* 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 should be aligned on 8-bytes boundaries because
+ * the three lower bits are used as flags. It is worth noting that the
+ * information contained within these three bits could be represented on
+ * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and
+ * BUCKET_FLAG. This can be done if we ensure that no iterator nor
+ * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG
+ * is set. Given the minimum size of struct cds_lfht_node is 8 bytes on
+ * 32-bit architectures, we choose to go for simplicity and reserve
+ * three bits.
*
* 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
* of the hash value for cds_lfht APIs.
*/
struct cds_lfht_node {
- struct cds_lfht_node *next; /* ptr | BUCKET_FLAG | REMOVED_FLAG */
+ struct cds_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
unsigned long reverse_hash;
-} __attribute__((aligned(4)));
+} __attribute__((aligned(8)));
/* cds_lfht_iter: Used to track state while traversing a hash chain. */
struct cds_lfht_iter {
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);
+ flags, NULL, &rcu_flavor, attr);
}
/*