In my experience, you wouldn't want the map to return null if the time
has expired. You would want it to return a "refreshed" value. So,
you would want to have the user provide a RefreshProvider (or whatever
you want to call it):
public interface RefreshProvider
{
public Object getValueForKey( Object key );
}
That way, if the value is expired, it could check with the provider to
get a fresh copy of the value.
On 2/7/07, Stephen Colebourne <[EMAIL PROTECTED]> wrote:
This sounds a little too specific for me. I suspect that most people
that want an expiring map will want it to be active not passive.
Stephen
Elifarley wrote:
> I've developed a Map decorator which passively evicts expired entries once
their
> expiry time has been reached.
>
> When putting an item in the map, the decorator calls the 'expiryTime' method,
> passing the key and the value as parameters, and uses the returned value as
the
> expiry time for that entry.
>
> The default implementation of 'expiryTime' just assigns a time 60 seconds in
the
> future for every entry, but subclasses can provide their own policy.
>
> When getting the value for an entry, its expiry time is checked, and if its
> greater than the current time, the value is returned. Otherwise, the entry is
> removed from the decorated map, and null is returned.
> Doing so, there's no need to have a separate, active thread (hence the name
> 'passive') to check expiry times - the check is performed on demand.
>
> I've developed it for my own use, but maybe this could be useful to others
too.
>
> Any thoughts ?
>
> Regards,
> Elifarley
>
>
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