On Fri, 2007-08-24 at 12:26 -0400, Mathieu Desnoyers wrote:
> * Rusty Russell ([email protected]) wrote:
> > On Mon, 2007-08-20 at 16:27 -0400, Mathieu Desnoyers wrote:
> > > +{
> > > + struct hlist_head *head;
> > > + struct hlist_node *node;
> > > + struct marker_entry *e;
> > > + size_t len = strlen(name) + 1;
> > > + u32 hash = jhash(name, len-1, 0);
> > > +
> > > + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
> > > + hlist_for_each_entry(e, node, head, hlist) {
> > > + if (!strcmp(name, e->name))
> > > + return e;
> > > + }
> > > + return NULL;
> > > +}
> >
> > OK, don't understand the strlen, len, len-1 dance here?
> >
>
> Let's say we have abc\0 for marker name as name input.
>
> len = 3 + 1 = 4 (including \0)
> hash is done only on the 3 first chars, excluding the \0 (therefore the
> len-1 there)
>
> Actually, it's like this only for a matter of consistency between
> add_marker and remove_marker, which are quite similar, but add_marker
> needs name_len to include the \0 value. It would be odd to change the
> logic between the two functions to one including the \0 and the other
> excluding it.
Sure, but that doesn't really explain why the code does:
size_t len = strlen(name) + 1;
u32 hash = jhash(name, len-1, 0);
Rather than:
u32 hash = jhash(name, strlen(name), 0);
> Thanks for the review,
That's fine, just some light reading...
Cheers,
Rusty.
>
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