rculfhash: extract compare_fct and hash_fct from the hash table
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Sat, 5 Nov 2011 13:01:09 +0000 (09:01 -0400)
committerMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Sat, 5 Nov 2011 13:01:09 +0000 (09:01 -0400)
Leave the compare_fct and hash_fct to the caller, which can therefore
become the only one which needs to know the layout of struct
cds_lfht_node (except for the _cds_lfht_node part).

This will enable us to remove the cds_lfht_node structure from the hash
table (moving it entirely to the caller), replacing it by
_cds_lfht_node, which is really the only part the hash table needs to
know about.

Use-cases that can benefit from this extra flexibility:

>> Sometimes the caller don't have the key or the keys which are big
>> are saved separated. Example: file server
>> Or key comparation is too slow.
>> Or caller just need approximate lookup.
>> Or caller want to compare keys with different strategies for
>> performance.

Suggested-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
rculfhash.c
tests/test_urcu_hash.c
urcu/rculfhash.h

index 600feecfa8f4f8230eede1683cf79cff14a0333f..53ecaacb310ee7b0b9af92dad824a017063be22a 100644 (file)
@@ -267,8 +267,6 @@ struct rcu_table {
  */
 struct cds_lfht {
        struct rcu_table t;
-       cds_lfht_hash_fct hash_fct;
-       cds_lfht_compare_fct compare_fct;
        unsigned long min_alloc_order;
        unsigned long min_alloc_size;
        unsigned long hash_seed;
@@ -320,6 +318,7 @@ struct partition_resize_work {
 
 static
 void _cds_lfht_add(struct cds_lfht *ht,
+               cds_lfht_match_fct match,
                unsigned long size,
                struct cds_lfht_node *node,
                struct cds_lfht_iter *unique_ret,
@@ -892,6 +891,7 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
  */
 static
 void _cds_lfht_add(struct cds_lfht *ht,
+               cds_lfht_match_fct match,
                unsigned long size,
                struct cds_lfht_node *node,
                struct cds_lfht_iter *unique_ret,
@@ -944,7 +944,7 @@ void _cds_lfht_add(struct cds_lfht *ht,
                                 * (including observe one node by one node
                                 * by forward iterations)
                                 */
-                               cds_lfht_next_duplicate(ht, &d_iter);
+                               cds_lfht_next_duplicate(ht, match, &d_iter);
                                if (!d_iter.node)
                                        goto insert;
 
@@ -1120,7 +1120,7 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
                           i, j, (1UL << (i - 1)) + j);
                new_node->p.reverse_hash =
                                bit_reverse_ulong((1UL << (i - 1)) + j);
-               _cds_lfht_add(ht, 1UL << (i - 1),
+               _cds_lfht_add(ht, NULL, 1UL << (i - 1),
                                new_node, NULL, 1);
        }
        ht->cds_lfht_rcu_read_unlock();
@@ -1337,10 +1337,7 @@ void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
        }
 }
 
-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,
+struct cds_lfht *_cds_lfht_new(unsigned long init_size,
                        unsigned long min_alloc_size,
                        int flags,
                        void (*cds_lfht_call_rcu)(struct rcu_head *head,
@@ -1368,9 +1365,6 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        ht = calloc(1, sizeof(struct cds_lfht));
        assert(ht);
        ht->flags = flags;
-       ht->hash_fct = hash_fct;
-       ht->compare_fct = compare_fct;
-       ht->hash_seed = hash_seed;
        ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
        ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu;
        ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock;
@@ -1392,14 +1386,13 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        return ht;
 }
 
-void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
-               struct cds_lfht_iter *iter)
+void cds_lfht_lookup(struct cds_lfht *ht, cds_lfht_match_fct match,
+               unsigned long hash, void *key, struct cds_lfht_iter *iter)
 {
        struct cds_lfht_node *node, *next, *dummy_node;
        struct _cds_lfht_node *lookup;
-       unsigned long hash, reverse_hash, size;
+       unsigned long 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);
@@ -1422,7 +1415,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
                if (caa_likely(!is_removed(next))
                    && !is_dummy(next)
                    && node->p.reverse_hash == reverse_hash
-                   && caa_likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+                   && caa_likely(match(node, key))) {
                                break;
                }
                node = clear_flag(next);
@@ -1432,17 +1425,16 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
        iter->next = next;
 }
 
-void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter)
+void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
+               struct cds_lfht_iter *iter)
 {
        struct cds_lfht_node *node, *next;
        unsigned long reverse_hash;
        void *key;
-       size_t key_len;
 
        node = iter->node;
        reverse_hash = node->p.reverse_hash;
        key = node->key;
-       key_len = node->key_len;
        next = iter->next;
        node = clear_flag(next);
 
@@ -1458,7 +1450,7 @@ void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter)
                next = rcu_dereference(node->p.next);
                if (caa_likely(!is_removed(next))
                    && !is_dummy(next)
-                   && caa_likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+                   && caa_likely(match(node->key, key))) {
                                break;
                }
                node = clear_flag(next);
@@ -1503,46 +1495,45 @@ void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
        cds_lfht_next(ht, iter);
 }
 
