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Re: [dm-devel] [PATCH v3 01/17] hashtable: introduce a small and naive hashtable



On 09/06/2012 02:53 PM, Sasha Levin wrote:

> So I think that for the hash iterator it might actually be simpler.
> 
> My solution to making 'break' work in the iterator is:
> 
> 	for (bkt = 0, node = NULL; bkt < HASH_SIZE(name) && node == NULL; bkt++)
> 		hlist_for_each_entry(obj, node, &name[bkt], member)
> 
> We initialize our node loop cursor with NULL in the external loop, and the
> external loop will have a new condition to loop while that cursor is NULL.
> 
> My logic is that we can only 'break' when we are iterating over an object in the
> internal loop. If we're iterating over an object in that loop then 'node != NULL'.
> 
> This way, if we broke from within the internal loop, the external loop will see
> node as not NULL, and so it will stop looping itself. On the other hand, if the
> internal loop has actually ended, then node will be NULL, and the outer loop
> will keep running.
> 
> Is there anything I've missed?

Looks right to me, from a cursory look at hlist_for_each_entry.  That's exactly
what I meant with this most often being trivial when the inner loop's iterator
is a pointer that goes NULL at the end.

-- 
Pedro Alves


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