[rfc -tip] lib,rb-tree - introduce rb_for_each helper

[rfc -tip] lib,rb-tree - introduce rb_for_each helper

[Cyrill Gorcunov]

perftools already use a number of opencoded
for() iterators over rbtree. The patch introduce
rb_for_each helper for this purpose.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
---

The real conversion for this macro usage should be
done later.

Also I think having rb_for_each_entry for being used
with container_of inbetween could be convinient as
well.

Anyway if we don't need such a helper -- just drop
the patch.

 include/linux/rbtree.h |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6.git/include/linux/rbtree.h
=====================================================================
--- linux-2.6.git.orig/include/linux/rbtree.h
+++ linux-2.6.git/include/linux/rbtree.h
@@ -145,6 +145,9 @@ extern struct rb_node *rb_prev(const str
 extern struct rb_node *rb_first(const struct rb_root *);
 extern struct rb_node *rb_last(const struct rb_root *);
 
+#define rb_for_each(nd, root) \
+	for (nd = rb_first((root)); nd; nd = rb_next(nd))
+
 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
 			    struct rb_root *root);

Re: [rfc -tip] lib,rb-tree - introduce rb_for_each helper

[Frederic Weisbecker]

On Sun, Jul 12, 2009 at 02:00:09AM +0400, Cyrill Gorcunov wrote:
> perftools already use a number of opencoded
> for() iterators over rbtree. The patch introduce
> rb_for_each helper for this purpose.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> ---
> 
> The real conversion for this macro usage should be
> done later.
> 
> Also I think having rb_for_each_entry for being used
> with container_of inbetween could be convinient as
> well.
> 
> Anyway if we don't need such a helper -- just drop
> the patch.
> 
>  include/linux/rbtree.h |    3 +++
>  1 file changed, 3 insertions(+)
> 
> Index: linux-2.6.git/include/linux/rbtree.h
> =====================================================================
> --- linux-2.6.git.orig/include/linux/rbtree.h
> +++ linux-2.6.git/include/linux/rbtree.h
> @@ -145,6 +145,9 @@ extern struct rb_node *rb_prev(const str
>  extern struct rb_node *rb_first(const struct rb_root *);
>  extern struct rb_node *rb_last(const struct rb_root *);
>  
> +#define rb_for_each(nd, root) \
> +	for (nd = rb_first((root)); nd; nd = rb_next(nd))
> +
>  /* Fast replacement of a single node without remove/rebalance/add/rebalance */
>  extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
>  			    struct rb_root *root);


Nice idea!
This pattern is often taken in perfcounter tools.
Also to complete this pattern, an abstract container retrieval
would be also useful as an iterator:

#define rb_for_each_entry(tpos, pos, root, memb) \
	for (pos = rb_first(root); pos && tpos = rb_entry(pos, typeof(*tpos), memb); \
	     pos = rb_next(pos->memb, typeof(*pos), memb))

Or something like that...

Re: [rfc -tip] lib,rb-tree - introduce rb_for_each helper

[Frederic Weisbecker]

On Sun, Jul 12, 2009 at 12:29:30AM +0200, Frederic Weisbecker wrote:
> 	     pos = rb_next(pos->memb, typeof(*pos), memb))

pos = rb_next(pos) would suffice :)

Re: [rfc -tip] lib,rb-tree - introduce rb_for_each helper

[Cyrill Gorcunov]

[Frederic Weisbecker - Sun, Jul 12, 2009 at 12:32:33AM +0200]
| On Sun, Jul 12, 2009 at 12:29:30AM +0200, Frederic Weisbecker wrote:
| > 	     pos = rb_next(pos->memb, typeof(*pos), memb))
| 
| pos = rb_next(pos) would suffice :)
| 

Hi Frederic,

mind to pick the patch up and complete it with
rb_for_each_entry as well? ;)

	-- Cyrill

Re: [rfc -tip] lib,rb-tree - introduce rb_for_each helper

[Peter Zijlstra]

On Sun, 2009-07-12 at 00:29 +0200, Frederic Weisbecker wrote:
> #define rb_for_each_entry(tpos, pos, root, memb) \
>         for (pos = rb_first(root); pos && tpos = rb_entry(pos, typeof(*tpos), memb); \
>              pos = rb_next(pos->memb, typeof(*pos), memb))

if you really want to do this, then at least call it:
for_each_rb_entry().