_create(tss_t *key, tss_dtor_t dtor);
void
tss_delete(tss_t key);
void *
tss_get(tss_t key);
int
tss_set(tss_t key, void *val);
#define TSS_DTOR_ITERATIONS /* implementation specified */
DESCRIPTION
There are two groups of storage in C programs:
- local storage,
- global storage.
Multithreaded programs in C add the third group thread-specific storage.
This data is private to thread and every entry of this type has an
associated tss_t opaque key that is global to all threads in the process.
A thread using the tss_t * pointer accesses private data.
The tss_create() function creates a thread-specific storage with the key
handler with optional destructor dtor. If the dtor parameter is not
NULL, then specified appropriate destructor will be called on thread
termination. The destructor is not called if a thread called the
tss_delete() function for the specified key. If, after all the
destructors have been called for all non-NULL values with associated
destructors, there are still some non-NULL values with associated
destructors, then the process is repeated. If, after at least
TSS_DTOR_ITERATIONS iterations of destructor calls for outstanding
non-NULL values, there are still some non-NULL values with associated
destructors, the NetBSD implementation stops calling further destructors.
The thrd_exit(3) function must not be called from a destructor.
The tss_delete() function frees resources used by the thread-specific
storage identified by the key object. This function can be called inside
the dtor destructor, however the destructor is not called by
tss_delete().
The tss_get() and tss_set() functions are used to get and set thread-
specific storage.
RETURN VALUES
The tss_create() function returns thrd_success on success, otherwise
thrd_error on failure.
The tss_delete() function returns no value.
The tss_get() returns pointer to thread-specific storage on success or
NULL on failure.
The tss_set() function returns thrd_success on success, otherwise
thrd_error on failure.
SEE ALSO
pthread_getspecific(3), pthread_key_create(3), threads(3)
STANDARDS
The tss interface conforms to ISO/IEC 9899:2011 ("ISO C11").
HISTORY
This interface first appeared in NetBSD 9.
AUTHORS
Kamil Rytarowski <
[email protected]>
FreeBSD 14.1-RELEASE-p8 October 16, 2016 FreeBSD 14.1-RELEASE-p8