it is not required that ht->t.size >= ht->min_table_size anymore

Original code always ensure ht->t.size >= ht->min_table_size.
This can be improved: ht->min_table_size should be used for allocation,
not for the bucket size in use.

Why does the original code need to always ensure this ?

  Original code don't do special alloc/free when

    ht->t.size < ht->min_table_size

  in init_table()/fini_table(), so we have to force

    ht->t.size >= ht->min_table_size.

Why does new code become flexible ?

  New code use the wrappers, they handle the special cases.

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 46bfa7ae661439f404518439c7e8e132f5506541..807191593c6e7d7671b7ca6f236657771a7d3f32 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -187,7 +187,8 @@
 /*
  * Define the minimum table size.
  */
-#define MIN_TABLE_SIZE                 1
+#define MIN_TABLE_ORDER                        0
+#define MIN_TABLE_SIZE                 (1UL << MIN_TABLE_ORDER)
 
 #if (CAA_BITS_PER_LONG == 32)
 #define MAX_TABLE_ORDER                        32
@@ -1142,7 +1143,7 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
 {
        unsigned long j, size = 1UL << (i - 1);
 
-       assert(i > ht->min_alloc_order);
+       assert(i > MIN_TABLE_ORDER);
        ht->cds_lfht_rcu_read_lock();
        for (j = size + start; j < size + start + len; j++) {
                struct cds_lfht_node *new_node = bucket_at(ht, j);
@@ -1178,7 +1179,7 @@ void init_table(struct cds_lfht *ht,
 
        dbg_printf("init table: first_order %lu last_order %lu\n",
                   first_order, last_order);
-       assert(first_order > ht->min_alloc_order);
+       assert(first_order > MIN_TABLE_ORDER);
        for (i = first_order; i <= last_order; i++) {
                unsigned long len;
 
@@ -1240,7 +1241,7 @@ void remove_table_partition(struct cds_lfht *ht, unsigned long i,
 {
        unsigned long j, size = 1UL << (i - 1);
 
-       assert(i > ht->min_alloc_order);
+       assert(i > MIN_TABLE_ORDER);
        ht->cds_lfht_rcu_read_lock();
        for (j = size + start; j < size + start + len; j++) {
                struct cds_lfht_node *fini_node = bucket_at(ht, j);
@@ -1277,7 +1278,7 @@ void fini_table(struct cds_lfht *ht,
 
        dbg_printf("fini table: first_order %lu last_order %lu\n",
                   first_order, last_order);
-       assert(first_order > ht->min_alloc_order);
+       assert(first_order > MIN_TABLE_ORDER);
        for (i = last_order; i >= first_order; i--) {
                unsigned long len;
 
@@ -1390,7 +1391,7 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
        if (!init_size || (init_size & (init_size - 1)))
                return NULL;
        min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE);
-       init_size = max(init_size, min_alloc_size);
+       init_size = max(init_size, MIN_TABLE_SIZE);
        ht = calloc(1, sizeof(struct cds_lfht));
        assert(ht);
        ht->flags = flags;
@@ -1720,7 +1721,7 @@ void _do_cds_lfht_shrink(struct cds_lfht *ht,
 {
        unsigned long old_order, new_order;
 
-       new_size = max(new_size, ht->min_alloc_size);
+       new_size = max(new_size, MIN_TABLE_SIZE);
        old_order = get_count_order_ulong(old_size);
        new_order = get_count_order_ulong(new_size);
        dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
@@ -1768,7 +1769,7 @@ static
 void resize_target_update_count(struct cds_lfht *ht,
                                unsigned long count)
 {
-       count = max(count, ht->min_alloc_size);
+       count = max(count, MIN_TABLE_SIZE);
        uatomic_set(&ht->t.resize_target, count);
 }
 
@@ -1843,7 +1844,7 @@ void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
 {
        if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
                return;
-       count = max(count, ht->min_alloc_size);
+       count = max(count, MIN_TABLE_SIZE);
        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 fe650f36a083a81d08991bf1a6b18c85baccd098..01ae01aa61ded92feb2ce100d54bba3775188124 100644 (file)
--- a/tests/test_urcu_hash.c
+++ b/tests/test_urcu_hash.c
@@ -896,7 +896,7 @@ int main(int argc, char **argv)
                return -1;
        }
 
-       if (min_hash_alloc_size && min_hash_alloc_size * (min_hash_alloc_size - 1)) {
+       if (min_hash_alloc_size && min_hash_alloc_size & (min_hash_alloc_size - 1)) {
                printf("Error: Min hash alloc size %lu is not a power of 2.\n",
                        min_hash_alloc_size);
                return -1;