[ltt-dev] [PATCH 3/9] add cds_lfht_add_at()

[mathieu.desnoyers@efficios.com (Mathieu Desnoyers)]

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> It seems that the testing patches have a strange problem, please wait
> before merge it.

OK, will wait. I'm a bit puzzled as to what this "add_to_at" actually
helps us doing ? What is the use-case for this new API ?

Thanks,

Mathieu

> 
> Thanks,
> Lai
> 
> On 11/14/2011 12:50 PM, Lai Jiangshan wrote:
> > Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> > ---
> >  rculfhash.c      |   24 +++++++++++++++++++++++-
> >  urcu/rculfhash.h |   14 ++++++++++++++
> >  2 files changed, 37 insertions(+), 1 deletions(-)
> > 
> > diff --git a/rculfhash.c b/rculfhash.c
> > index cbfc79e..70f5863 100644
> > --- a/rculfhash.c
> > +++ b/rculfhash.c
> > @@ -1495,12 +1495,34 @@ void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
> >  {
> >  	unsigned long size;
> >  
> > -	node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
> > +	node->reverse_hash = bit_reverse_ulong(hash);
> >  	size = rcu_dereference(ht->t.size);
> >  	_cds_lfht_add(ht, NULL, NULL, size, node, NULL, 0);
> >  	ht_count_add(ht, size, hash);
> >  }
> >  
> > +bool cds_lfht_add_at(struct cds_lfht *ht, struct cds_lfht_iter *iter,
> > +		unsigned long hash, struct cds_lfht_node *node)
> > +{
> > +	struct cds_lfht_node *new_node;
> > +
> > +	if (caa_unlikely(is_removed(iter->next)))
> > +		return false;
> > +
> > +	node->reverse_hash = bit_reverse_ulong(hash);
> > +	node->next = clear_flag(iter->next);
> > +	if (is_bucket(iter->next))
> > +		new_node = flag_bucket(node);
> > +	else
> > +		new_node = node;
> > +	if (uatomic_cmpxchg(&iter->node->next, iter->next,
> > +			new_node) != iter->next)
> > +		return false;
> > +
> > +	ht_count_add(ht, rcu_dereference(ht->t.size), hash);
> > +	return true;
> > +}
> > +
> >  struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
> >  				unsigned long hash,
> >  				cds_lfht_match_fct match,
> > diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
> > index 7d919d0..0f9bf44 100644
> > --- a/urcu/rculfhash.h
> > +++ b/urcu/rculfhash.h
> > @@ -250,6 +250,20 @@ void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
> >  		struct cds_lfht_node *node);
> >  
> >  /*
> > + * cds_lfht_add_at - add a node to the hash table at the specified place.
> > + * @ht: the hash table.
> > + * @iter: the specified place to insert
> > + * @hash: the key hash.
> > + * @node: the node to add.
> > + *
> > + * This function supports adding redundant keys into the table.
> > + * Call with rcu_read_lock held.
> > + * Threads calling this API need to be registered RCU read-side threads.
> > + */
> > +bool cds_lfht_add_at(struct cds_lfht *ht, struct cds_lfht_iter *iter,
> > +		unsigned long hash, struct cds_lfht_node *node);
> > +
> > +/*
> >   * cds_lfht_add_unique - add a node to hash table, if key is not present.
> >   * @ht: the hash table.
> >   * @hash: the node's hash.
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com