diff options
Diffstat (limited to 'tsd.c')
| -rw-r--r-- | tsd.c | 203 |
1 files changed, 0 insertions, 203 deletions
@@ -5,49 +5,6 @@ * POSIX thread functions which implement thread-specific data (TSD). */ -/* - * Why we can't use Win32 TLS - * -------------------------- - * - * In a word: Destructors - * - * POSIX 1003.1 1996, Section 17 allows for optional destructor functions - * to be associated with each key value. - * - * This is my (revised) understanding of how destructors work: - * - * A key is created by a single thread, which then provides in every - * existing thread a TSD matching the same key, but initialised - * to NULL. Each new thread will also get a matching key with value NULL. - * The creating thread can optionally associate a function, called a - * destructor, with the key. - * - * When each thread exits, it calls the destructor function, which - * will then perform an action on that threads key value - * only. (Previously I thought that only the key creating thread ran - * the destructor on the key in all threads. That proposition is - * sounding scarier by the minute.) - * - * SOME APPROACHES TO MANAGING TSD MEMORY - * - * We could simply allocate enough memory on process startup to hold - * all possible data for all possible threads. - * - * We could allocate memory for just a table to hold a single pointer - * for each of POSIX_THREAD_KEYS_MAX keys. pthread_key_create() could then - * allocate space for POSIX_THREADS_MAX key values in one hit and store - * the location of the array in the first table. - * - * The standard also suggests that each thread might store key/value pairs - * on its private stack. This seems like a good idea. I had concerns about - * memory leaks and key re-use if a key was deleted, but the standard talks - * at length on this and basically says it's up to the application to - * make sure everything goes smoothly here, making sure that proper cleanup - * is done before a key is deleted. (section B.17.1.3 in particular) - * - * One more thing to note: destructors must never be called on deleted keys. - */ - #include "pthread.h" #include "implement.h" @@ -351,163 +308,3 @@ pthread_getspecific (pthread_key_t key) /* </JEB> */ - -#if 0 /* Pre Bossom */ - -#include <errno.h> - -#include "pthread.h" -#include "implement.h" - -int -pthread_key_create(pthread_key_t *key, void (*destructor)(void *)) -{ - pthread_key_t k; - int ret = 0; - - /* CRITICAL SECTION */ - pthread_mutex_lock(&_pthread_tsd_mutex); - - if (_pthread_key_reuse_top >= 0) - { - k = _pthread_key_reuse[_pthread_key_reuse_top--]; - } - else - { - if (_pthread_key_virgin_next < PTHREAD_KEYS_MAX) - { - k = _pthread_key_virgins[_pthread_key_virgin_next++]; - } - else - { - return EAGAIN; - } - } - - /* FIXME: This needs to be implemented as a list plus a re-use stack as for - thread IDs. _pthread_destructor_run_all() then needs to be changed - to push keys onto the re-use stack. - */ - - _pthread_tsd_key_table[k].in_use = 0; - _pthread_tsd_key_table[k].status = _PTHREAD_TSD_KEY_INUSE; - _pthread_tsd_key_table[k].destructor = destructor; - - pthread_mutex_unlock(&_pthread_tsd_mutex); - /* END CRITICAL SECTION */ - - *key = k; - - return ret; -} - -int -pthread_setspecific(pthread_key_t key, void *value) -{ - void ** keys; - int inuse; - - /* CRITICAL SECTION */ - pthread_mutex_lock(&_pthread_tsd_mutex); - - inuse = (_pthread_tsd_key_table[key].status == _PTHREAD_TSD_KEY_INUSE); - - pthread_mutex_unlock(&_pthread_tsd_mutex); - /* END CRITICAL SECTION */ - - if (! inuse) - return EINVAL; - - keys = (void **) TlsGetValue(_pthread_TSD_keys_TlsIndex); - - if (keys[key] != NULL) - { - if (value == NULL) - { - /* Key is no longer in use by this thread. */ - _pthread_tsd_key_table[key].in_use--; - } - } - else - { - if (value != NULL) - { - /* Key is now in use by this thread. */ - _pthread_tsd_key_table[key].in_use++; - } - } - - keys[key] = value; - - return 0; -} - -void * -pthread_getspecific(pthread_key_t key) -{ - void ** keys; - int inuse; - - /* CRITICAL SECTION */ - pthread_mutex_lock(&_pthread_tsd_mutex); - - inuse = (_pthread_tsd_key_table[key].status == _PTHREAD_TSD_KEY_INUSE); - - pthread_mutex_unlock(&_pthread_tsd_mutex); - /* END CRITICAL SECTION */ - - if (! inuse) - return (void *) NULL; - - keys = (void **) TlsGetValue(_pthread_TSD_keys_TlsIndex); - return keys[key]; -} - -/* - pthread_key_delete: - - ANSI/IEEE Std 1003.1, 1996 Edition - - Section 17.1.3.2 - - This function deletes a thread-specific data key previously returned by - pthread_key_create(). The thread specific data values associated with - "key" need not be NULL at the time pthread_key_delete() is called. It is - the responsibility of the application to free any application storage - or perform any cleanup actions for data structures related to the deleted - key or associated thread-specific data in any threads; this cleanup - can be done either before or after pthread_key_delete() is called. Any - attempt to use "key" following the call to pthread_key_delete() - results in undefined behaviour. - - The pthread_key_delete() function shall be callable from within - destructor functions. No destructor functions shall be invoked by - pthread_key_delete(). Any destructor function that may have been associated - with "key" shall no longer be called upon thread exit. - */ - -int -pthread_key_delete(pthread_key_t key) -{ - int ret = 0; - - /* CRITICAL SECTION */ - pthread_mutex_lock(&_pthread_tsd_mutex); - - if (_pthread_tsd_key_table[key].status != _PTHREAD_TSD_KEY_INUSE) - { - ret = EINVAL; - } - else - { - _pthread_tsd_key_table[key].status = _PTHREAD_TSD_KEY_DELETED; - _pthread_tsd_key_table[key].destructor = NULL; - } - - pthread_mutex_unlock(&_pthread_tsd_mutex); - /* END CRITICAL SECTION */ - - return ret; -} - -#endif /* Pre Bossom */ |