X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=be995dfeaf5ef70795a6fd74a7bc34f4ced558c6;hp=2e338f132e66bb5c6a1271f9cdf2bc8730055aea;hb=3fb86f26cfea354e44be1099642fc88436e3edf3;hpb=0d14ceb26e0ff3e1d6f86cf3ec9674ee3b16e96f

diff --git a/rculfhash.c b/rculfhash.c
index 2e338f1..be995df 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -716,6 +716,27 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
 	return v;
 }
 
+static
+struct _cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
+		unsigned long hash)
+{
+	unsigned long index, order;
+
+	assert(size > 0);
+	index = hash & (size - 1);
+	/*
+	 * equivalent to get_count_order_ulong(index + 1), but optimizes
+	 * away the non-existing 0 special-case for
+	 * get_count_order_ulong.
+	 */
+	order = fls_ulong(index);
+
+	dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
+		   hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1)));
+
+	return &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+}
+
 /*
  * Remove all logically deleted nodes from a bucket up to a certain node key.
  */
@@ -766,13 +787,12 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node
 static
 int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
 		struct cds_lfht_node *old_node,
-		struct cds_lfht_node *ret_next,
+		struct cds_lfht_node *old_next,
 		struct cds_lfht_node *new_node)
 {
-	struct cds_lfht_node *dummy, *old_next;
+	struct cds_lfht_node *dummy, *ret_next;
 	struct _cds_lfht_node *lookup;
 	int flagged = 0;
-	unsigned long hash, index, order;
 
 	if (!old_node)	/* Return -ENOENT if asked to replace NULL node */
 		goto end;
@@ -782,9 +802,8 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
 	assert(!is_removed(new_node));
 	assert(!is_dummy(new_node));
 	assert(new_node != old_node);
-	do {
+	for (;;) {
 		/* Insert after node to be replaced */
-		old_next = ret_next;
 		if (is_removed(old_next)) {
 			/*
 			 * Too late, the old node has been removed under us
@@ -807,7 +826,10 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
 		 */
 		ret_next = uatomic_cmpxchg(&old_node->p.next,
 			      old_next, flag_removed(new_node));
-	} while (ret_next != old_next);
+		if (ret_next == old_next)
+			break;
+		old_next = ret_next;
+	}
 
 	/* We performed the replacement. */
 	flagged = 1;
@@ -817,11 +839,7 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
 	 * lookup for the node, and remove it (along with any other
 	 * logically removed node) if found.
 	 */
-	hash = bit_reverse_ulong(old_node->p.reverse_hash);
-	assert(size > 0);
-	index = hash & (size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+	lookup = lookup_bucket(ht, size, bit_reverse_ulong(old_node->p.reverse_hash));
 	dummy = (struct cds_lfht_node *) lookup;
 	_cds_lfht_gc_bucket(dummy, new_node);
 end:
@@ -844,9 +862,8 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 				enum add_mode mode, int dummy)
 {
 	struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
-			*dummy_node, *return_node;
+			*return_node;
 	struct _cds_lfht_node *lookup;
-	unsigned long hash, index, order;
 
 	assert(!is_dummy(node));
 	assert(!is_removed(node));
@@ -855,7 +872,7 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 		node->p.next = flag_dummy(get_end());
 		return node;	/* Initial first add (head) */
 	}
-	hash = bit_reverse_ulong(node->p.reverse_hash);
+	lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash));
 	for (;;) {
 		uint32_t chain_len = 0;
 
@@ -863,9 +880,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 		 * iter_prev points to the non-removed node prior to the
 		 * insert location.
 		 */
-		index = hash & (size - 1);
-		order = get_count_order_ulong(index + 1);
-		lookup = &ht->t.tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)];
 		iter_prev = (struct cds_lfht_node *) lookup;
 		/* We can always skip the dummy node initially */
 		iter = rcu_dereference(iter_prev->p.next);
@@ -875,11 +889,15 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 				goto insert;
 			if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
 				goto insert;
+			/* dummy node is the first node of the identical-hash-value chain */
+			if (dummy && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash)
+				goto insert;
 			next = rcu_dereference(clear_flag(iter)->p.next);
 			if (unlikely(is_removed(next)))
 				goto gc_node;
 			if ((mode == ADD_UNIQUE || mode == ADD_REPLACE)
 			    && !is_dummy(next)
+			    && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash
 			    && !ht->compare_fct(node->key, node->key_len,
 						clear_flag(iter)->key,
 						clear_flag(iter)->key_len)) {
@@ -917,7 +935,7 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 				return_node = NULL;
 			else	/* ADD_DEFAULT and ADD_UNIQUE */
 				return_node = node;
-			goto gc_end;
+			goto end;
 		}
 
 	replace:
@@ -939,13 +957,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 		(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
 		/* retry */
 	}
-gc_end:
-	/* Garbage collect logically removed nodes in the bucket */
-	index = hash & (size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
-	dummy_node = (struct cds_lfht_node *) lookup;
-	_cds_lfht_gc_bucket(dummy_node, node);
 end:
 	return return_node;
 }
@@ -958,7 +969,6 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
 	struct cds_lfht_node *dummy, *next, *old;
 	struct _cds_lfht_node *lookup;
 	int flagged = 0;
-	unsigned long hash, index, order;
 
 	if (!node)	/* Return -ENOENT if asked to delete NULL node */
 		goto end;
@@ -989,11 +999,7 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
 	 * the node, and remove it (along with any other logically removed node)
 	 * if found.
 	 */
-	hash = bit_reverse_ulong(node->p.reverse_hash);
-	assert(size > 0);
-	index = hash & (size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+	lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash));
 	dummy = (struct cds_lfht_node *) lookup;
 	_cds_lfht_gc_bucket(dummy, node);
 end:
@@ -1318,17 +1324,13 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
 {
 	struct cds_lfht_node *node, *next, *dummy_node;
 	struct _cds_lfht_node *lookup;
-	unsigned long hash, reverse_hash, index, order, size;
+	unsigned long hash, reverse_hash, size;
 
 	hash = ht->hash_fct(key, key_len, ht->hash_seed);
 	reverse_hash = bit_reverse_ulong(hash);
 
 	size = rcu_dereference(ht->t.size);
-	index = hash & (size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)];
-	dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
-		   hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1)));
+	lookup = lookup_bucket(ht, size, hash);
 	dummy_node = (struct cds_lfht_node *) lookup;
 	/* We can always skip the dummy node initially */
 	node = rcu_dereference(dummy_node->p.next);
@@ -1345,6 +1347,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
 		next = rcu_dereference(node->p.next);
 		if (likely(!is_removed(next))
 		    && !is_dummy(next)
+		    && clear_flag(node)->p.reverse_hash == reverse_hash
 		    && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
 				break;
 		}