-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)
 {
-       unsigned long hash, size;
+       unsigned long size;
 
-       hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
        node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
        size = rcu_dereference(ht->t.size);
-       _cds_lfht_add(ht, size, node, NULL, 0);
+       _cds_lfht_add(ht, NULL, size, node, NULL, 0);
        ht_count_add(ht, size, hash);
 }
 
 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+                               cds_lfht_match_fct match,
+                               unsigned long hash,
                                struct cds_lfht_node *node)
 {
-       unsigned long hash, size;
+       unsigned long size;
        struct cds_lfht_iter iter;
 
-       hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
        node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
        size = rcu_dereference(ht->t.size);
-       _cds_lfht_add(ht, size, node, &iter, 0);
+       _cds_lfht_add(ht, match, size, node, &iter, 0);
        if (iter.node == node)
                ht_count_add(ht, size, hash);
        return iter.node;
 }
 
 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
+                               cds_lfht_match_fct match,
+                               unsigned long hash,
                                struct cds_lfht_node *node)
 {
-       unsigned long hash, size;
+       unsigned long size;
        struct cds_lfht_iter iter;
 
-       hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
        node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
        size = rcu_dereference(ht->t.size);
        for (;;) {
-               _cds_lfht_add(ht, size, node, &iter, 0);
+               _cds_lfht_add(ht, match, size, node, &iter, 0);
                if (iter.node == node) {
                        ht_count_add(ht, size, hash);
                        return NULL;
index e28c14afc750c7ffe09ec879b44f05488f76dc44..31113533b25187cbf71c0fd8832671d8addc24d1 100644 (file)
@@ -41,6 +41,8 @@
 #define DEFAULT_MIN_ALLOC_SIZE 1
 #define DEFAULT_RAND_POOL      1000000
 
+#define TEST_HASH_SEED 0x42UL
+
 /* Make this big enough to include the POWER5+ L3 cacheline size of 256B */
 #define CACHE_LINE_SIZE 4096
 
@@ -419,6 +421,24 @@ unsigned long test_compare(void *key1, size_t key1_len,
                return 1;
 }
 
+static
+int test_match(struct cds_lfht_node *node, void *arg)
+{
+       return !test_compare(node->key, node->key_len,
+                       arg, sizeof(unsigned long));
+}
+
+static
+void cds_lfht_test_lookup(struct cds_lfht *ht, void *key, size_t key_len,
+               struct cds_lfht_iter *iter)
+{
+       assert(key_len == sizeof(unsigned long));
+
+       cds_lfht_lookup(ht, test_match,
+                       test_hash(key, key_len, TEST_HASH_SEED),
+                       key, iter);
+}
+
 void *thr_count(void *arg)
 {
        printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
@@ -479,7 +499,7 @@ void *thr_reader(void *_count)
 
        for (;;) {
                rcu_read_lock();
-               cds_lfht_lookup(test_ht,
+               cds_lfht_test_lookup(test_ht,
                        (void *)(((unsigned long) rand_r(&rand_lookup) % lookup_pool_size) + lookup_pool_offset),
                        sizeof(void *), &iter);
                node = cds_lfht_iter_get_test_node(&iter);
@@ -551,12 +571,18 @@ void *thr_writer(void *_count)
                                sizeof(void *));
                        rcu_read_lock();
                        if (add_unique) {
-                               ret_node = cds_lfht_add_unique(test_ht, &node->node);
+                               ret_node = cds_lfht_add_unique(test_ht, test_match,
+                                       test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                                       &node->node);
                        } else {
                                if (add_replace)
-                                       ret_node = cds_lfht_add_replace(test_ht, &node->node);
+                                       ret_node = cds_lfht_add_replace(test_ht, test_match,
+                                                       test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                                                       &node->node);
                                else
-                                       cds_lfht_add(test_ht, &node->node);
+                                       cds_lfht_add(test_ht,
+                                               test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                                               &node->node);
                        }
                        rcu_read_unlock();
                        if (add_unique && ret_node != &node->node) {
@@ -574,7 +600,7 @@ void *thr_writer(void *_count)
                } else {
                        /* May delete */
                        rcu_read_lock();
-                       cds_lfht_lookup(test_ht,
+                       cds_lfht_test_lookup(test_ht,
                                (void *)(((unsigned long) rand_r(&rand_lookup) % write_pool_size) + write_pool_offset),
                                sizeof(void *), &iter);
                        ret = cds_lfht_del(test_ht, &iter);
@@ -642,12 +668,18 @@ static int populate_hash(void)
                        sizeof(void *));
                rcu_read_lock();
                if (add_unique) {
-                       ret_node = cds_lfht_add_unique(test_ht, &node->node);
+                       ret_node = cds_lfht_add_unique(test_ht, test_match,
+                               test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                               &node->node);
                } else {
                        if (add_replace)
-                               ret_node = cds_lfht_add_replace(test_ht, &node->node);
+                               ret_node = cds_lfht_add_replace(test_ht, test_match,
+                                               test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                                               &node->node);
                        else
-                               cds_lfht_add(test_ht, &node->node);
+                               cds_lfht_add(test_ht,
+                                       test_hash(node->node.key, node->node.key_len, TEST_HASH_SEED),
+                                       &node->node);
                }
                rcu_read_unlock();
                if (add_unique && ret_node != &node->node) {
@@ -932,8 +964,7 @@ int main(int argc, char **argv)
         * thread from the point of view of resize.
         */
        rcu_register_thread();
-       test_ht = cds_lfht_new(test_hash, test_compare, 0x42UL,
-                       init_hash_size, min_hash_alloc_size,
+       test_ht = cds_lfht_new(init_hash_size, min_hash_alloc_size,
                        (opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0) |
                        CDS_LFHT_ACCOUNTING, NULL);
        ret = populate_hash();
index f4f3373298492b3dee1e71f35277a310af735dd7..9dcaf02c42ae9dbc2b0dc7d55424390e251bb0d8 100644 (file)
@@ -84,11 +84,13 @@ struct cds_lfht;
 
