/**
* Adds a new Cacheable object to the cache. The key must be unique.
*
* @param key a unique key for the object being put into cache.
* @param object the Cacheable object to put into cache.
*/
public synchronized void add(long key, Cacheable object) {
// Delete an old entry if it exists.
if (object == null) return;
remove(key);
long objectSize = object.getSize();
if (objectSize == -1) objectSize = CacheSizes.cacheSizeOfObject(object);
// If the object is bigger than the entire cache, simply don't add it.
if (objectSize > maxObjectSize) {
return;
}
size += objectSize;
LongCacheObject cacheObject = new LongCacheObject(object, objectSize);
cachedObjectsHash.put(key, cacheObject);
// Make an entry into the cache order list.
LongLinkedListNode lastAccessedNode = lastAccessedList.addFirst(key);
// StoreImp the cache order list entry so that we can get back to it
// during later lookups.
cacheObject.lastAccessedListNode = lastAccessedNode;
// Add the object to the age list
LongLinkedListNode ageNode = ageList.addFirst(key);
// We make an explicit call to currentTimeMillis() so that total accuracy
// of lifetime calculations is better than one second.
ageNode.timestamp = System.currentTimeMillis();
cacheObject.ageListNode = ageNode;
// If cache is too full, remove least used cache entries until it is
// not too full.
if (size >= maxSize) {
cullCache();
}
}
/**
* Removes an object from cache.
*
* @param key the unique key of the object to remove.
*/
public synchronized void remove(long key) {
LongCacheObject cacheObject = (LongCacheObject) cachedObjectsHash.get(key);
// If the object is not in cache, stop trying to remove it.
if (cacheObject == null) {
return;
}
// remove from the hash map
cachedObjectsHash.removeKey(key);
// remove from the cache order list
cacheObject.lastAccessedListNode.remove();
cacheObject.ageListNode.remove();
// remove references to linked list nodes
cacheObject.ageListNode = null;
cacheObject.lastAccessedListNode = null;
// removed the object, so subtract its size from the total.
size -= cacheObject.size;
}
