From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 7 Jul 2011 15:48:34 +0000 (-0400)
Subject: rculfhash: update add_unique api
X-Git-Tag: v0.7.0~43^2~211
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=18117871130163ec2b2fc73fda288b9ba26cd435;p=urcu.git

rculfhash: update add_unique api

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/rculfhash.c b/rculfhash.c
index 1ccd3f1..556ec36 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -234,14 +234,16 @@ void _ht_gc_bucket(struct rcu_ht_node *dummy, struct rcu_ht_node *node)
 }
 
 static
-int _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node,
-	     int unique)
+struct rcu_ht_node *_ht_add(struct rcu_ht *ht, struct rcu_table *t,
+			    struct rcu_ht_node *node, int unique)
 {
 	struct rcu_ht_node *iter_prev, *dummy, *iter, *next;
 	unsigned long hash;
 
-	if (!t->size)
-		return 0;
+	if (!t->size) {
+		assert(node->dummy);
+		return node;	/* Initial first add (head) */
+	}
 	hash = bit_reverse_ulong(node->reverse_hash);
 	for (;;) {
 		uint32_t chain_len = 0;
@@ -267,7 +269,7 @@ int _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node,
 			    && !ht->compare_fct(node->key, node->key_len,
 						clear_flag(iter)->key,
 						clear_flag(iter)->key_len))
-				return -EEXIST;
+				return clear_flag(iter);
 			/* Only account for identical reverse hash once */
 			if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash)
 				check_resize(ht, t, ++chain_len);
@@ -293,7 +295,7 @@ gc_end:
 	/* Garbage collect logically removed nodes in the bucket */
 	dummy = rcu_dereference(t->tbl[hash & (t->size - 1)]);
 	_ht_gc_bucket(dummy, node);
-	return 0;
+	return node;
 }
 
 static
@@ -423,7 +425,7 @@ void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node)
 	(void) _ht_add(ht, t, node, 0);
 }
 
-int ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node)
+struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node)
 {
 	struct rcu_table *t;
 	unsigned long hash;
diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
index e8c51d8..16374d9 100644
--- a/tests/test_urcu_hash.c
+++ b/tests/test_urcu_hash.c
@@ -387,7 +387,7 @@ void free_node_cb(struct rcu_head *head)
 
 void *thr_writer(void *_count)
 {
-	struct rcu_ht_node *node;
+	struct rcu_ht_node *node, *ret_node;
 	struct wr_count *count = _count;
 	int ret;
 
@@ -410,9 +410,9 @@ void *thr_writer(void *_count)
 			ht_node_init(node,
 				(void *)(unsigned long)(rand_r(&rand_lookup) % RAND_POOL),
 				sizeof(void *));
-			ret = ht_add_unique(test_ht, node);
+			ret_node = ht_add_unique(test_ht, node);
 			rcu_read_unlock();
-			if (ret) {
+			if (ret_node != node) {
 				free(node);
 				nr_addexist++;
 			} else
@@ -569,6 +569,7 @@ int main(int argc, char **argv)
 	count_writer = malloc(sizeof(*count_writer) * nr_writers);
 	test_ht = ht_new(test_hash, test_compare, 0x42UL,
 			 HASH_SIZE, call_rcu);
+
 	next_aff = 0;
 
 	for (i = 0; i < nr_readers; i++) {
diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index bec7776..6bb1ccf 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -58,8 +58,13 @@ struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len);
 /* Call with rcu_read_lock held. */
 void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node);
 
-/* Call with rcu_read_lock held. */
-int ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node);
+/*
+ * Call with rcu_read_lock held.
+ * Returns the node added upon success.
+ * Returns the unique node already present upon failure. If ht_add_unique fails,
+ * the node passed as parameter should be freed by the caller.
+ */
+struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node);
 
 /* Call with rcu_read_lock held. */
 int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node);