 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, void *key);
 
 /*
  * cds_lfht_node_init - initialize a hash table node
+ * @node: the node to initialize.
+ * @key: pointer to the key to use.
+ * @key_len: the length of the key, in bytes.
  */
 static inline
 void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
@@ -109,10 +111,7 @@ enum {
 /*
  * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
  */
-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,
+struct cds_lfht *_cds_lfht_new(unsigned long init_size,
                        unsigned long min_alloc_size,
                        int flags,
                        void (*cds_lfht_call_rcu)(struct rcu_head *head,
@@ -128,9 +127,6 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
 
 /*
  * cds_lfht_new - allocate a hash table.
- * @hash_fct: the hashing function.
- * @compare_fct: the key comparison function.
- * @hash_seed: the seed for hash function.
  * @init_size: number of nodes to allocate initially. Must be power of two.
  * @min_alloc_size: the smallest allocation size to use. Must be power of two.
  * @flags: hash table creation flags (can be combined with bitwise or: '|').
@@ -151,16 +147,12 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
  * Threads calling this API need to be registered RCU read-side threads.
  */
 static inline
-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,
+struct cds_lfht *cds_lfht_new(unsigned long init_size,
                        unsigned long min_alloc_size,
                        int flags,
                        pthread_attr_t *attr)
 {
-       return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
-                       init_size, min_alloc_size, flags,
+       return _cds_lfht_new(init_size, min_alloc_size, flags,
                        call_rcu, synchronize_rcu, rcu_read_lock,
                        rcu_read_unlock, rcu_thread_offline,
                        rcu_thread_online, rcu_register_thread,
@@ -187,6 +179,7 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
  * @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.
  */
@@ -198,16 +191,22 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
 
 /*
  * cds_lfht_lookup - lookup a node by key.
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @hash: the key hash.
+ * @iter: Node, if found (output). *iter->node set to NULL if not found.
  *
- * Output in "*iter". *iter->node set to NULL if not found.
  * Call with rcu_read_lock held.
  * Threads calling this API need to be registered RCU read-side threads.
  */
-void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
-               struct cds_lfht_iter *iter);
+void cds_lfht_lookup(struct cds_lfht *ht, cds_lfht_match_fct match,
+               unsigned long hash, void *key, struct cds_lfht_iter *iter);
 
 /*
  * cds_lfht_next_duplicate - get the next item with same key (after a lookup).
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @iter: Node, if found (output). *iter->node set to NULL if not found.
  *
  * Uses an iterator initialized by a lookup.
  * Sets *iter-node to the following node with same key.
@@ -218,10 +217,13 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
  * Call with rcu_read_lock held.
  * Threads calling this API need to be registered RCU read-side threads.
  */
-void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter);
+void cds_lfht_next_duplicate(struct cds_lfht *ht,
+               cds_lfht_match_fct match, 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.
@@ -231,6 +233,8 @@ 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.
@@ -241,15 +245,22 @@ 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.
+ * @match: the key match function.
+ * @node: the node to try adding.
  *
  * Return the node added upon success.
  * Return the unique node already present upon failure. If
@@ -264,10 +275,15 @@ void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
  * add_unique and add_replace (see below).
  */
 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+               cds_lfht_match_fct match,
+               unsigned long hash,
                struct cds_lfht_node *node);
 
 /*
  * cds_lfht_add_replace - replace or add a node within hash table.
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @node: the node to add.
  *
  * Return the node replaced upon success. If no node matching the key
  * was present, return NULL, which also means the operation succeeded.
@@ -288,10 +304,15 @@ struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
  * will never generate duplicated keys.
  */
 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
+               cds_lfht_match_fct match,
+               unsigned long hash,
                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
@@ -319,6 +340,8 @@ int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
 
 /*
  * 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.
@@ -337,6 +360,7 @@ 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.
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