[ltt-dev] [PATCH 3/7] rculfhash: make cds_lfht_lookup() more generic

[Lai Jiangshan]

We use hash value to determine the range of the object
and use cds_lfht_lookup_fct to lookup them.

Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
---
 rculfhash.c            |    8 ++++----
 tests/test_urcu_hash.c |   25 ++++++++++++++++++++++---
 urcu/rculfhash.h       |    4 +++-
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/rculfhash.c b/rculfhash.c
index d1a1766..29054cd 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1391,14 +1391,14 @@ 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,
+void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
+		cds_lfht_lookup_fct match, void *arg,
 		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);
@@ -1421,7 +1421,7 @@ 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, arg))) {
 				break;
 		}
 		node = clear_flag(next);
diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
index e28c14a..4c45573 100644
--- a/tests/test_urcu_hash.c
+++ b/tests/test_urcu_hash.c
@@ -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 +421,23 @@ 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_hash(key, key_len, TEST_HASH_SEED),
+			test_match, key, iter);
+}
+
 void *thr_count(void *arg)
 {
 	printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
@@ -479,7 +498,7 @@ 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);
@@ -574,7 +593,7 @@ 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);
@@ -932,7 +951,7 @@ 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,
+	test_ht = cds_lfht_new(test_hash, test_compare, TEST_HASH_SEED,
 			init_hash_size, min_hash_alloc_size,
 			(opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0) |
 			CDS_LFHT_ACCOUNTING, NULL);
diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index f4f3373..b56fe56 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -86,6 +86,7 @@ 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_lookup_fct)(struct cds_lfht_node *node, void *arg);
 
 /*
  * cds_lfht_node_init - initialize a hash table node
@@ -203,7 +204,8 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
  * 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,
+void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
+		cds_lfht_lookup_fct match, void *arg,
 		struct cds_lfht_iter *iter);
 
 /*
-- 
1.7.4.4