X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfhash.h;h=c03baf41a2b8405fda996ddb633a250a8bcdd89a;hp=ad157bb6a66ecb570f28dd1b627ce89e7ca08a44;hb=0b6aa0018b42d0b101c617ef6c6d34d0f4dd2258;hpb=1475579ca651164ea74eb0c9f727baad991098af

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index ad157bb..c03baf4 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -7,6 +7,7 @@
  * Userspace RCU library - Lock-Free RCU Hash Table
  *
  * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -21,34 +22,50 @@
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Include this file _after_ including your URCU flavor.
  */
 
 #include <stdint.h>
+#include <urcu/compiler.h>
 #include <urcu-call-rcu.h>
+#include <urcu-flavor.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /*
- * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
- * 4-bytes boundaries because the two lower bits are used as flags.
+ * cds_lfht_node: Contains the next pointers and reverse-hash
+ * value required for lookup and traversal of the hash table.
+ *
+ * struct cds_lfht_node should be aligned on 4-bytes boundaries because
+ * the two lower bits are used as flags.
+ *
+ * struct cds_lfht_node can be embedded into a structure (as a field).
+ * caa_container_of() can be used to get the structure from the struct
+ * cds_lfht_node after a lookup.
+ *
+ * The structure which embeds it typically holds the key (or key-value
+ * pair) of the object. The caller code is responsible for calculation
+ * of the hash value for cds_lfht APIs.
  */
-
-struct _cds_lfht_node {
-	struct cds_lfht_node *next;	/* ptr | DUMMY_FLAG | REMOVED_FLAG */
+struct cds_lfht_node {
+	struct cds_lfht_node *next;	/* ptr | BUCKET_FLAG | REMOVED_FLAG */
 	unsigned long reverse_hash;
-};
+} __attribute__((aligned(4)));
 
-struct cds_lfht_node {
-	/* cache-hot for iteration */
-	struct _cds_lfht_node p;          /* needs to be first field */
-	void *key;
-	unsigned int key_len;
-	/* cache-cold for iteration */
-	struct rcu_head head;
+/* cds_lfht_iter: Used to track state while traversing a hash chain. */
+struct cds_lfht_iter {
+	struct cds_lfht_node *node, *next;
 };
 
+static inline
+struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
+{
+	return iter->node;
+}
+
 struct cds_lfht;
 
 /*
@@ -56,102 +73,343 @@ struct cds_lfht;
  * Ensure reader and writer threads are registered as urcu readers.
  */
 
-typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
-					unsigned long seed);
-typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
-					void *key2, size_t key2_len);
+typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
 
 /*
  * cds_lfht_node_init - initialize a hash table node
+ * @node: the node to initialize.
+ *
+ * This function is kept to be eventually used for debugging purposes
+ * (detection of memory corruption).
  */
 static inline
-void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
-			size_t key_len)
+void cds_lfht_node_init(struct cds_lfht_node *node)
 {
-	node->key = key;
-	node->key_len = key_len;
 }
 
+/*
+ * Hash table creation flags.
+ */
+enum {
+	CDS_LFHT_AUTO_RESIZE = (1U << 0),
+	CDS_LFHT_ACCOUNTING = (1U << 1),
+};
+
+struct cds_lfht_mm_type {
+	struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets,
+			unsigned long max_nr_buckets);
+	void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order);
+	void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order);
+	struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
+			unsigned long index);
+};
+
+extern const struct cds_lfht_mm_type cds_lfht_mm_order;
+
+/*
+ * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
+ */
+struct cds_lfht *_cds_lfht_new(unsigned long init_size,
+			unsigned long min_nr_alloc_buckets,
+			unsigned long max_nr_buckets,
+			int flags,
+			const struct cds_lfht_mm_type *mm,
+			const struct rcu_flavor_struct *flavor,
+			pthread_attr_t *attr);
+
 /*
  * cds_lfht_new - allocate a hash table.
+ * @init_size: number of buckets to allocate initially. Must be power of two.
+ * @min_nr_alloc_buckets: the minimum number of allocated buckets.
+ *                        (must be power of two)
+ * @max_nr_buckets: the maximum number of hash table buckets allowed.
+ *                  (must be power of two)
+ * @flags: hash table creation flags (can be combined with bitwise or: '|').
+ *           0: no flags.
+ *           CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
+ *           CDS_LFHT_ACCOUNTING: count the number of node addition
+ *                                and removal in the table
+ * @attr: optional resize worker thread attributes. NULL for default.
  *
- * init_size must be power of two.
  * Return NULL on error.
+ * Note: the RCU flavor must be already included before the hash table header.
+ *
+ * The programmer is responsible for ensuring that resize operation has a
+ * priority equal to hash table updater threads. It should be performed by
+ * specifying the appropriate priority in the pthread "attr" argument, and,
+ * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
+ * this priority level. Having lower priority for call_rcu and resize threads
+ * does not pose any correctness issue, but the resize operations could be
+ * starved by updates, thus leading to long hash table bucket chains.
+ * Threads calling this API are NOT required to be registered RCU read-side
+ * threads. It can be called very early.(before rcu is initialized ...etc.)
  */
-struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
-			cds_lfht_compare_fct compare_fct,
-			unsigned long hash_seed,
-			unsigned long init_size,
-			void (*cds_lfht_call_rcu)(struct rcu_head *head,
-				void (*func)(struct rcu_head *head)),
-			void (*cds_lfht_synchronize_rcu)(void));
+static inline
+struct cds_lfht *cds_lfht_new(unsigned long init_size,
+			unsigned long min_nr_alloc_buckets,
+			unsigned long max_nr_buckets,
+			int flags,
+			pthread_attr_t *attr)
+{
+	return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
+			flags, &cds_lfht_mm_order, &rcu_flavor, attr);
+}
 
