+++ /dev/null
-/*
- * Copyright (c) 2000 by Hewlett-Packard Company. All rights reserved.
- *
- * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
- * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
- *
- * Permission is hereby granted to use or copy this program
- * for any purpose, provided the above notices are retained on all copies.
- * Permission to modify the code and to distribute modified code is granted,
- * provided the above notices are retained, and a notice that the code was
- * modified is included with the above copyright notice.
- */
-
-#if defined(GC_LINUX_THREADS)
-
-#include "private/gc_priv.h" /* For GC_compare_and_exchange, GC_memory_barrier */
-#include "private/specific.h"
-
-static tse invalid_tse = {INVALID_QTID, 0, 0, INVALID_THREADID};
- /* A thread-specific data entry which will never */
- /* appear valid to a reader. Used to fill in empty */
- /* cache entries to avoid a check for 0. */
-
-int PREFIXED(key_create) (tsd ** key_ptr, void (* destructor)(void *)) {
- int i;
- tsd * result = (tsd *)MALLOC_CLEAR(sizeof (tsd));
-
- /* A quick alignment check, since we need atomic stores */
- GC_ASSERT((unsigned long)(&invalid_tse.next) % sizeof(tse *) == 0);
- if (0 == result) return ENOMEM;
- pthread_mutex_init(&(result -> lock), NULL);
- for (i = 0; i < TS_CACHE_SIZE; ++i) {
- result -> cache[i] = &invalid_tse;
- }
-# ifdef GC_ASSERTIONS
- for (i = 0; i < TS_HASH_SIZE; ++i) {
- GC_ASSERT(result -> hash[i] == 0);
- }
-# endif
- *key_ptr = result;
- return 0;
-}
-
-int PREFIXED(setspecific) (tsd * key, void * value) {
- pthread_t self = pthread_self();
- int hash_val = HASH(self);
- volatile tse * entry = (volatile tse *)MALLOC_CLEAR(sizeof (tse));
-
- GC_ASSERT(self != INVALID_THREADID);
- if (0 == entry) return ENOMEM;
- pthread_mutex_lock(&(key -> lock));
- /* Could easily check for an existing entry here. */
- entry -> next = key -> hash[hash_val];
- entry -> thread = self;
- entry -> value = value;
- GC_ASSERT(entry -> qtid == INVALID_QTID);
- /* There can only be one writer at a time, but this needs to be */
- /* atomic with respect to concurrent readers. */
- *(volatile tse **)(key -> hash + hash_val) = entry;
- pthread_mutex_unlock(&(key -> lock));
- return 0;
-}
-
-/* Remove thread-specific data for this thread. Should be called on */
-/* thread exit. */
-void PREFIXED(remove_specific) (tsd * key) {
- pthread_t self = pthread_self();
- unsigned hash_val = HASH(self);
- tse *entry;
- tse **link = key -> hash + hash_val;
-
- pthread_mutex_lock(&(key -> lock));
- entry = *link;
- while (entry != NULL && entry -> thread != self) {
- link = &(entry -> next);
- entry = *link;
- }
- /* Invalidate qtid field, since qtids may be reused, and a later */
- /* cache lookup could otherwise find this entry. */
- entry -> qtid = INVALID_QTID;
- if (entry != NULL) {
- *link = entry -> next;
- /* Atomic! concurrent accesses still work. */
- /* They must, since readers don't lock. */
- /* We shouldn't need a volatile access here, */
- /* since both this and the preceding write */
- /* should become visible no later than */
- /* the pthread_mutex_unlock() call. */
- }
- /* If we wanted to deallocate the entry, we'd first have to clear */
- /* any cache entries pointing to it. That probably requires */
- /* additional synchronization, since we can't prevent a concurrent */
- /* cache lookup, which should still be examining deallocated memory.*/
- /* This can only happen if the concurrent access is from another */
- /* thread, and hence has missed the cache, but still... */
-
- /* With GC, we're done, since the pointers from the cache will */
- /* be overwritten, all local pointers to the entries will be */
- /* dropped, and the entry will then be reclaimed. */
- pthread_mutex_unlock(&(key -> lock));
-}
-
-/* Note that even the slow path doesn't lock. */
-void * PREFIXED(slow_getspecific) (tsd * key, unsigned long qtid,
- tse * volatile * cache_ptr) {
- pthread_t self = pthread_self();
- unsigned hash_val = HASH(self);
- tse *entry = key -> hash[hash_val];
-
- GC_ASSERT(qtid != INVALID_QTID);
- while (entry != NULL && entry -> thread != self) {
- entry = entry -> next;
- }
- if (entry == NULL) return NULL;
- /* Set cache_entry. */
- entry -> qtid = qtid;
- /* It's safe to do this asynchronously. Either value */
- /* is safe, though may produce spurious misses. */
- /* We're replacing one qtid with another one for the */
- /* same thread. */
- *cache_ptr = entry;
- /* Again this is safe since pointer assignments are */
- /* presumed atomic, and either pointer is valid. */
- return entry -> value;
-}
-
-#endif /* GC_LINUX_THREADS */
projects / msp430-gcc.git / blobdiff