Retrieving the age of a given key

[Jeremy Blain]

Randy Wigginton wrote:

> I do it by simply having a prefix for the date.  ie,
> mc.put("DATE"+key, new Date());
> mc.put(key, myObject);
>
Then you're storing 2 objects on each set, and getting 2 objects on each 
get.

If you need them to expire at a specific time, why not use the actual 
timestamp
of when you want them to expire as the expiry time?

(from perl doc)
"If value is less than 60*60*24*30 (30 days), time is assumed to be 
relative from the
present.  If larger, it's considered an absolute Unix time."

Of course the easiest solution might be to add a section to the end of 
your update
process that connects to each server and executes a "flush_all", then 
you don't
need to worry about time at all in your application. (This assumes your 
usage
is low enough that emptying the whole cache at once won't cause things 
to explode)

> Works for me, YMMV.
>
> On Aug 18, 2006, at 12:45 PM, Anthony Volodkin wrote:
>
>> Hi,
>>
>>
>> Is there any way to get the age of a given key when you retrieve it  
>> from memcache?
>>
>>
>> A portion of my app currently uses disk-based caching to store the  
>> HTML generated from dynamic pages.  A major update is "published"  on 
>> the site once an hour and at that point the code knows not to  use 
>> the cached files and overwrites them with new data as requests  come 
>> in.  This is implemented by checking modification times of the  cache 
>> files vs another datetime value.
>>
>> I want to start using memcached for this instead of the disk.
>>
>> To make it work, I would need to know the age of any given key.   
>> Using the more-traditional expiration feature of memcached can lead  
>> to having an inconsistent set of data.  It would also be very  
>> difficult to flush the appropriate keys as these hourly updates are  
>> published.
>>
>>
>> What do you guys think?
>>
>>
>> Thank you,
>>
>> -Anthony
>>