 /*
  * cds_lfht_destroy - destroy a hash table.
+ * @ht: the hash table to destroy.
+ * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
+ *        The caller will typically want to free this pointer if dynamically
+ *        allocated. The attr point can be NULL if the caller does not
+ *        need to be informed of the value passed to cds_lfht_new().
  *
  * Return 0 on success, negative error value on error.
+ * Threads calling this API need to be registered RCU read-side threads.
  */
-int cds_lfht_destroy(struct cds_lfht *ht);
+int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
 
 /*
  * cds_lfht_count_nodes - count the number of nodes in the hash table.
+ * @ht: the hash table.
+ * @split_count_before: Sample the node count split-counter before traversal.
+ * @count: Traverse the hash table, count the number of nodes observed.
+ * @removed: Number of logically removed nodes observed during traversal.
+ * @split_count_after: Sample the node count split-counter after traversal.
  *
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
  */
 void cds_lfht_count_nodes(struct cds_lfht *ht,
-			unsigned long *count,
-			unsigned long *removed);
+		long *split_count_before,
+		unsigned long *count,
+		unsigned long *removed,
+		long *split_count_after);
 
 /*
  * cds_lfht_lookup - lookup a node by key.
+ * @ht: the hash table.
+ * @hash: the key hash.
+ * @match: the key match function.
+ * @key: the current node key.
+ * @iter: Node, if found (output). *iter->node set to NULL if not found.
  *
- * Return NULL if not found.
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
  */
-struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
+void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
+		cds_lfht_match_fct match, const void *key,
+		struct cds_lfht_iter *iter);
 
 /*
- * cds_lfht_next - get the next item with same key (after a lookup).
+ * cds_lfht_next_duplicate - get the next item with same key (after a lookup).
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @key: the current node key.
+ * @iter: Node, if found (output). *iter->node set to NULL if not found.
  *
- * Return NULL if no following node exists with same key.
- * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
- * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
+ * Uses an iterator initialized by a lookup.
+ * Sets *iter-node to the following node with same key.
+ * Sets *iter->node to NULL if no following node exists with same key.
+ * RCU read-side lock must be held across cds_lfht_lookup and
+ * cds_lfht_next calls, and also between cds_lfht_next calls using the
+ * node returned by a previous cds_lfht_next.
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
  */
-struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
+void cds_lfht_next_duplicate(struct cds_lfht *ht,
+		cds_lfht_match_fct match, const void *key,
+		struct cds_lfht_iter *iter);
+
+/*
+ * cds_lfht_first - get the first node in the table.
+ * @ht: the hash table.
+ * @iter: First node, if exists (output). *iter->node set to NULL if not found.
+ *
+ * Output in "*iter". *iter->node set to NULL if table is empty.
+ * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ */
+void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
+
+/*
+ * cds_lfht_next - get the next node in the table.
+ * @ht: the hash table.
+ * @iter: Next node, if exists (output). *iter->node set to NULL if not found.
+ *
+ * Input/Output in "*iter". *iter->node set to NULL if *iter was
+ * pointing to the last table node.
+ * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ */
+void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 
 /*
  * cds_lfht_add - add a node to the hash table.
+ * @ht: the hash table.
+ * @hash: the key hash.
+ * @node: the node to add.
  *
+ * This function supports adding redundant keys into the table.
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
  */
-void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
+void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
+		struct cds_lfht_node *node);
 
 /*
  * cds_lfht_add_unique - add a node to hash table, if key is not present.
+ * @ht: the hash table.
+ * @hash: the node's hash.
+ * @match: the key match function.
+ * @key: the node's key.
+ * @node: the node to try adding.
  *
  * Return the node added upon success.
- * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
- * the node passed as parameter should be freed by the caller.
+ * Return the unique node already present upon failure. If
+ * cds_lfht_add_unique fails, the node passed as parameter should be
+ * freed by the caller.
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ *
+ * The semantic of this function is that if only this function is used
+ * to add keys into the table, no duplicated keys should ever be
+ * observable in the table. The same guarantee apply for combination of
+ * add_unique and add_replace (see below).
  */
-struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
+struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+		unsigned long hash,
+		cds_lfht_match_fct match,
+		const void *key,
+		struct cds_lfht_node *node);
 
