Re: [infinispan-dev] BdbjeCacheStore and JdbmCacheStore getExpiryTime todos

On 16 Sep 2009, at 10:03, 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? Well that would be tough since as you say it would be a moving target. And as a moving target, it would require care in how the value is used. E.g., long expiry = e.getExpiryTime(); while (expiry< System.currentTimeMillis()) { // do some stuff } // remove entry Would lead to incorrect behaviour if some other thread updates the entry.

In the case of a cache loader this makes sense since an entry would only be loaded if it isn't in memory (and hence no one else is using it).