private void initWorkQueue() {
BatchWorker<Object> batchWorker =
new BatchWorker<Object>() {
@Override
public void process(Collection<? extends Object> collection) {
// only fetch this once for each process() call
long accessTime = System.currentTimeMillis();
HashSet<Object> keysToProcess = new HashSet<Object>();
for (Object key : collection) {
// check if it was loaded by someone else in the meantime -- does it still qualify for
// refresh ahead?
Element quickTest = underlyingCache.getQuiet(key);
if (quickTest == null
|| checkForRefresh(
quickTest, accessTime, refreshAheadConfig.getTimeToRefreshMillis())) {
final Element ersatz = new Element(key, REFRESH_VALUE);
if (supportCache.putIfAbsent(ersatz) == null) {
// work, work, work
keysToProcess.add(key);
}
}
}
try {
// iterate through the loaders
for (CacheLoader loader : underlyingCache.getRegisteredCacheLoaders()) {
// if we are out of keys, punt
if (keysToProcess.isEmpty()) {
break;
}
// try and load them all
Map<? extends Object, ? extends Object> values = loader.loadAll(keysToProcess);
// subtract the ones that were loaded
keysToProcess.removeAll(values.keySet());
try {
for (Map.Entry<? extends Object, ? extends Object> entry : values.entrySet()) {
Element newElement = new Element(entry.getKey(), entry.getValue());
underlyingCache.put(newElement);
refreshSuccessCount.incrementAndGet();
}
} finally {
// subtract from the support cache
supportCache.removeAll(values.keySet());
}
}
// assume we got here ok, now evict any that don't evict
if (refreshAheadConfig.isEvictOnLoadMiss() && !keysToProcess.isEmpty()) {
underlyingCache.removeAll(keysToProcess);
}
} finally {
// this is utterly paranoid. but still.
supportCache.removeAll(keysToProcess);
}
}
};
this.refreshWorkQueue =
new ThreadedWorkQueue<Object>(
batchWorker,
refreshAheadConfig.getNumberOfThreads(),
new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
return t;
}
},
refreshAheadConfig.getMaximumRefreshBacklogItems(),
refreshAheadConfig.getBatchSize());
}
