The mutex part is handled right now using the threads code, every item
allocation has a mutex around it, so this should be safe by calling
inside the item_allocation.
Right now every item does have its own cas id. If you propose the
following scenario:
set foo -> id 0
gets foo -> id 0
delete foo
set foo -> id 0
cas foo -> sent using 0
That would succeed when it should of failed. The second set should of
caused it to be 1.
Chris Goffinet
[EMAIL PROTECTED]
On Nov 11, 2007, at 10:39 PM, Tomash Brechko wrote:
On Sun, Nov 11, 2007 at 14:37:07 -0800, Dustin Sallings wrote:
Can you take a look at this and see if it makes any more sense?
diff --git a/items.c b/items.c
--- a/items.c
+++ b/items.c
@@ -37,6 +38,15 @@ void item_init(void) {
tails[i] = NULL;
sizes[i] = 0;
}
+}
+
+/* Get the next CAS id for a new item. */
+uint64_t get_cas_id() {
+ static uint64_t cas_id;
+ if(cas_id >= MAX_CAS_ID) {
+ cas_id = 0;
+ }
+ return ++cas_id;
}
Seems like you want to have a global CAS counter. This would require
you to have a mutex on it. Wouldn't it be better to have a CAS local
to each item? Becase all we need is an unique (key,CAS) pair, we
don't have to have each CAS to be unique by itself. Besides, this
will decrease the chance of wraparound to effectively zero.
@@ -129,6 +139,7 @@ item *do_item_alloc(char *key, const siz
it->it_flags = 0;
it->nkey = nkey;
it->nbytes = nbytes;
+ it->cas_id = get_cas_id();
Then this would be it->cas_id = 0;, 'gets' will return current value,
and 'cas' will do ++it->cas_id; (no need to have MAX_CAS_ID, C
guarantees no error on wraparound of unsigned types, not to say that
it will never happen).
--
Tomash Brechko
