Re: Receiving the all the entries that belongs to a group

You're using the wrong tool to solve your problem. You really should be 
using a database for this, it's exactly the type of problem they're 
designed to handle after all!


Romulus Pasca wrote:
> I have in my application a huge cache which cannot be keep it in
> memory(arround 200MB). So I intended to use a cache with a small
> memory size, and unlimited disk size. Also my entries should never
> expire(are read-only persistent objects). I wanted to keep different
> type of entries(I have around 25-50 types of objects that should be
> cached) in different groups. The keys for entry are a specific prefix
> for each group appended to the hash code of the object (which is
> guaranted to be unique). For some types of entries, for which I load
> all the required data at startup(other entries can be added also
> during the application life time, but these entries are never
> deleted) I have a business requirement, which asks me for all the
> entries of that type. So it looks like I need to get all entries for
> a group(both from memory and disk)- a statical snapshot with the
> members of the group at a specific time. 
> 
> Assuming that it's ok for me to get a statical snapshot of a group, I
> added to the Cache class the following methods:
> 
> public Object[] getGroupFromCache(String groupName, Class entryType) {
>         Set groupEntries = cacheMap.getGroup(groupName);
>         ArrayList result = new ArrayList();
>         if (groupEntries != null) {            
>             Iterator itr = groupEntries.iterator();            
>             while (itr.hasNext()) {
>                 try {
>     result.add(getFromCache((String) itr.next()));                    
>                 } catch (NeedsRefreshException ne) {
>                     //just ignore this entry
>                 }
>             }
>         }
> return result.toArray((Object[])
> java.lang.reflect.Array.newInstance(entryType, result.size()));
>     }
> 
>     public Object[] getGroupFromCache(String groupName) {
>         return getGroupFromCache(groupName, Object.class);
>     }
> Is in your opinion, Chris this code ok? 
> 
> Regarding the performance of the OSCache(because I follow the
> performence discussion about oscache form this mailing list), I have
> big performance problems with my caching model. As I told you I need
> a huge disk-based cache for my application. At my first test with
> OSCache, I was tring to store each item of a big search in the
> cache(there was thousands of items, with a total size of 35MB).
> Without OSCache, the time for this serach was just around a minute.
> When I was trying to store these entries with OSCache, the time jump
> to more then 2 hours.  So it looks that the default persistent
> listener is not suitable for such kind of scenarios...
> 
> Best Regards and Merrie Christmas!
> Romulus



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