 /*
- * cds_lfht_remove - remove node from hash table.
+ * cds_lfht_add_replace - replace or add a node within hash table.
+ * @ht: the hash table.
+ * @hash: the node's hash.
+ * @match: the key match function.
+ * @key: the node's key.
+ * @node: the node to add.
  *
- * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
- * lookup and removal.
+ * Return the node replaced upon success. If no node matching the key
+ * was present, return NULL, which also means the operation succeeded.
+ * This replacement operation should never fail.
  * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ * After successful replacement, a grace period must be waited for before
+ * freeing the memory reserved for the returned node.
+ *
+ * The semantic of replacement vs lookups is the following: if lookups
+ * are performed between a key unique insertion and its removal, we
+ * guarantee that the lookups and get next will always find exactly one
+ * instance of the key if it is replaced concurrently with the lookups.
+ *
+ * Providing this semantic allows us to ensure that replacement-only
+ * schemes will never generate duplicated keys. It also allows us to
+ * guarantee that a combination of add_replace and add_unique updates
+ * will never generate duplicated keys.
  */
-int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
+struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
+		unsigned long hash,
+		cds_lfht_match_fct match,
+		const void *key,
+		struct cds_lfht_node *node);
+
+/*
+ * cds_lfht_replace - replace a node pointer to by iter within hash table.
+ * @ht: the hash table.
+ * @old_iter: the iterator position of the node to replace.
+ * @now_node: the new node to try using for replacement.
+ *
+ * Return 0 if replacement is successful, negative value otherwise.
+ * Replacing a NULL old node or an already removed node will fail with a
+ * negative value.
+ * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
+ * RCU read-side lock must be held between lookup and replacement.
+ * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ * After successful replacement, a grace period must be waited for before
+ * freeing the memory reserved for the old node (which can be accessed
+ * with cds_lfht_iter_get_node).
+ *
+ * The semantic of replacement vs lookups is the following: if lookups
+ * are performed between a key unique insertion and its removal, we
+ * guarantee that the lookups and get next will always find exactly one
+ * instance of the key if it is replaced concurrently with the lookups.
+ *
+ * Providing this semantic allows us to ensure that replacement-only
+ * schemes will never generate duplicated keys. It also allows us to
+ * guarantee that a combination of add_replace and add_unique updates
+ * will never generate duplicated keys.
+ */
+int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
+		struct cds_lfht_node *new_node);
+
+/*
+ * cds_lfht_del - remove node pointed to by iterator from hash table.
+ * @ht: the hash table.
+ * @iter: the iterator position of the node to delete.
+ *
+ * Return 0 if the node is successfully removed, negative value
+ * otherwise.
+ * Replacing a NULL node or an already removed node will fail with a
+ * negative value.
+ * Node can be looked up with cds_lfht_lookup and cds_lfht_next.
+ * cds_lfht_iter_get_node.
+ * RCU read-side lock must be held between lookup and removal.
+ * Call with rcu_read_lock held.
+ * Threads calling this API need to be registered RCU read-side threads.
+ * After successful removal, a grace period must be waited for before
+ * freeing the memory reserved for old node (which can be accessed with
+ * cds_lfht_iter_get_node).
+ */
+int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 
 /*
  * cds_lfht_resize - Force a hash table resize
+ * @ht: the hash table.
  * @new_size: update to this hash table size.
+ *
+ * Threads calling this API need to be registered RCU read-side threads.
  */
 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 
+/*
+ * Note: cds_lfht_for_each are safe for element removal during
+ * iteration.
+ */
+#define cds_lfht_for_each(ht, iter, node)				\
+	for (cds_lfht_first(ht, iter),					\
+			node = cds_lfht_iter_get_node(iter);		\
+		node != NULL;						\
+		cds_lfht_next(ht, iter),				\
+			node = cds_lfht_iter_get_node(iter))
+
+#define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node)	\
+	for (cds_lfht_lookup(ht, hash, match, key, iter),		\
+			node = cds_lfht_iter_get_node(iter);		\
+		node != NULL;						\
+		cds_lfht_next_duplicate(ht, match, key, iter),		\
+			node = cds_lfht_iter_get_node(iter))
+
+#define cds_lfht_for_each_entry(ht, iter, pos, member)			\
+	for (cds_lfht_first(ht, iter),					\
+			pos = caa_container_of(cds_lfht_iter_get_node(iter), \
+					typeof(*(pos)), member);	\
+		&(pos)->member != NULL;					\
+		cds_lfht_next(ht, iter),				\
+			pos = caa_container_of(cds_lfht_iter_get_node(iter), \
+					typeof(*(pos)), member))
+
+#define cds_lfht_for_each_entry_duplicate(ht, hash, match, key,		\
+				iter, pos, member)			\
+	for (cds_lfht_lookup(ht, hash, match, key, iter),		\
+			pos = caa_container_of(cds_lfht_iter_get_node(iter), \
+					typeof(*(pos)), member);	\
+		&(pos)->member != NULL;					\
+		cds_lfht_next_duplicate(ht, match, key, iter),		\
+			pos = caa_container_of(cds_lfht_iter_get_node(iter), \
+					typeof(*(pos)), member))
+
 #ifdef __cplusplus
 }
 #endif