agentzh
commented
11 years ago Hello!
On Mon, Mar 4, 2013 at 10:02 AM, Thomas12 notifications@github.com wrote:
As you might know: Session management without a locking mechanism can lead to data-corruption as parallel requests will cause race-conditions. Please add this feature:
res=shdict:lock_key(key); res=shdict:unlock_key(key);
You can implement a custom lock by using the "add", "delete" methods and ngx.sleep yourself, as discussed here:
http://groups.google.com/group/openresty-en/browse_thread/thread/4c91de9fc25dd2d7
And that's a common practice in the Memcached community. I may add a transaction API to shared dict as in Redis in the future, but I don't want to expose a locking/unlocking API because it's not a good practice for a key-value store IMHO.
Best regards, -agentzh
As you might know: Session management without a locking mechanism can lead to data-corruption as parallel requests will cause race-conditions. Please add this feature:
res=shdict:lock_key(key); res=shdict:unlock_key(key);
And for performance-reasons a combined command for the most obvious tasks:
data, res=shdict:lock_key_and_get(key); res=shdict:set_and_unlock_key(key, data);
and do an auto-unlock for all keys still being locked for that request when the Lua-script ends.
Maybe one could also allow a security-auto-unlock after 30 seconds. You just put a new int into your shdict node-structure and when it is 0 it is unlocked. When it contains a timestamp > 0 it is locked and when now-timestamp>30 then ignore this previous lock when trying to lock it. Locktime-limit can be set as second parameter in lock_key(key, lock_timeout) and lock_key_and_get(key, lock_timeout).