* Lai Jiangshan ([email protected]) wrote:
> Signed-off-by: Lai Jiangshan <[email protected]>
> ---
> rculfhash.c | 47 +++++++++++++++++++++--------------------------
> 1 files changed, 21 insertions(+), 26 deletions(-)
>
> diff --git a/rculfhash.c b/rculfhash.c
> index 49f3637..1c859ed 100644
> --- a/rculfhash.c
> +++ b/rculfhash.c
> @@ -711,6 +711,22 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned
> long v)
> return v;
> }
>
> +static
> +struct _cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
> + unsigned long hash)
> +{
> + unsigned long index, order;
> +
> + assert(size > 0);
> + index = hash & (size - 1);
> + order = get_count_order_ulong(index + 1);
> +
> + dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
> + hash, index, order, index & (!order ? 0 : ((1UL << (order -
> 1)) - 1)));
> +
> + return &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order -
> 1)) - 1))];
> +}
> +
> /*
> * Remove all logically deleted nodes from a bucket up to a certain node key.
> */
> @@ -767,7 +783,6 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long
> size,
> struct cds_lfht_node *dummy, *old_next;
> struct _cds_lfht_node *lookup;
> int flagged = 0;
> - unsigned long hash, index, order;
>
> if (!old_node) /* Return -ENOENT if asked to replace NULL node */
> goto end;
> @@ -812,11 +827,7 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long
> size,
> * lookup for the node, and remove it (along with any other
> * logically removed node) if found.
> */
> - hash = bit_reverse_ulong(old_node->p.reverse_hash);
> - assert(size > 0);
> - index = hash & (size - 1);
> - order = get_count_order_ulong(index + 1);
> - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order
> - 1)) - 1))];
> + lookup = lookup_bucket(ht, size,
> bit_reverse_ulong(old_node->p.reverse_hash));
> dummy = (struct cds_lfht_node *) lookup;
> _cds_lfht_gc_bucket(dummy, new_node);
> end:
> @@ -841,7 +852,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
> struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
> *dummy_node, *return_node;
> struct _cds_lfht_node *lookup;
> - unsigned long hash, index, order;
>
> assert(!is_dummy(node));
> assert(!is_removed(node));
> @@ -850,7 +860,7 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
> node->p.next = flag_dummy(get_end());
> return node; /* Initial first add (head) */
> }
> - hash = bit_reverse_ulong(node->p.reverse_hash);
> + lookup = lookup_bucket(ht, size,
> bit_reverse_ulong(node->p.reverse_hash));
> for (;;) {
> uint32_t chain_len = 0;
>
> @@ -858,9 +868,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
> * iter_prev points to the non-removed node prior to the
> * insert location.
> */
> - index = hash & (size - 1);
> - order = get_count_order_ulong(index + 1);
> - lookup = &ht->t.tbl[order]->nodes[index & ((!order ? 0 : (1UL
> << (order - 1))) - 1)];
There is a reason why the lookup bucket is done in the loop and in the
gc_end path below: it deals with concurrent hash table resizes. So I
agree that merging these code paths into lookup_bucket is good, but I
think you are changing the behavior here.
Or maybe you have something else in mind that guarantees that the change
you do here is correct ?
Thanks,
Mathieu
> iter_prev = (struct cds_lfht_node *) lookup;
> /* We can always skip the dummy node initially */
> iter = rcu_dereference(iter_prev->p.next);
> @@ -936,9 +943,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
> }
> gc_end:
> /* Garbage collect logically removed nodes in the bucket */
> - index = hash & (size - 1);
> - order = get_count_order_ulong(index + 1);
> - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order
> - 1)) - 1))];
> dummy_node = (struct cds_lfht_node *) lookup;
> _cds_lfht_gc_bucket(dummy_node, node);
> end:
> @@ -953,7 +957,6 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
> struct cds_lfht_node *dummy, *next, *old;
> struct _cds_lfht_node *lookup;
> int flagged = 0;
> - unsigned long hash, index, order;
>
> if (!node) /* Return -ENOENT if asked to delete NULL node */
> goto end;
> @@ -984,11 +987,7 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long
> size,
> * the node, and remove it (along with any other logically removed node)
> * if found.
> */
> - hash = bit_reverse_ulong(node->p.reverse_hash);
> - assert(size > 0);
> - index = hash & (size - 1);
> - order = get_count_order_ulong(index + 1);
> - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order
> - 1)) - 1))];
> + lookup = lookup_bucket(ht, size,
> bit_reverse_ulong(node->p.reverse_hash));
> dummy = (struct cds_lfht_node *) lookup;
> _cds_lfht_gc_bucket(dummy, node);
> end:
> @@ -1313,17 +1312,13 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key,
> size_t key_len,
> {
> struct cds_lfht_node *node, *next, *dummy_node;
> struct _cds_lfht_node *lookup;
> - unsigned long hash, reverse_hash, index, order, size;
> + unsigned long hash, 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);
> - index = hash & (size - 1);
> - order = get_count_order_ulong(index + 1);
> - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order
> - 1))) - 1)];
> - dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
> - hash, index, order, index & (!order ? 0 : ((1UL << (order -
> 1)) - 1)));
> + lookup = lookup_bucket(ht, size, hash);
> dummy_node = (struct cds_lfht_node *) lookup;
> /* We can always skip the dummy node initially */
> node = rcu_dereference(dummy_node->p.next);
> --
> 1.7.4.4
>
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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