rculfhash: remove hash from nodes

Shrink node size, can get it quickly by reversing the reverse_hash.

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

diff --git a/rculfhash.c b/rculfhash.c
index 0d8c5d6150ae9fa9eecc05d46b96e2ff4e6ef44c..11c0077977f327e5437a13d050f8eceb6e7a6a6b 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -238,9 +238,11 @@ int _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;
+       hash = bit_reverse_ulong(node->reverse_hash);
        for (;;) {
                uint32_t chain_len = 0;
 
@@ -248,7 +250,7 @@ int _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node,
                 * iter_prev points to the non-removed node prior to the
                 * insert location.
                 */
-               iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]);
+               iter_prev = rcu_dereference(t->tbl[hash & (t->size - 1)]);
                /* We can always skip the dummy node initially */
                iter = rcu_dereference(iter_prev->next);
                assert(iter_prev->reverse_hash <= node->reverse_hash);
@@ -283,7 +285,7 @@ int _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node,
        }
 gc_end:
        /* Garbage collect logically removed nodes in the bucket */
-       dummy = rcu_dereference(t->tbl[node->hash & (t->size - 1)]);
+       dummy = rcu_dereference(t->tbl[hash & (t->size - 1)]);
        _ht_gc_bucket(dummy, node);
        return 0;
 }
@@ -293,6 +295,7 @@ int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node)
 {
        struct rcu_ht_node *dummy, *next, *old;
        int flagged = 0;
+       unsigned long hash;
 
        /* logically delete the node */
        old = rcu_dereference(node->next);
@@ -313,7 +316,8 @@ int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node)
         * the node, and remove it (along with any other logically removed node)
         * if found.
         */
-       dummy = rcu_dereference(t->tbl[node->hash & (t->size - 1)]);
+       hash = bit_reverse_ulong(node->reverse_hash);
+       dummy = rcu_dereference(t->tbl[hash & (t->size - 1)]);
        _ht_gc_bucket(dummy, node);
 end:
        /*
@@ -340,7 +344,6 @@ void init_table(struct rcu_ht *ht, struct rcu_table *t,
                        t->size = i;
                t->tbl[i] = calloc(1, sizeof(struct rcu_ht_node));
                t->tbl[i]->dummy = 1;
-               t->tbl[i]->hash = i;
                t->tbl[i]->reverse_hash = bit_reverse_ulong(i);
                (void) _ht_add(ht, t, t->tbl[i], 0);
        }
@@ -391,9 +394,9 @@ struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len)
                        node = NULL;
                        break;
                }
-               if (!ht->compare_fct(node->key, node->key_len, key, key_len)) {
-                       if (likely(!is_removed(rcu_dereference(node->next)))
-                           && likely(!node->dummy))
+               if (likely(!is_removed(rcu_dereference(node->next)))
+                   && !node->dummy
+                   && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
                                break;
                }
                node = clear_flag(rcu_dereference(node->next));
@@ -405,9 +408,10 @@ struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len)
 void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node)
 {
        struct rcu_table *t;
+       unsigned long hash;
 
-       node->hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
-       node->reverse_hash = bit_reverse_ulong((unsigned long) node->hash);
+       hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
+       node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
 
        t = rcu_dereference(ht->t);
        (void) _ht_add(ht, t, node, 0);
@@ -416,9 +420,10 @@ void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node)
 int ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node)
 {
        struct rcu_table *t;
+       unsigned long hash;
 
-       node->hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
-       node->reverse_hash = bit_reverse_ulong((unsigned long) node->hash);
+       hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
+       node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
 
        t = rcu_dereference(ht->t);
        return _ht_add(ht, t, node, 1);

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index 2e50beb27a5711c855a03f4689e11ae8c033e8ea..bec7776c2fd6f3f2f2eb58c9c058dafd18e2d3f0 100644 (file)
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -12,7 +12,6 @@ struct rcu_ht_node {
        unsigned int key_len;
        unsigned int dummy;
        /* cache-cold for iteration */
-       unsigned long hash;
        struct rcu_head head;
 };