[infinispan-dev] BdbjeCacheStore and JdbmCacheStore getExpiryTime todos
Mircea Markus
mircea.markus at jboss.com
Fri Sep 18 05:57:30 EDT 2009
On Sep 16, 2009, at 12:03 PM, Galder Zamarreno wrote:
> Hi,
>
> I'm looking at the TODOs in the Infinispan code base and I've seen
> BdbjeCacheStore and JdbmCacheStore doing the following:
>
> long expiry = entry.getExpiryTime();
> if (entry.getMaxIdle() > 0) {
> // TODO do we need both?
> expiry = entry.getMaxIdle() + System.currentTimeMillis();
> }
> Long at = new Long(expiry);
> Object key = entry.getKey();
> expiryMap.put(at, key);
>
> They use this expiry time as key in a expiryMap that they purge when
> they need to expire entries from the cache store:
>
> protected void purgeInternal() throws CacheLoaderException {
> try {
> Map<Long, Object> expired =
> expiryMap.tailMap(System.currentTimeMillis(), true);
> for (Map.Entry<Long, Object> entry : expired.entrySet()) {
> expiryMap.remove(entry.getKey());
> cacheMap.remove(entry.getValue());
> }
> } catch (RuntimeException caught) {
> throw convertToCacheLoaderException("error purging expired
> entries", caught);
> }
> }
>
> InternalCacheEntry.getExpiryTime() says it has no meaning for entries
> with max idle but without lifespan. Couldn't this be extended to
> support
> max idle too?
>
> For example: TransientCacheEntry.getExpiryTime() could return
> cachevalue.lastUsed + cachevalue.maxIdle. Obviously, this is not fixed
> and it's really a moving target based on when it's used, but
> wouldn't it
> avoid code like the one above?)
>
> In the case where both max idle and lifespan are used, i.e.
> TransientMortalCacheEntry, getExpiryTime() would return whichever time
> is closer to expiration. So, if lifespan says it should expiry in
> Xms +
> 1000ms but lastUsed + maxIdle says it should expiry in Xms + 2000ms,
> lifespan calculation would return, and viceversa.
+1. This will remove the code duplication between the two cache
loaders as well (better design, keep operation where data is).
I think code wise it's only the
TransientMortalCacheEntry.getExpiryTime that needs to change.
>
> Thoughts?
> --
> Galder Zamarreño
> Sr. Software Engineer
> Infinispan, JBoss Cache
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