rculfhash: document algorithms

[urcu.git] / urcu / rculfhash.h

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index fab7d82d77ddbcf7ce31759588e1f50b1929614d..b98b4932922e02fab3cd53e6630a46ca3b848a06 100644 (file)
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -4,13 +4,21 @@
 #include <stdint.h>
 #include <urcu-call-rcu.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct _rcu_ht_node {
+       struct rcu_ht_node *next;       /* ptr | DUMMY_FLAG | REMOVED_FLAG */
+       unsigned long reverse_hash;
+};
+
 struct rcu_ht_node {
-       struct rcu_ht_node *next;
+       /* cache-hot for iteration */
+       struct _rcu_ht_node p;          /* needs to be first field */
        void *key;
-       unsigned long hash;
-       unsigned long reverse_hash;
-       unsigned int dummy;
-       void *value;
+       unsigned int key_len;
+       /* cache-cold for iteration */
        struct rcu_head head;
 };
 
@@ -21,36 +29,56 @@ struct rcu_ht;
  * Ensure reader and writer threads are registered as urcu readers.
  */
 
-typedef unsigned long (*ht_hash_fct)(void *hashseed, void *key);
+typedef unsigned long (*ht_hash_fct)(void *key, size_t length,
+                                    unsigned long seed);
+typedef unsigned long (*ht_compare_fct)(void *key1, size_t key1_len,
+                                       void *key2, size_t key2_len);
 
 static inline
-void ht_node_init(struct rcu_ht_node *node, void *key, void *value)
+void ht_node_init(struct rcu_ht_node *node, void *key,
+                 size_t key_len)
 {
        node->key = key;
-       node->value = value;
-       node->dummy = 0;
+       node->key_len = key_len;
 }
 
 /*
  * init_size must be power of two.
  */
 struct rcu_ht *ht_new(ht_hash_fct hash_fct,
-                     void *hashseed,
+                     ht_compare_fct compare_fct,
+                     unsigned long hash_seed,
                      unsigned long init_size,
                      void (*ht_call_rcu)(struct rcu_head *head,
                                void (*func)(struct rcu_head *head)));
 
 int ht_destroy(struct rcu_ht *ht);
+/* Count the number of nodes in the hash table. Call with rcu_read_lock held. */
+void ht_count_nodes(struct rcu_ht *ht,
+               unsigned long *count,
+               unsigned long *removed);
 
 /* Call with rcu_read_lock held. */
-struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key);
+struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len);
 
 /* Call with rcu_read_lock held. */
-int ht_add(struct rcu_ht *ht, struct rcu_ht_node *node);
+void ht_add(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);
 
 void ht_resize(struct rcu_ht *ht, int growth);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _URCU_RCULFHASH_H */