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authorrpj <rpj>1999-01-03 16:41:14 +0000
committerrpj <rpj>1999-01-03 16:41:14 +0000
commit5ab9f5892826bb1c4e45b4dcb2692d4eb2f813f1 (patch)
tree055390c239a2f7cefdde4360a5f0f0096be19930 /tsd.c
parent63d8161801576f3acd5169b472946f4a687c4728 (diff)
Mon Jan 4 11:23:40 1999 Ross Johnson <rpj@ixobrychus.canberra.edu.au>bossom-merge-99-01-04bossom-merge-98-12-08
* all: No code changes, just cleanup. - remove #if 0 /* Pre Bossom */ enclosed code. - Remove some redundant #includes. * pthread.h: Update implemented/unimplemented routines list. * Tag the bossom merge branch getting ready to merge back to main trunk.
Diffstat (limited to 'tsd.c')
-rw-r--r--tsd.c203
1 files changed, 0 insertions, 203 deletions
diff --git a/tsd.c b/tsd.c
index 6ea2eb0..72a03ea 100644
--- a/tsd.c
+++ b/tsd.c
@@ -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 */