add max_nr_buckets argument

[ Edit by Mathieu Desnoyers: clarify cds_lfht_new() description. ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rculfhash.c b/rculfhash.c
index 8282f09256e7bbec6384e91cd630692b4e524e2f..4a611a1718451f229d03ea8d7ea5800b18b633dd 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -267,6 +267,7 @@ struct cds_lfht {
        struct rcu_table t;
        unsigned long min_alloc_buckets_order;
        unsigned long min_nr_alloc_buckets;
+       unsigned long max_nr_buckets;
        int flags;
        /*
         * We need to put the work threads offline (QSBR) when taking this
@@ -1365,6 +1366,7 @@ void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size)
 
 struct cds_lfht *_cds_lfht_new(unsigned long init_size,
                        unsigned long min_nr_alloc_buckets,
+                       unsigned long max_nr_buckets,
                        int flags,
                        void (*cds_lfht_call_rcu)(struct rcu_head *head,
                                        void (*func)(struct rcu_head *head)),
@@ -1383,11 +1385,22 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
        /* min_nr_alloc_buckets must be power of two */
        if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1)))
                return NULL;
+
        /* init_size must be power of two */
        if (!init_size || (init_size & (init_size - 1)))
                return NULL;
+
+       if (!max_nr_buckets)
+               max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);
+
+       /* max_nr_buckets must be power of two */
+       if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1)))
+               return NULL;
+
        min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE);
        init_size = max(init_size, MIN_TABLE_SIZE);
+       max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets);
+       init_size = min(init_size, max_nr_buckets);
        ht = calloc(1, sizeof(struct cds_lfht));
        assert(ht);
        ht->flags = flags;
@@ -1407,6 +1420,7 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
        ht->t.resize_target = 1UL << order;
        ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
        ht->min_alloc_buckets_order = get_count_order_ulong(min_nr_alloc_buckets);
+       ht->max_nr_buckets = max_nr_buckets;
        cds_lfht_create_bucket(ht, 1UL << order);
        ht->t.size = 1UL << order;
        return ht;
@@ -1766,6 +1780,7 @@ void resize_target_update_count(struct cds_lfht *ht,
                                unsigned long count)
 {
        count = max(count, MIN_TABLE_SIZE);
+       count = min(count, ht->max_nr_buckets);
        uatomic_set(&ht->t.resize_target, count);
 }
 
@@ -1823,6 +1838,7 @@ void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int grow
 {
        unsigned long target_size = size << growth;
 
+       target_size = min(target_size, ht->max_nr_buckets);
        if (resize_target_grow(ht, target_size) >= target_size)
                return;
 
@@ -1841,6 +1857,7 @@ void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
        if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
                return;
        count = max(count, MIN_TABLE_SIZE);
+       count = min(count, ht->max_nr_buckets);
        if (count == size)
                return;         /* Already the right size, no resize needed */
        if (count > size) {     /* lazy grow */

diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
index 01ae01aa61ded92feb2ce100d54bba3775188124..043a33a9353105eac57e2363693bdfb41c49f12c 100644 (file)
--- a/tests/test_urcu_hash.c
+++ b/tests/test_urcu_hash.c
@@ -967,7 +967,7 @@ int main(int argc, char **argv)
         * thread from the point of view of resize.
         */
        rcu_register_thread();
-       test_ht = cds_lfht_new(init_hash_size, min_hash_alloc_size,
+       test_ht = cds_lfht_new(init_hash_size, min_hash_alloc_size, (1UL << 18),
                        (opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0) |
                        CDS_LFHT_ACCOUNTING, NULL);
        ret = populate_hash();

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index d242ff6485addffd97d05a8bfbba803681656944..6953ad12499b515819b73e56808106fdf55926e1 100644 (file)
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -99,6 +99,7 @@ enum {
  */
 struct cds_lfht *_cds_lfht_new(unsigned long init_size,
                        unsigned long min_nr_alloc_buckets,
+                       unsigned long max_nr_buckets,
                        int flags,
                        void (*cds_lfht_call_rcu)(struct rcu_head *head,
                                void (*func)(struct rcu_head *head)),
@@ -113,8 +114,11 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
 
 /*
  * cds_lfht_new - allocate a hash table.
- * @init_size: number of nodes to allocate initially. Must be power of two.
- * @min_nr_alloc_buckets: the smallest allocation size to use. Must be power of two.
+ * @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.
@@ -138,10 +142,11 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
 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, flags,
+       return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets, flags,
                        call_rcu, synchronize_rcu, rcu_read_lock,
                        rcu_read_unlock, rcu_thread_offline,
                        rcu_thread_online, rcu_register_thread,