/** Erases all elements in the list and re-initializes it. */
public void clear() {
// Remove all references in the list.
LinkedListNode node = getLast();
while (node != null) {
node.remove();
node = getLast();
}
// Re-initialize.
head.next = head.previous = head;
}
/** Clears all entries out of cache where the entries are older than the maximum defined age. */
protected synchronized void deleteExpiredEntries() {
// Check if expiration is turned on.
if (maxLifetime <= 0) {
return;
}
// Remove all old entries. To do this, we remove objects from the end
// of the linked list until they are no longer too old. We get to avoid
// any hash lookups or looking at any more objects than is strictly
// neccessary.
LinkedListNode node = ageList.getLast();
// If there are no entries in the age list, return.
if (node == null) {
return;
}
// Determine the expireTime, which is the moment in time that elements
// should expire from cache. Then, we can do an easy check to see
// if the expire time is greater than the expire time.
long expireTime = System.currentTimeMillis() - maxLifetime;
while (expireTime > node.timestamp) {
if (remove(node.object, true) == null) {
LOGGER.warning(
"Error attempting to remove("
+ node.object.toString()
+ ") - cacheObject not found in cache!");
// remove from the ageList
node.remove();
}
// Get the next node.
node = ageList.getLast();
// If there are no more entries in the age list, return.
if (node == null) {
return;
}
}
}