On 23 September 2011 16:32, Denis Kudriashov <[email protected]> wrote: > Yes, I know. > > I just use generated object id to create unique file to archive object. > I generate id by current date and time "yyyyMMddHHmmssSSS + object hash". > But It is my mistake. > Now I use "yyyyMMddHHmmssSSS + UUID" (I need date parameter too). > And I think id like "yyyyMMddHHmmssSSS + object address" is good too for my > purpose. >
AFAIK, UUID generation algorithm already includes a current time inside. Which means that your addition of date/time actually superfluous. > > 2011/9/23 Mariano Martinez Peck <[email protected]> >> >> >> On Fri, Sep 23, 2011 at 3:22 PM, Denis Kudriashov <[email protected]> >> wrote: >>> >>> I am sure I see It in some block bost. But dont remember >> >> Ok, but GC can move objects arround. If you stick to that value as #hash >> then you dictionaries will be screw...you would need a rehash. But you don't >> know when to trigger it ;) >> >> >>> >>> 2011/9/23 Mariano Martinez Peck <[email protected]> >>>> >>>> >>>> On Fri, Sep 23, 2011 at 3:02 PM, Denis Kudriashov <[email protected]> >>>> wrote: >>>>> >>>>> Thank you for all your responses. I will use UUID. >>>>> >>>>> Another assumption: >>>>> I know there is a trick to get object memory address. >>>> >>>> which one? >>>> >>>>> >>>>> Can it be used for object identity? (inside memory of objects) >>>>> >>>>> >>>>> >>>>> 2011/9/23 Marcus Denker <[email protected]> >>>>>> >>>>>> On Sep 23, 2011, at 1:08 PM, Denis Kudriashov wrote: >>>>>> >>>>>> > Hello, >>>>>> > >>>>>> > I use hash message to generate unique object id. (unique between >>>>>> > current memory objects). >>>>>> > And I catch situation when two objects has same hash value. Objects >>>>>> > has been created in loop almost at same time. >>>>>> > >>>>>> > So my question - is it really possible? >>>>>> >>>>>> Yes, easily, as there are only 12 bits for the hash, there are only >>>>>> 4096 different hash values. >>>>>> >>>>>> This means that a hash is *not* at all a UUID, and all hashing data >>>>>> structures need to be optimized >>>>>> for the case of hash collision, as it will happen a lot. >>>>>> >>>>>> Marcus >>>>>> >>>>>> >>>>>> -- >>>>>> Marcus Denker -- http://marcusdenker.de >>>>>> >>>>>> >>>>> >>>> >>>> >>>> >>>> -- >>>> Mariano >>>> http://marianopeck.wordpress.com >>>> >>> >> >> >> >> -- >> Mariano >> http://marianopeck.wordpress.com >> > > -- Best regards, Igor Stasenko.
